bluuebunny/crossref_metadata_2025 huggingface dataset:
Salt‐dependent conformational diversity of alternating poly (Glu‐Leu)
Authors: BERTRAND MARYLÈNE , SY DENISE , BRACK ANDRE
Published: August 2010

Alternating poly(Glu‐Leu) was synthesized by the condensation of the corresponding dipeptide p‐nitrophenyl ester at high concentration. It exhibits a random coil structure in pure water at neutral pH. Addition of monovalent cations, such as NH+4 to a final 0.1 M solution, induces a transition to a water soluble β‐structure. The salt effect is quite selective since no transition was observed with Li+, Na+ or Cs+ ions. Addition of 0.5 equiv. of calcium, cobalt or manganese chlorides per glutamyl residue induces similar coil to β‐sheet transitions. No polymer precipitation was observed at these very low salt concentrations. Addition of 0.5 equiv. of Cu2+ or 0.15 equiv. of Fe3+ induces a coil to α‐helix transition. Molecular modeling has been used to understand tentatively the main factors controlling the different conformations observed with the various metal ions. © Munksgaard 1997.
Role of tryptophan‐14 in the interaction of dynorphin A(1‐17) with micelles
Authors: TESSMER MICHAEL R. , KALLICK DEBORAH A.
Published: August 2010

Fluorescence spectroscopy has been used to examine the interaction between the opioid peptide dynorphin A(1‐17) (dynorphin) and dodecylphosphocholine (DPC) micelles. Fluorescence emission spectra as a function of added lipid indicate insertion of the Trp14side chain into the hydrophobic portion of the micelle, supporting NMR results from this laboratory. A model of interaction with micelles consistent with the fluorescence results and earlier NMR results is proposed. The critical micelle concentration in the presence of peptide was also determined, and is discussed in the context of relevance to both NMR spectroscopy and peptide‐lipid interactions. © Munksgaard 1997.
Peptide synthesis on SepharoseTM beads
Authors: TEGGE WERNER , FRANK RONALD
Published: August 2010

NHS‐activated Pharmacia HiTrap SepharoseTM was modified with 1,3‐diaminopropane to give an amino‐functionalized support suitable for solid‐phase peptide synthesis. The amide linker p‐[(R,S)‐α‐[1‐(9H‐fluoren‐9‐yl)‐methoxyformamido]‐2,4‐dimethoxybenzyl]phenoxyacetic acid was incorporated and the acyl carrier protein sequence 65‐74 was synthesized manually on this support by the Fmoc procedure under controlled conditions with monitoring of the coupling reactions. The performance of the support in automated multiple synthesis in open reactors, with an Abimed AMS 422 according to standard protocols, was evaluated by the synthesis of the acyl carrier protein sequence 65‐74 and two other 15‐mer and 18‐mer peptides. The quality of the resulting crude peptides was determined by HPLC and MALDI‐MS, and compared with the same sequences synthesized in parallel on the commercial peptide synthesis resin TentaGel S RAM. The modified HiTrap material was found to be particularly suited for Fmoc solid‐phase peptide synthesis and should be advantageous for the utilization of immobilized peptides and peptide libraries in biological assays. © Munksgaard 1997.
Insect neuropetide proctolin and its analogues. An overview of the present literature
Authors: KONOPINSKA DANUTA
Published: August 2010

In the present paper, the literature describing synthetic, biological and conformational studies on the insect neuropeptide proctolin (H‐Arg‐Tyr‐Leu‐Pro‐Thr‐OH) and its analogues is summarized. The paper covers proctolin and its 80 analogues modified in positions 1‐5, a cycloanalogue and analogues with a truncated or elongated peptide chain. These peptides were bioassayed by different methods, e.g. studies of myotropic activities in several insect speciesin vitroand behaviour in ratsin vivo. Based on these data structure‐activity relationships are discussed. © Munksgaard 1997.
C5aR ligand peptide 3D QSAR study performed with an applied linear conformation
Authors: ANDERSON CY , KELLOGG GLEN EUGENE , FREER RICHARD J.
Published: August 2010

A 3D quantitative structure‐activity relationship study (QSAR) of binding and activation of the human C5a receptor by peptide analogs of the C‐terminal binding domain of C5a anaphylatoxin is reported. Using published C5a analog affinity and activity data, this paper seeks to elucidate the pharmacophore for the high affinity C‐terminal binding domain of the C5a peptide with the molecular modeling technique of comparative molecular field analysis (CoMFA). In order to model peptides for which there was incomplete conformational data, an arbitrary linear conformation was imposed upon the highly flexible C5a analogs. The resulting models yield a crossvalidated q2 of 0.889 and 0.787, for receptor‐ligand affinity and EC50 calcium release activity, respectively, suggesting these models have good predictive ability for other test peptides.
Efficient peptide ladder sequencing by MALDI‐TOF mass spectrometry using allyl isothiocyanate
Authors: GU QU‐MING , PRESTWICH GLENN D.
Published: August 2010

A new modification of the peptide ladder sequencing technique is described in which allyl isothiocyanate (AITC) replaces trifluoroethyl isothiocyanate as the volatile amine‐modification reagent. AITC is commercially available, readily purified, stable up to 80 °C and reacts cleanly and rapidly with all amino groups of polypeptides. Several model peptides and two side chain‐modified peptides were sequentially degraded using AITC and the cleavage reagent heptafluorobutyric acid (HFBA) up to seven amino acids from the TV‐terminus. Matrix‐assisted laser‐desorption and ionization coupled with time‐of‐flight (MALDITOF) mass spectroscopy of the peptide mixture provided a clear ladder‐like mass profile with consecutive molecular ions corresponding to each shortened peptide at picomole range. The results indicate the general utility of this analytical protocol by the use of AITC as the amine‐coupling reagent.
NMR structure of neuromedin C, a neurotransmitter with an amino terminal CuII‐, NiII‐binding (ATCUN) motif
Authors: Gasmi Geneviève , SINGER ALEX , FORMAN‐KAY JULIE , SARKAR BIBUDHENDRA
Published: August 2010

The structure of neuromedin C, a 10‐residue bombesin‐like neuropeptide with the sequence Gly‐Asn‐His‐Trp‐Ala‐Val‐Gly‐His‐Leu‐Met‐NH2, has been investigated. Like human serum albumin, neuromedin C contains the amino‐terminal CuII‐, NiII‐binding (ATCUN) motif which has high affinity for CuII and NiII. The solution structure of the NiII‐peptide complex has been calculated based on 2D ROESY data obtained at 25°C, using a hybrid distance geometry‐simulated annealing approach. Comparison of H, 13C and 15N chemical shifts and ROESY data in the presence and absence of NiII demonstrates that the metal binds at the N‐terminus of the peptide, leading to a conformational change. The metal complex adopts a conformation comprising two connected turns including residues Gly to 3His and 5Ala to 8His. The first turn corresponds to the NiII coordination ligands in a square planar conformation, and the second reflects the interaction between 4Trp and 8His. The results may have important physiological implications in the phenomenon of neurotransmission. © Munksgaard 1997.
Synthesis, radiolabeling and biological activity of peptide oostatic hormone and its analogues
Authors: HLÁVAČEK JAN , BENNETTOVÁ BLANKA , BARTH TOMISLAV , TYKVA RICHARD
Published: August 2010

A series of Pro peptides containing the sequence of the oostatic hormone3dand its shorter analogues3a‐3cdiffering in a number of the C‐terminal Pro residues was prepared for a study of its effect on oogenesis inSarcophaga bullata Parker(Diptera). Peptides3a‐3dwere synthesized in solution by the fragment condensation of Boc‐Tyr‐Asp(OtBu)‐Pro‐Ala‐Pro‐OH(2f)with Pro oligopeptides H‐(Pro)2‐5‐OtBu. The ammo‐terminal protected pentapeptide acid2fwas prepared by a stepwise procedure from TFA‐H‐Ala‐Pro‐OMe using Boc‐Pro‐OH, Z‐Asp(OtBu)‐OSu and Boc‐Tyr‐OSu. The H(Z)‐(Pro)2‐5‐OtBu oligopeptides1a‐1hwere synthesized from Z‐Pro‐OH and H‐Pro‐OtBu by a combination of stepwise procedure and fragment condensation. The125I‐labeled molecules of the octapeptide3band decapeptide3dwere used for radiotracer distribution studies. Evidence of content of the labeled peptide material in various parts of the insect body (ovaries, head, intestine) is presented. The time distribution of the labeled material in the insect organs was correlated with results of histological analysis of ovaries treated by nonlabeled peptides. The peptides assayed affected processes of egg development in 20–60% of ovarioles. The decapeptide3dcaused changes consisting in some resorbed egg chambers and normal appearance of vitellogenic eggs, whereas the octapeptide3bcaused abnormal yolk deposition and formation of big eggs with irregular yolk granules, proliferation of follicular epithelium in some egg chambers and about the same amount of resorbed egg chambers as decapeptide. These structural differences are complementary to the different values of organ radioactivities. © Munkagaard 1997.
Synthesis, biological activity and isomerism of guanylate cyclase C‐activating peptides guanylin and uroguanylin
Authors: KLODT JOACHIM , KUHN MICHAELA , MARX UTE C. , MARTIN SILKE , RÖUSCH PAUL , FORSSMANN WOLF‐GEORG , ADERMANN KNUT
Published: August 2010

Recently, the peptides guanylin and uroguanylin were identified as endogenous ligands of the membrane‐bound guanylate cyclase C (GC‐C) that is mainly expressed in the intestinal epithelium. In the present study, bioactive guanylin and uroguanylin have been prepared by solid‐phase methodology using Fmoc/HBTU chemistry. The two disulfide bonds with relative 1/3 and 2/4 connectivity have been introduced selectively by air oxidation of thiol groups and iodine treatment of Cys(Acm) residues. Using this strategy, several sequential derivatives were prepared. Temperature‐dependent HPLC characterization of the bioactive products revealed that guanylin‐related peptides exist as a mixture of two compounds. The isoforms are interconverted within approximately 90 min, which prevents their separate characterization. This effect was not detected for uroguanylin‐like peptides. Synthetic peptides were tested for their potential to activate GC‐C in cultured human colon carcinoma cells (T84), known to express high levels of GC‐C. The results obtained show that both disulfide bonds are necessary for GC‐C activation. The presence of the amino‐terminally neighboring residues of Cys104 for guanylin and Cys100 for uroguanylin has been found to be essential for GC‐C stimulation. Unexpectedly, a hybrid peptide obtained from substitution of the central tripeptide AYA of guanylin by the tripeptide VNV of uroguanylin was not bioactive. © Munksgaard 1997.
New mild acid‐labile protecting groups for the guanidino function of Nα‐fluorenylmethoxycarbonyl‐l‐arginine in solid‐phase peptide synthesis: 10, 11‐dihydro‐5H‐dibenzo[a, d]. cyclohepten‐5‐yl, 2‐methoxy‐10, 11‐dihydoro‐5H‐dibenzo[a, d]. cyclohepten‐5‐yl and 5H‐dibenzo[a, d]. cyclohepten‐5‐yl groups
Authors: NODA MASAKI , KIFFE MICHAEL
Published: August 2010

10, 11‐Dihydro‐5H‐dibenzo[a, d]. cyclohepten‐5‐yl [5‐dibenzosuberyl]. and 5H‐dibenzo[a, d]. ‐cyclohepten‐5‐yl [5‐dibenzosuberenyl]. groups have been found to be useful protecting groups for the guanidino function of arginine in solid‐phase peptide synthesis on Fmoc chemistry. The arginine derivatives (4a, b, c) derivatized with these groups were easily deprotected with mild acid (less than 30 min with 25% trifluoroacetic acid). Tryptophan‐containing peptide sequences, two hexapeptides (6) and (8), were synthesized in good yield by mild acid treatment (50% trifluoroacetic acid in 1 h) of the peptide resins (5a, c‐f and 7a, c, d) assembled via 4a, b, c using benzotriazol‐1 ‐yl‐oxy‐tris‐(pyrrolidino)‐phosphonium hexafluorophosphate‐1‐hydroxybenzotriazole mediated coupling.
Common and differential recognition of structural features in synthetic peptides by the catalytic domain and the Src‐Homology 2 (SH2) domain of pp60c‐src
Authors: JOHNSON TIMOTHY M. , PERICH JOHN W. , BJORGE JEFFREY D. , FUJITA DONALD J. , CHENG HEUNG‐CHIN
Published: August 2010

The relative efficiencies of the catalytic domain of the src‐family kinase pp60c‐src in phosphorylating four peptide substrates including (i) src‐optimal peptide (AEEEIYGEFEAKKKK), (ii) “‐YEEI‐peptide” (KKTHQEEEEPQYEEIPIYL), (iii) cdc2(6–20) (KVEKIGEGTYGVVYK), (iv) src‐autophosphorylation site peptide (ADFGLARLIEDNEYTARG) and the relative efficiencies of its SH2 domain in binding the phosphorylated forms of these peptide substrates were compared. The results show that the src‐optimal peptide, “‐YEEI‐peptide, ” cdc2(6–20) peptide were phosphorylated by the catalytic domain with high efficiency and that the phosphorylated form of all three peptides could bind the SH2 domain of the kinase, confirming the hypothesis proposed by Songyang and co‐workers that the catalytic domain of pp60c‐src phosphorylates sites which are recognized by its own SH2 domain (Songyang et al. (1995) Nature 373, 536–539). The four peptides were phosphorylated by the kinase with relative efficiencies in the order of Src‐optimal peptide > “‐YEEI‐peptide” > cdc2(6–20) ≫ src‐autophosphorylation site peptide. However, the Tyr(P)‐Src‐optimal peptide and [pY]. 15cdc2(6–20) bound to the SH2 domain of the kinase with an affinity at least an order of magnitude lower than that of the tight‐binding peptide, “‐pYEEI‐peptide.” Thus, our study suggests that the catalytic and SH2 domains of pp60c‐src recognize overlapping but not identical determinants in the local structure around the tyrosine phosphorylation site of the substrate peptides.
Conformational analysis of potent sweet taste ligands by nuclear magnetic resonance, computer simulations and X‐ray diffraction studies
Authors: MATTERN RALPH‐HEIKO , AMINO YUSUkE , BENEDETTI ETTORE , GOODMAN MURRAY
Published: August 2010

Four potent sweet‐tasting molecules, N‐(3, 3‐dimethylbutyl)‐l‐aspartyl‐l‐phenylalanine methylester 1 (7000 times more potent than sucrose), N‐(3, 3‐dimethylbutyl)‐l‐aspartyl‐d‐valine (S)‐α‐ethylbenzylamide 2 (3000 time more potent than sucrose), l‐aspartyl‐d‐valine (R)‐α‐methoxymethylbenzylamide 3 (1350 times more potent than sucrose and l‐aspartyl‐(1R, 2S, 4S)‐1‐methyl‐2‐hydroxy‐4‐phenylhexylamide 4 (2500 times more potent than sucrose) were studied by H NMR and computer simulations. These flexible molecules adopt multiple conformations in solution. The “L‐shaped” structure, which we believe to be responsible for sweet taste is accessible to all four compounds in solution. Extended conformations with the AH and B‐containing moieties in the +y‐axis and the hydrophobic group X pointing in the y‐axis have also been observed for all four sweeteners. For compounds 1 and 3, the solid‐state conformations were determined by X‐ray diffraction studies. These results demonstrate that compounds 1 and 3 adopt an “L‐shaped” structure even in the crystalline state. The extraordinary potency of the N‐alkylated compound 1 compared with the unsubstituted Asp‐Phe‐OMe may be explained by the effect of a second hydrophobic binding domain in addition to interactions arising from the “L‐shaped” structure.
Crystal and molecular structure of l‐histidyl‐l‐serine trihydrate: occurrence of Cα‐H…O=C hydrogen bond motif similar to the motif in collagen triple helix and β‐sheets
Authors: PADIYAR G. SREEKANTA
Published: August 2010

l‐Histidyl‐l‐serine (HSN) trihydrate, C9H14N4O4H2O crystallizes in the orthorhombic space group P212121with a= 4.865(4), b= 15.604(4), c= 18.918(5) and Z= 4. The crystal structure was solved by direct methods and refined to R1 = 0.070 by a full‐matrix least‐squares method. The peptide exists in a zwitterionic form, with the N‐terminus in a protonated form and the C‐terminus in an ionized form. The imidazole ring of histidine in its neutral Hise tautomeric state has conformational angles X11 of‐53.5(7)° and X211 of‐55.4(8)° and the serine hydroxyl group has X12 of 68.2(7)°. The conformational angles deviate significantly from those of the dipeptide complexed with glycyl‐l‐glutamic acid in which the histidine is protonated. A noteworthy feature of the crystal packing is the occurrence of a Cα‐H O=C hydrogen bond motif similar to that observed in collagen triple helix and β‐sheets.
The design, synthesis and activity of pentapeptide pp60c‐src inhibitors containing L‐phosphotyrosine mimics
Authors: LAI JACK H. , MARSILJE THOMAS H. , CHOI SUN , NAIR SHRIKUMAR A. , HANGAUER DAVID G.
Published: August 2010

Efficient syntheses of 4‐(R,S‐hydroxyphosphonomethyl)‐l‐phenylalanine and 4‐carboxy‐l‐phenylalanine within the context of the pentapeptide Ac‐Ile‐X‐Gly‐Glu‐Phe‐NH2 (wherein X = the unnatural amino acid) illustrate the use of a divergent synthetic strategy from an advanced common peptide intermediate to more readily access peptide‐based tyrosine kinase inhibitors. The key intermediate, Ac‐Ile‐Phe(4‐formyl)‐Gly‐Glu(O‐tBu)‐Phe‐NH2, was synthesized by a facile palladium‐catalyzed carbonylation of Ac‐Ile‐Phe(4‐iodo)‐Gly‐Glu(O‐tBu)‐Phe‐NH2. Oxidation of Ac‐Ile‐Phe(4‐formyl)‐Gly‐Glu(O‐tBu)‐Phe‐NH2 with tetrabutylammonium permanganate or addition of di‐t‐butylphosphite, both followed by trifluoroacetic acid deprotection, gave the target pentapeptide inhibitors wherein X = 4‐carboxy‐l‐phenylalanine or 4‐(R,S‐hydroxyphosphonomethyl)‐l‐phenylalanine, respectively. These two peptides gave somewhat more potent inhibition of the tyrosine kinase pp60c‐src than the corresponding pentapeptide wherein X =l‐phenylalanine, demonstrating that appended functionalities at the 4‐position are accepted and can enhance binding through added interactions within the catalytic region of the active site.
Analysis of synthetic peptides by capillary zone electrophoresis in organic/aqueous buffers
Authors: MILLER CHARLEEN , RIVIER JEAN
Published: August 2010

Whereas synthetic peptides have been routinely analyzed for purity by reverse phase high performance liquid chromatography (RPHPLC) for a number of years, it is only in the last decade that the use of capillary zone electrophoresis (CZE) in aqueous buffers has been taken advantage of as an orthogonal method for the detection of impurities. However, we have found that hydrophobic amino acids and peptides often migrate as very broad, tailing absorbances or even precipitate in the aqueous buffers during CZE analysis. As a result, alternative buffer systems containing organic modifiers were sought. Varying concentrations of acetonitrile, methanol and isopropanol in sodium phosphate and triethylammonium phosphate buffers were used to study their effects on the electrophoretic migration of several synthetic peptides [gonadotropin releasing hormone (GnRH), corticotropin releasing factor (CRF) and analogs] and an enantiomeric synthetic amino acid. The organic/aqueous buffers used to obtain the best conditions for separation of porcine gonadotropin‐releasing hormone (GnRH) and chicken II GnRH were then used to optimize a separation of nine native forms of GnRH decapeptides. Interestingly, several of these GnRHs have identical formal charges and yet could be separated. This suggests a mixed mechanism of separation that discriminates not only on the basis of peptide charge and structure but also of adsorptive properties (Van der Waals forces, dipole‐dipole interactions and hydrogen bonding) of the capillaries.
Peptide aldehyde inhibitors of the kallikreins: an investigation of subsite interactions with tripeptides containing structural variations at the amino terminus
Authors: Garrett G.S. , Correa P.E. , McPhail S.J. , Tornheim K. , Burton J.A. , Eickhoff D.J. , Engerholm G.G. , McIver J.M.
Published: August 2010

Abstract: A series of tripeptide aldehyde derivatives containing variations at the P3 subsite and the amino terminus has been prepared and evaluated for trypsin‐like serine protease inhibition. These compounds exhibit strong in vitro inhibition of human plasma kallikrein (HPK), porcine pancreatic kallikrein (PPK) and human plasmin (HP). As suspected from an examination of a related crystal structure, the presence of a hydrophobic residue (adamantyl) at the amino terminus dramatically improves the binding to PPK. The adamantyl group, however, represents a peak in binding; larger residues cause the binding to be reduced, and thus are less well accommodated in this subsite. Although both HP and HPK also can accept large molecular volume at the amino terminus, they do not exhibit the same preference for large residues at this subsite that is demonstrated by PPK. Selectivity differences also are observed with P3 subsite substitution; with PPK preferring a bulky, but compact side‐chain (t‐butyl) and HP and HPK preferring a more extended (e.g. benzyl) group.
Molecular recognition properties of the C‐terminal Sh3 domain of the Cbl associated protein, Cap
Authors: Kurakin A. , Hoffman N.G. , Kay B.K.
Published: August 2010

Abstract: A phage‐displayed combinatorial peptide library was used to define the specificity of one of the three Src homology 3 (SH3) domains in a novel cytoskeletal protein, named CAP, for Cbl Associated Protein. The C‐terminal SH3 domain was used to affinity select peptides with the consensus, PXPPXRXSSL, from a library of X6PXXPX6 peptides. Peptide sequences resembling this consensus were identified in two signal transduction proteins, c‐Cbl and son‐on‐sevenless (Sos), previously shown to interact with the C‐terminal SH3 domain of CAP. Genetic fusion of 16 and 14 amino acid segments of c‐Cbl and Sos, respectively, to bacterial alkaline phosphatase confirmed that these segments were potential ligand sites for the C‐terminal SH3 domain of CAP. Alanine‐scanning mutagenesis of the c‐Cbl peptide ligand confirmed that most of the residues, which were conserved among the peptide ligands selected from the combinatorial peptide library, contributed to binding to the C‐terminal SH3 domain of CAP.
Investigations into the cross‐reactivity of rabbit antibodies raised against nonhomologous pairs of synthetic peptides derived from HIV‐1 gp120 proteins
Authors: Krsmanovic V. , Biquard J.‐M. , Sikorska‐Walker M. , Cosic I. , Desgranges C. , Trabaud M.‐A. , Whitfield J.F. , Durkin J.P , Achour A. , Hearn M.T.W.
Published: August 2010

Abstract: The immunological cross‐reactivity of several peptides with specific pattern‐property characteristics related to the epitopes of human immunodeficiency virus type 1 (HIV‐1) gp160/ 120 envelope proteins has been investigated. Proteins with similar primary structures can be expected to show functional or topographic similarities, such as specific epitopes which may cross‐react with antibodies derived from the immunisation of animals with other members of the same protein family. These structure‐function characteristics may be revealed as periodicities derived from presentations based on the discrete Fourier transformation of the distributions of various physico‐chemical amino acid descriptors, constituting the polypeptide backbone and amino acid side‐chains of the protein molecule. Such approaches, for example, have permitted prediction of periodicities corresponding to secondary structural motifs, including amphipathic α‐helices and β‐sheets, within protein sequences, and have helped to clarify potential binding sites for ligands, substrates or cofactors with interacting macromolecules. Based on this approach, characteristic periodicities have been identified which represent common Fourier transform spectral properties of the envelope (ENV) gpl60/120 glycoproteins from a range of HIV‐1 isolates. In addition, similar periodicities have been detected as components of the discrete Fourier transform representation of the corresponding amino acid descriptors of the CD4 binding domain of gpl20. Accordingly, we have synthesised several peptides having periodic characteristics in their discrete Fourier transform representations similar to these HIV‐1 proteins. These nonhomologous synthetic peptides induced cross‐reactive antibodies in New Zealand White rabbits. Polyclonal antibodies raised to one of these peptides reacted with HIV‐1 ENV gpl20‐related proteins, as determined by enzyme‐linked immunosorbent assay and Western blotting techniques. These findings provide further evidence for a role of immunological cross‐reactivity and molecular biomimicry in the development of peptide‐based vaccines directed against viral or bacterial pathogens.
NMR analysis of a potent decapeptide agonist of human C5a anaphylatoxin
Authors: VOGEN SHAWN M. , PRAKASH OM , KIRNARSKY LEONID , SANDERSON SAM D. , SHERMAN SIMON A.
Published: August 2010

A NMR investigation in H20, TFE and DMSO of a conformationally constrained, potent decapeptide agonist of human C5a, YSFKDMPLaR (C5a65‐74, Y65, F67, P71, d‐Ala73) showed that its N‐terminal region (YSFKD) exhibited an extended backbone conformation in H2O and a more twisted conformation in both TFE/H2O (30:70, v/v; referred to as TFE) and DMSO. The C‐terminal region (MPLaR) of the peptide adopted compact, turn‐like structures. In H2O, the C‐terminal region adopted a type II β‐turn or a distorted type V/II β‐turn involving residues PLaR. In the distorted type V/II β‐turn, Leu72 exhibited a conformation typical of a type V β‐turn, whereas D‐Ala73 exhibited a conformation typical of a type II β‐turn. The distorted type V/II β‐turn overlapped with an inverse γ‐turn involving residues MPL. In DMSO, the C‐terminal region had the analogous inverse y‐turn and the V/II γ‐turn found in H2O. In many of the DMSO structures, two inverse γ‐turns in the MPL and PLa positions formed a double‐inverse γ‐turn. None of the turns observed in H2O were present in TFE. However, in TFE, the PLa residues formed an inverse γ‐turn. Overall, the turn‐like structural motifs in the C‐terminal region of the peptide in both H2O and DMSO (but not in TFE) agreed with the biologically important conformations obtained earlier by the structure‐function analysis of a panel of C5a agonist peptides. These motifs may represent key structural elements important for C5a agonist activity and may be used to design the next generation of C5a agonist and antagonist analogues. © Munksgaard 1998.
Conformational behaviour of the TraM headpiece
Authors: PLUGARIU CARMELA , STOCKNER THOMAS , MOSKAU DETLEF , KORAIMANN GÜNTHER , HÖGENAUER GREGOR , STERK HEINZ
Published: August 2010

The structure of the headpiece of the TraM protein was investigated in different solvents. The very first 22 amino acids which alternate in their hydrophilic and hydrophobic character formed a helical structure in the presence of a membrane mimetic. In water alone the structure was flexible with a small amount of helicity according to circular dichroism measurements, whereas a loop structure was observed in dimethyl sulphoxide.
First record of host defence peptides in tadpoles. The magnificent tree frog Litoria splendida
Authors: Wabnitz P. A. , Walters H. , Tyler MJ. , Wallace J. C. , Bowie J. H.
Published: August 2010

Tadpoles of the Magnificent Tree Frog Litoria splendida produce host defence peptides early in their development and well before metamorphosis. Peptides were identified and characterized using high performance liquid chromatography and electrospray mass spectrometry. No host defence peptides were identified in the eggs. The neuropeptide caerulein was detected 10 d after egg deposition, and the antibiotic peptides caerin 1.1, caerin 1.6 and caerin 3.1 first appeared at 14 d. The concentration of peptides increases with the onset of metamorphosis at 84 d, when the host‐defence peptide profile is the same as that of the adult.
Aggregation of Aβ Alzheimer's disease‐related peptide studied by dynamic light scattering
Authors: Thunecke M. , Lobbia A. , Kosciessa U , Dyrks T. , Oakley A.E. , Turner J. , Saenger W. , Georgalis Y.
Published: August 2010

The aggregation behavior of the major component of Alzheimer's disease‐related, amyloid peptides, Aβ‐(1–40) and Aβ‐(1–42), was studied in solution using dynamic light scattering. With most solvents employed, we found fibrils coexisting with oligomeric Aβ species. Pronounced differences were observed in aggregation of Aβ‐(1–40) and (1–42) sequences in acetonitrile‐water mixtures. Cofactors such as Zn2+were found to induce deaggregation of Aβ instead of aggregation. The results indicated that the initial state of the peptide immediately after synthesis is rather poorly defined. Using freezing instead of lyophilization after the final peptide synthesis step, may partially relieve these problems.
Synthesis, solution conformation and interleukin‐6‐related activities of interleukin‐6 peptides
Authors: Bösze S. , Kajtái J. , Szabó R. , Falus A. , Hudecz F.
Published: August 2010

Interleukin‐6 (IL‐6) is a member of the cytokine superfamily characterised by a wide variety of biological activities on various cell types. IL‐6 exerts pleiotropic activities on hematopoiesis in the immune response and it is the main regulator of acute‐phase protein synthesis in liver cells. According to structure‐function studies, residues of helix A located at the N‐terminal part and/or helix D of the C‐terminal part of the protein are involved in the induction of acute‐phase responses. Two groups of synthetic peptides corresponding to the 18‐46 N‐terminal and the 168‐185 C‐terminal regions of the IL‐6 were prepared by solid‐phase synthesis to identify structural requirements for induction of fibrinogen or complement factor B synthesis. These peptides were characterised by amino acid analysis, analytical reversed‐phase high‐performance liquid chromatography, fast atom bombardment mass spectrometry, and circular dichroism (CD) spectroscopy. CD results showed that under appropriate conditions both 18‐46 and 168‐185 related peptides are able to adopt markedly ordered conformation. We demonstrated that even octapeptides from the N‐terminal part and truncated derivatives of the C‐terminal region preserved some tendency to display the CD curve of periodic conformation. The ability of the peptides to induce de novo synthesis of acute‐phase proteins was evaluated by measuring fibrinogen and complement factor B levels in the supernatants of human HepG2 cells. These results showed that residues 21‐34 are critical for eliciting fibrinogen synthesis in the presence or absence of IL‐6. In contrast, the full‐length 168‐185 peptide is required for the induction of complement factor B response.
One peptide, two topologies: structure and interconversion dynamics of human uroguanylin isomers
Authors: Marx U.C. , Klodt J. , Meyer M. , Gerlach H. , Rösch P. , Forssmann W.‐G. , Adermann K.
Published: August 2010

The peptide hormone uroguanylin stimulates chloride secretion via activation of intestinal guanylyl cyclase C (GC‐C). It is characterized by two disulfide bonds in a 1‐3/2‐4 pattern that causes the existence of two topological stereoisomers of which only one induces intracellular cGMP elevation. To obtain an unambiguous structure‐function relationship of the isomers, we determined the solution structure of the separated uroguanylin isoforms using NMR spectroscopy. Both isomers adopt well‐defined structures that correspond to those of the isomers of the related peptide guanylin. Furthermore, the structure of the GC‐C‐activating uroguanylin isomer A closely resembles the structure of the agonistic Escherichia coli heat‐stable enterotoxin. Compared with guanylin isomers, the conformational interconversion of uroguanylin isomers is retarded significantly. As judged from chromatography and NMR spectroscopy, both uroguanylin isoforms are stable at low temperatures, but are subject to a slow pH‐dependent mutual isomerization at 37°C with an equilibrium isomer ratio of approximately 1:1, The conformational exchange is most likely under the sterical control of the carboxy‐terminal leucine. These results imply that GC‐C is activated by ligands exhibiting the molecular framework corresponding to the structure of uroguanylin isomer A.
Über die Wirkung von Harnstoff und Glykokoll auf den Eiweißumsatz und die Zunahme bei wachsenden Schafen
Authors: Nehring K. , Schramm W.
Published: August 2010

Zusammenfassung der Ergebnisse

Es wurden langfristige Versuche mit wachsenden Lämmern durch‐geführt, um den Einfluß von Harnstoff und Glykokoll auf den Eiweiß‐umsatz und die Zunahmen der Tiere zu verfolgen. Es wurden hierbei etwa ⅓ der Menge an Rohprotein und etwa ½ der Menge an verdaulichem Rohprotein durch die “Amide” ersetzt. Die Ergebnisse dieser Untersuchungen lassen sich wie folgt zusammenfassen:

Eine Beeinflussung der Verdaulichkeit der verschiedenen Nähr‐stoffe durch den Zusatz von Harnstoff oder Glykokoll ließ sich nicht feststellen.

Die N‐Bilanz wurde durch die Zufütterung der Amide gegenüber der Eiweißmangelgruppe deutlich verbessert. Gegenüber der Normalgruppe bestanden nur geringe Unterschiede.

Die Untersuchungen über den Anteil der verschiedenen N‐Formen in den N‐Ausscheidungen im Harn ließen nur geringe Veränderungen erkennen. Es ließ sich eine gewisse Erhöhung des Gehalts an NH4‐N in den Amidgruppen feststellen. Der Gehalt an Hippursäure wurde nicht verändert.

Diese Untersuchungen zeigten weiterhin, daß die Tiere eine gewisse Zeit brauchen, um ihren Organismus an die Zufuhr der Amide anzupassen.

Der N‐Gehalt des Blutes wie der N‐Ansatz in der Wolle wurde durch die verschiedene Fütterung nicht beeinflußt. Die Möglichkeit einer Ausscheidung von N in gasförmigem Zustand als Ammoniak wird auf Grund der durchgeführten Untersuchungen abgelehnt.

Die Bestimmung der Schwefelbilanz ließ einen deutlichen Einfluß der Amidfütterung erkennen. Der S‐Ansatz war am geringsten in der Mangelgruppe und wurde durch die Zufütterung von Harnstoff und Glykokoll wesentlich erhöht, wenn auch die Werte der Normalgruppe nicht erreicht wurden.

Den Ergebnissen beim N‐Ansatz entsprechen die verschiedenen Gewichtszunahmen. Die geringste Zunahme war in beiden Versuchsabteilungen in der Mangelgruppe zu beobachten. Die Harnstoff‐ und besonders die Glykokollgruppe zeigten deutlich bessere Zunahmen, die nicht wesentlich von der Normalgruppe abwichen.

Die Beziehungen zwischen Gewichtszunahmen, N‐Ansatz und S‐Ansatz läß die folgende Übersicht erkennen:
Versuche über Gärfutterbereitung mit Lampes krausblättriger Futtermalve und über die Verdaulichkeit des Gärfutters bei Schafen1
Authors: Scharrer K. , Nebelsiek H.
Published: August 2010

Es wurden Einsäuerungsversuche mit Malve‐Mais‐ bzw. Malve‐Rübenblatt‐Gemischen durchgeführt. Die dabei gewonnenen Silagen wurden auf ihre Brauchbarkeit und Verdaulichkeit im Differenzverfahren unter Verwendung von Wiesenheu als Grundfutterversuch an Schafen geprüft.

Die Einsäuerung ergab, daß bei Malve‐Mais sowohl mit 0,3 wie mit 0,5 kg Biosilzusatz ein gutes Gärfutter erzielt wird. Hingegen zeigte sich bei Malve‐Rübenblatt‐Mischungen, daß ohne Sicherungszusätze und mit 0,25 kg Biosil/dz noch kein einwandfreies Gärfutter zu erhalten war. Erst durch einen Zusatz von 0,50 bzw. 1,00 kg Biosil/dz wurde ein gutes Gärfutter erreicht.

In den einzelnen Malve‐Mais‐ bzw. Malve‐Rübenblatt‐Gemischen wurden die Verdauungskoeffizienten der verschiedenen Nährstoffe und der Stärkewert ermittelt. Das Malve‐Mais‐Gärfutter mit einem Zusatz von 0,3 kg Biosil/dz wies einen verdaulichen Reinproteingehalt von 4,96% und 40,02 kg‐Stärkewert in der Trockensubstanz auf; das Malve‐Mais‐Gärfutter mit einem Zusatz von 0,5 kg Biosil/dz einen Gehalt an verdaulichem Reinprotein von 4,82% und 49,47 kg‐Stärkewert in der Trockensubstanz. Von den Malve‐Rübenblatt‐Gärfutterarten hatte Malve‐Rübenblatt + 0,5 kg Biosil/dz in der Trockensubstanz einen Gehalt von 7,30% verdaulichem Reinprotein und 42,59 kg‐Stärkewert, das Malve‐Rübenblatt‐Gärfutter mit 1,0 kg Biosil/dz in der Trockensubstanz einen Gehalt von 9,49% verdaulichem Reinprotein und 40,04 kg‐Stärkewert.

Bei Malve‐Rübenblatt‐Gärfutter wurde somit durch einen Sicherungszusatz von 0,5 kg Biosil/dz zwar ein höherer Stärkewert erzielt als bei dem Zusatz von 1,0 kg Biosil/dz; der Gehalt an verdaulichem Reinprotein war aber im letzteren Fall höher. Bei Malve‐Mais‐Gärfutter hatte der höhere Sicherungszusatz einen höheren Stärkewert zur Folge, wogegen der Gehalt an verdaulichem Reinprotein keinen Unterschied im Vergleich mit demjenigen des Gärfutters mit 0,3 kg Biosil/dz aufwies.
über die Verdauung und Resorption von Kohlenhydraten im Dickdarm der Wiederkäuer
Authors: Trautmann A. , Asher Th.
Published: August 2010

Unter Anwendung von Blinddarmkanülen wird bei der Ziege festgestellt, daß Zellulose und Stärke nach Einbringen in das Caecum den Dickdarmtraktus passieren, ohne wesentlich verändert zu werden.

Werden durch eine Labmagenkanüle nur die Vormägen ausgeschaltet, so kommt es anscheinend auch nicht zu einer nennenswerten Verdauung von eingebrachter Zellulose.

Bei Applikation von Traubenzuckerlösungen durch die Blinddarmkanüle werden selbst kleine Mengen des Zuckers (I g) nicht vollständig resorbiert; auch Rohrzucker, Malzzucker und Milchzucker lassen sich einige Stunden nach dem Eingeben in die Kanüle qualitativ in den Fäzes wieder nachweisen. Verabreichung größerer Mengen der genannten Zuckerarten führen zu Diarrhoe.

Beim „caekalen” Einlauf von Flüssigkeiten findet kein sofortiger Durchfluß durch das gesamte Colon statt. Werden größere Wassermengen zugeführt, so tritt Hämaturie ein.

Hohe intravenöse Gaben von Traubenzucker führen zu einer Exkretion von reduzierender Substanz (Traubenzucker) durch den Dickdarm.

Im Hinblick auf die funktionellen Besonderheiten des Verdauungstraktus der Wiederkäuer muß davor gewarnt werden, bei anderen Herbivorenarten (z. B. Pferd) erhobene Befunde auf die Wiederkäuer zu übertragen. In verdauungsphysiologischer Hinsicht erscheint es zweckmäßig, den Sammelnamen „Herbivoren” zu vermeiden.
Mitteilung aus der amtlichen Lebensmitteluntersuchungsstelle der Landwirtschaftlichen Versuchsanstalt Kassel‐Harleshausen Blausäuregehalt von Leinsamen
Authors: Haun F. , Leistner W.
Published: August 2010

Aus dem Schrifttum ist bekannt, daß Leinsamen und Leinsamenkuchenmehle ein Glykosid enthalten, das Blausäure abspaltet. An Proben von Leinsamen‐ und Leinsamenkuchenmehl wird festgestellt, daß die direkte Bestimmung ohne Einquellen der Probe keine wesentlichen Mengen Blausäure ergibt. Bereits nach einstündigem Einquellen mit Wasser setzt die Abspaltung der Blausäure ein. Wird zum Anfeuchten eine 1 prozent. Weinsäurelösung verwendet, ist die Abspaltung etwas geringer, beim Anfeuchten mit iprozent. Salzsäure tritt keine Blausäureabspaltung ein. Wird in einem offenen Gefäß mit Wasser aufgekocht und bleibt der Schleim offen stehen, ist etwa noch die Hälfte Blausäure in dem Schleim nachweisbar. Nach dem Anfeuchten mit Wasser und einem 18stündigen Bebrüten im geschlossenen Gefäß bei 37° entwickelten 4 Leinsamenkuchenmehle aus dem Handel sämtlich über 500 mg Blausäure (HCN) in 1 kg. Eine derartige Menge ist bedenklich und geeignet, eine schwere Erkrankung bzw. den Tod eines jungen oder schwachen Tieres herbeizuführen, wenn der stark mit Blausäure durchsetzte Brei eingegeben wird. Für eine Vergiftung durch blausäurehaltigen Leinsamenschleim ist weniger die Qualität des Samens als die Art der Zubereitung des Schleimes verantwortlich zu machen.
Die Fütterung von Glykokoll an wachsende Hammel*
Authors: Wilke Alfred
Published: August 2010

Die Ergebnisse des Versuches sind folgende:

Bei der Fütterung von Glykokoll in Gegenwart von gutem Heu und Hafer konnte das gesamte Erdnußkuchemehl der Futterration durch Glykokoll ersetzt werden. Der Gesamt‐N‐Ersatz betrug dabei 58%. Es ergaben sich dabei positive Stickstoffbilanzen bei etwa der gleichen Körpergewichtszunahme, wie sie die Fütterung mit Erdnußkuchen zur Folge hatte.

Die Ergebnisse der Schlachtversuche sprechen ebenfalls für eine eiweißsparende Wirkung des Glykokolls bei wachsenden Schafen.

Die Qualität des Fleisches leidet bei Glykokollfütterung. Das Fleisch ist weniger fest als bei normaler Fütterung, was durch höheren Wassergehalt bedingt ist.

Die Glykokollfütterung hatte eine starke Erhöhung des Säuregehaltes im Labmagen hervorgerufen.

Eine Fütterung von Glykokoll zusammen mit Stroh ließ sich nicht mit Erfolg durchführen. Die Tiere litten dabei an schweren Verdauungsstörungen, die sich durch Abnahme im Gewicht, durch unnormalen Kot, durch Futterverweigerung und durch sehr unruhiges Verhalten der Tiere äußerten.

Im Filtrat der Kotproben bei Reineiweißbestimmung nach Barnstein zeigten sich bei Glykokollfütterung Farbabweichungen gegenüber der Normalfütterung.
Stoffwechseluntersuchungen und andere ernährungsphysiologische Bestim= mungen bei Fütterung von Süßlupinen= und Inkamatklee=Grünfuttergemischen an tragende Warmblutstuten
Authors: Winkler Gerhard
Published: August 2010

Im Rahmen eines Fütterungsversuches mit grünen Zwischenfrüchten wurden auch 2 Stoffwechselbilanzen mit Pferden durchgefuhrt. Sie ergaben folgende Verdauungskoeffizienten:

Süßlupinengemeoge Inkarnatklee‐Serradella‐Gemenge

Die Verdaulichkeit des Rohproteins nach Bestimmungen aus den Frischmassen von Grünfutter und Kot liegt noch um 1,5 % höher.

Die Ausscheidung von Stoffwechselprodukten scheint in Beziehung zur aufgenommenen Grünfuttermenge, bzw. zur Trockenmassenmenge der Gesamtfuttergabe zu stehen. Dadurch wird eine Minderverdauung des Proteins bei hohen Grünfuttergaben vorgetäuscht.

Das eiweißreiche Grünfutter scheint die Verdaulichkeit des kohlenhydratreichen Beifutters erhöht zu haben.

Eine irgendwie äußerlich erkennbare Mehrbelastung der S‐Pferde durch die starken Grünfuttergaben gegenüber den H‐Pferden mit be‐schränkten, etwa normalen Grünfuttermengen konnte nicht festgestellt werden. Sie betrug 2,5 kg Trockenmasse und 14 kg Wasser je Tier und Tag.

Trotz dieser Mehraufnahme an Wasser ist der Prozentanteil der Verdunstung zur aufgenommenen Gesamtwassermenge bei S‐ und HPferden mit 32–37 % etwa gleich. Die S‐Pferde haben allerdings absolut etwa 10 kg Wasser mehr verdunstet.
Der Stärkewert der Topinamburknollen
Authors: Fingerling† Gustav
Published: August 2010

Zusammenfassung der Ergebnisse

Die Topinamburknollen wurden, soweit es ihren hauptsächlichsten Nährstoffkomponenten — die N‐freien Extraktstoffe — betrifft, von den Schweinen in demselben Ausmaß verdaut wie von den Ochsen. Bei den übrigen Nährstoffträgern zeigte sich eine kleine überlegenheit des Verdauungsvermögens der Schweine gegenüber den Ochsen.

Die nutzbare Energie der Topinamburknollen wurde von den Schweinen nicht höher zum Ansatz verwertet als von den Ochsen.

Die Topinamburknollen ‐ Trockensubstanz bewirkte infolgedessen bei den Schweinen keinen höheren Ansatz als bei den Ochsen. Da aber die Nährstoffe vollwertiger, enzymatisch abbaubarer Futtermittel von den Schweinen um rund 25–30% höher verwertet werden, so bedeutet die festgestellte gleiche Mastwirkung der Topinamburknollen beim Wiederkäuer und Schwein, daß die Nährstoffe dieser Wurzelfrucht bei ihrer Verfütterung an Schweine geringwertiger sind. Die Ursache für diese schlechtere Verwertung ist in dem chemischen Aufbau der N‐freien Stoffe der Topinamburknollen zu suchen. Während die N‐freien Stoffe der Kartoffelknollen überwiegend aus Stärke bestehen, weisen diejenigen der Topinamburknollen die Form von Lävulose auf. Es ergibt sich hieraus, daß beim Schwein der chemische Aufbau der Nährstoffe ausschlaggebend für die Nährwirkung ist. Wir haben bei unseren Versuchen mit Runkelrüben bereits nachgewiesen, daß die höhere Verwertung der Nährstoffe, wie sie in den Kartoffeln und Körnerarten enthalten sind, in der Fähigkeit der Schweine beruht, sie auf enzymatischem Wege zu verdauen — gegenüber dem Wiederkäuer, der sie bakteriell abbaut. Es muß daher aus der geringeren Wirkung der Topinamburknollen, die bei ihrer Verfütterung an Schweine in Erscheinung getreten ist, geschlossen werden, daß bei dieser Wurzelfrucht der Abbau überwiegend — wie bei den Wiederkäuern — durch Bakterien erfolgt. Dadurch werden die Nährstoffe — im Gegensatz zu den auf enzymatischer Grundlage erfolgenden Verdauungsvorgängen — in Bausteine geringeren Nährwertsabgebaut. Die Topinamburknollen gleichen daher in dieser Art des Abbaues den Runkelrüben und nicht den Kartoffeln, mit denen sie bisher in unzutreffender Weise auf Grund der ähnlichen Zusammensetzung — ermittelt nach dem Weender Verfahren — verglichen wurden.

Der Stärkewert der Topinamburknollen, der — auf 100 kg Trockensubstanz bezogen — bei den Ochsen 67,1 kg betrug, stellte sich infolge der eben besprochenen Ursachen beiden Schweinen nur auf 47,8 kg je 100 kg Trockensubstanz.
Der Gehalt an Mengen‐ und Spurenelementen in verschiedenen Kartoffel‐ und Rubensorten
Authors: Wöhlbier W. , Kirchgessner M. , Oelschläger W.
Published: August 2010

Der Gehalt an 22 verschiedenen Mengen‐ und Spurenelementen wurde in mehreren Kartoffel‐ und Rübensorten bestimmt. An Hand dieser Ergebnisse berechneten wir dann in den verschiedensten Futterrationen der Hackfruchtmast den Anteil des Spurenelement‐Sicherungszusatzes der DLG‐Mineralstoffmischung Ha an dem gesamten Gehalt an Spurenelementen der einzelnen Futterrationen. Er schwankt je nach der Futterration, je nach dem Lebensalter bei den verschiedenen Elementen zwischen 2 bis 13 % und dürfte in dieser Größenordnung nicht als ein “Sicherungszusatz” anzusprechen sein.
Life history responses to larval food shortages in four species of necrophagous flies (Diptera: Calliphoridae)
Authors: WILLIAMS H. , RICHARDSON A.M.M.
Published: August 2010

The effects of artificially reduced amounts of larval food on various life history parameters of Lucilia cuprina, Calliphora stygia, C. vicina, and C. hilli were measured to assess the likely reaction of these blowflies to competition in carrion. With increasing food shortage the puparia were reduced by up to 12% of the weight attained under conditions in which food was unlimited. The size of eggs laid by adults which had been subject to food deprivation as larvae was unchanged, but all species showed a reduction in the number of ovarioles. An index of mass‐specific reproductive investment varied considerably between the species, and the relationships between this index and the preferred habitats and dispersal strategies of the species are discussed.
The viability of seeds of rainforest species after experimental soil burials under tropical wet lowland forest in north‐eastern Australia
Authors: HOPKINS MIKES. , GRAHAM ANDREW W.
Published: August 2010

Seed samples of 50 rainforest species representative of all successional stages from tropical lowland forests in north‐eastern Australia were buried in nylon material bags under rainforest for periods up to 2 years. The seed samples were exhumed after 6 weeks, 6 months, 1 year and 2 years, and their viabilities assessed.

Substantial portions of the samples of 31 species of pioneer and early and late secondary species retained viability for 2 years in the buried samples, and germinated immediately they were exposed to greenhouse conditions. In approximately one‐third of these species, the dormancy was completely enforced by the burial conditions since fresh, mature seed germinated immediately in the greenhouse. The remainder of the long‐lived seeds showed some evidence of variable initial periods of innate dormancy produced by their hard, impermeable coats.

There was no indication that the burial conditions enforced or induced any dormancy in the seeds of primary forest trees. The mean viability of the primary forest seeds examined was 10% after 6 months burial. The soft‐coated seeds were obligate immediate germinators; they germinated or died. The remainder showed variably delayed germination, and this was interpreted as a mechanical dormancy produced by their leathery, fibrous, or stony endocarps. The group of late secondary species sampled contained both obligate immediate germinators and seeds with well developed dormancy mechanisms.

Many of the buried 'seedlings’ of primary forest species remained alive for a year or more attached to seeds, demonstrating the ability of the larger primary seeds to sustain seedlings under conditions adverse to photosynthesis and growth. Some seedlings of Castanospermum australe were alive and were transplanted successfully after 2 years burial. This enables primary forest species to stock seedlings on the forest floor in contrast to the secondary species which store seed in the soil.