bluuebunny/crossref_metadata_2025 huggingface dataset:
X‐ray structures of aza‐proline‐containing peptides
Authors: DIDIERJEAN CLAUDE , DUCA VALERIO DEL , BENEDETTI ETTORE , AUBRY ANDRÉ , ZOUIKRI MOHAMED , MARRAUD MICHEL , BOUSSARD GUY
Published: August 2010

The aza‐analogue of proline (AzPro) contains a nitrogen atom in place of the CHα of the cognate residue. The resolution of the crystal structures of seven AzPro‐containing peptides, presenting a set of ten AzPro motifs, reveals the structural properties of this particular aza‐residue. Because of sterical hindrances, both nitrogen atoms are out of planarity, and the reduced electronic conjugation in the two AzPro‐adjacent amide groups probably explains the longer amide bond distances and the weak proton‐accepting character of the two pyrazolidine nitrogens. The absolute configuration of both AzPro nitrogens depends on the chemical nature of the sequence. In all cases, the AzPro residue assumes the same intrinsic three‐dimensional structure and presents folding tendencies opposed to those induced by proline.
Interaction of lipophilic peptides derived from mastoparan with phospholipid vesicles
Authors: NIIDOME TAKURO , KAWAKAMI RIE , OKAMOTO KINYA , OHMORI NAOYA , MIHARA HISAKAZU , AOYAGI HARUHIKO
Published: August 2010

Various kinds of lipophilic peptides were prepared by acylation of an ct‐helical peptide, mastoparan, to investigate the effects of acyl groups on the interaction of peptides with phospholipid membranes. α‐Helicity of the peptides was increased by introduction of long acyl groups. Acyl peptides showed different membrane‐perturbation activities for neutral and acidic phospholipid vesicles, whereas a peptide with a dialkycarbamoyl group always exhibited a strong activity. High hemolytic activities were observed for the peptides with long acyls (single or double chain). These results indicate that lipophilic groups introduced to mastoparan contribute greatly to the interaction of the peptide with phospholipid membranes with lengthening of the acyl chain and that the structural character of the lipophilic group also influences the conformation of the peptide.
Peptides corresponding to the second epidermal growth factor‐like domain of human blood coagulation factor VII: synthesis, folding and biological activity
Authors: HUSBYN METTE , ÖRNING LARS , SAKARIASSEN KJELL S. , FISCHER PETER M.
Published: August 2010

Factor VIIa (FVIIa) is the enzymatically active constituent of the FVIIa/tissue factor (TF) complex, the initiator of the extrinsic pathway of blood coagulation. The zymogen FVII and FVIIa are composed of discrete domains, two of which are homologous to the epidermal growth factor (EGF). This investigation examined the significance of the FVII EGF‐2 domain in the processes leading to activation of factor X (FX). Peptides 47 residues in length and corresponding to the amino acid sequence of the EGF‐2 domain of human FVII were prepared by solid‐phase synthesis methods. Peptide variants with all six Cys residues replaced by l‐2‐aminobutyryl residues (1), or containing one (2a‐c), two (3a,b) or three (4) disulfide bonds, were obtained by application of various S‐protecting groups and oxidation methods. Peptide 4, containing the cystine bridge arrangement corresponding to that found in the native protein, was prepared by a two‐step regioselective disulfide bond formation method. An evaluation of the anti‐coagulant properties of peptides 1‐4 revealed that all peptides, with the exception of the two‐cystine isomer containing non‐native disulfide pairings (3b), were potent inhibitors of TF/FVIIa‐mediated activation of FX. The fully constrained peptide 4 was found to be twice as active as its completely non‐constrained counterpart 1, the two peptides showing IC50 values of 1.6 ± 0.5μm (1) and 0.8 ± 0.2 μm (4) with respect to TF/FVIIa‐dependent FX activation. The results of this study demonstrate the functional importance of the EGF‐2 domain of FVII in the induction of coagulation by the extrinsic pathway.
Synthesis of phosphotyrosine‐containing peptides using bis‐(2, 2, 2‐trichloro)ethyl groups for phosphate protection
Authors: PAQUET ALENKA , BLACKWELL BARBARA , JOHNS MICHAEL , NIKIFORUK JOHN
Published: August 2010

Suitability of bis‐(2, 2, 2‐trichloro)ethyl (Tc) groups for protection of phosphate moiety in Boc‐mode synthesis of phosphotyrosine peptides is demonstrated Boc‐Tyr(PO3 Tc2)‐OH and Fmoc‐Tyr(PO3Tc2)‐OH were prepared by acylating H‐Tyr(PO3Tc2)‐OH with (Boc)2O and Fmoc‐ONSu, respectively. Phosphorus introduction was achieved by phosphorylating Boc‐Tyr‐OBzl with Tc phosphochloride. The Tc‐phosphorus protector was found to be incompatible with the Fmoc group because the conditions of Fmoc removal (piperidine treatment) caused dephosphorylation. Complete NMR spectral assignments in the described compounds is presented. (Contribution No. 2398 from the Centre for Food and Animal Research).
Synthesis and study of normal, enantio, retro, and retroenantio isomers of cecropin A‐melittin hybrids, their end group effects and selective enzyme inactivation
Authors: VUNNAM SATYANARAYANA , JUVVADI PADMAJA , ROTONDI KENNETH S. , MERRIFIELD R. B.
Published: August 2010

In our effort to understand the structural requirements for the antimicrobial activity of cecropin A (CA) and melittin (M), we synthesized the normal, enantio, retro and retroenantio hybrid analogs; we related activity to their sequence, chirality, amide bond direction (helix dipole) and end group charges. To compare the effect of the end groups, each of these analogs was synthesized both with an acid and an amide C‐terminus and also with and without an Nα‐acetyl N‐terminus.

The all‐l‐ and all‐d‐enantiomers of several cecropin‐melittin hybrids were previously found to be equally potent against several bacterial species, and no chiral effect was observed. This general rule has now been confirmed and extended. However, two exceptions have been found. All‐l‐CA(1‐13)M(1‐13) acid was 5 times and 9 times less potent than the all‐d‐analog, respectively, toward Gram‐positive Staphylococcus aureus and Gram‐negative Pseudomonas aeruginosa. A11‐l‐CA(1‐7)M(2‐9) acid was 5 times and 14 times less active against S. aureus and P. aeruginosa, respectively, than its all‐d acid isomer. The corresponding d‐ and l‐retro analogs differed only marginally. A role for proteolytic enzymes has been implicated as a cause for these differences in the activities of l‐ and d‐enantiomers. In all cases, blocking the α‐amine by acetylation had no significant effect on potency.

The retro and retroenantio analogs of CA(1‐13)M(1‐13) acid were as potent as their normal and enantio analogs against all the test bacteria. The C‐terminal amides also showed similar potency against four test bacteria. It should be noted that the negative end of the helix dipole of a normal peptide points toward the C‐terminus, whereas it points away in the case of a retro derivative when viewed in the direction of the normal sequence.
Synthesis of thioredoxin partial sequences on 1,6‐hexanedioI diacrylate (HDODA)‐cross‐linked polystyrene resin
Authors: VARKEY JAYA T. , PILLAI V. N. RAJASEKHARAN
Published: August 2010

The continued and rapid discoveries of new peptides with interesting biological functions have created an unprecedented demand for the chemical synthesis of peptides required for structure‐function correlations. Several strategic improvements have been suggested and tested to meet the demand for peptides in high purity and quantity. This article describes the synthesis of three partial sequences of thioredoxin, a naturally occurring sulfur‐reducing protein containing 108 amino acid residues, on a newly developed flexible, cross‐linked polystyrene support (2% polystyrene cross‐linked with 1,6‐hexanediol diacrylate) using the standard solid‐phase methodology. The protected peptides were cleaved from the polymeric support by trifluoroacetic acid and purified by chromatography. The free peptides were shown to be homogeneous by high‐performance liquid chromatography and were characterized by amino acid analysis and circular dichroism. The circular dichroism measurement revealed that the peptides possess a helical conformation. From the yield and purity of the peptides obtained, it was inferred that the favorable swelling and solvation characteristics of the support facilitated effective synthesis.
Interruption of T‐cell signal transduction by lentivirus lytic peptides from HIV‐1 transmembrane protein
Authors: BEARY TIMOTHY P. , TENCZA SARAH BURROUGHS , MIETZNER TIMOTHY A. , MONTELARO RONALD C.
Published: August 2010

Two peptide segments designated LLP1 (residues 828‐855) and LLP2 (residues 768‐788) of the HIV‐1 transmembrane (TM) envelope protein display structural and functional properties of calmodulin (CaM) binding. These LLP segments may contribute to cytopathogenesis by binding cellular CaM and inhibiting normal CaM‐regulated signal transduction pathways. To determine whether these peptides could interrupt signal transduction in vivo, a cellular assay which uses a reporter gene linked to the nuclear factor of activated T cells (NF‐AT) was used. Signal transduction perturbation was tested by exogenous addition of LLPs, W‐7 or ionomycin; the LLPs inhibited NF‐AT‐mediated signal transduction as measured by reduced reporter activity. The LLP inhibition profile of NF‐AT‐driven luciferase activity was similar to the CaM inhibitor W‐7. This was in direct contrast to ionomycin, a mobile calcium ion carrier which caused a significant increase in luciferase activity. These findings are consistent with the hypothesis that the CaM‐binding properties of TM may contribute to defects in signal transduction leading to the T‐cell anergy observed in patients infected with HIV‐1.
Peptides derived from human C‐reaetive protein inhibit the enzymatic activities of human leukocyte elastase and cathepsin G: use of overlapping peptide sequences to identify a unique inhibitor
Authors: YAVIN ERAN J. , FRIDKIN MATI
Published: August 2010

Ten overlapping 15‐mer peptides, spanning the entire inner disulfide loop of human C‐reactive protein (residues 36‐97), were used to isolate a potent inhibitor of the enzymes human leukocyte elastase and human leukocyte cathepsin G, which are associated with chronic inflammatory tissue damage. In contrast to the inability of intact C‐reactive protein to inhibit both enzymes, the synthetic peptide E62ILIFWSKDIGYSFT76 inhibited leukocyte elastase (Ki= 0.18 μm) and cathepsin G (Ki= 0.25 μm) at concentrations far lower than the acute‐phase concentration of C‐reactive protein. Several peptide‐enzyme binding motifs were elucidated by structure‐function studies, with the Glu62 residue being crucial in establishing long‐range subsite interactions. Peptides derived from C‐reactive protein, which may be generated in vivo by neutrophil‐mediated proteolysis as part of a complex regulatory homeostatic mechanism, may play an important role in regulating the activity of matrix‐degrading enzymes, specifically at sites of inflammation. The present results thus may shed additional insight on the physiological functions of the major acute‐phase reactant C‐reactive protein, and perhaps be used as a basis for the design of novel therapeutic substances.
Three‐dimensional structure of the Y1 receptor agonist [Leu31, Pro34]NPY as determined by NMR and molecular modeling
Authors: KHIAT ABDESSLEM , LABELLE MARTIN , BOULANGER YVAN
Published: August 2010

The solution structure of the Y1 receptor agonist, porcine [Leu31, Pro34]NPY, has been investigated by two‐dimensional NMR and molecular modeling. A complete assignment of the NMR resonances was achieved and 201 inter‐residue nuclear Overhauser enhancement spectroscopy (NOESY) connectivities could be identified, comprising several connectivities between the N‐ and C‐terminal segments. A molecular model was calculated by distance geometry, simulated annealing and conjugate gradients energy minimization using the NOE constraints. The results indicate that, like NPY and other peptides of the family, [Leu31, Pro34]NPY adopts a folded hairpin structure with the terminal segments in close proximity. Analysis of the secondary chemical shifts for the CHα's and of the temperature dependence of the NH chemical shifts combined with the NOE constraints indicates a tendency toward helix structure for the segment 18‐30 and the presence of turn structure for the C‐terminal segment (residues 31‐36). Native NPY and [Leu31, Pro34]NPY have most of their structures in common but differ slightly in their C‐terminal portion. Based on the structures of NPY and of its specific agonists, [Leu31, Pro34]NPY and NPY 13‐36, conclusions can be drawn about the structural requirements for binding to the Y1 and Y2 receptor subtypes.
Alzheimer's β‐amyloid peptide: affinity for metal chelates
Authors: BALAKRISHNAN R. , PARTHASARATHY R. , SULKOWSKI E.
Published: August 2010

Alzheimer's amyloid peptide, Aβ(1‐42) and its fragments, Aβ(1‐28) and Aβ(1‐16), were chromatographed on IDA‐M(II) columns (M: Cu2+, Ni2+ and Zn2+). The retention of Aβ(1‐42) and its fragments on IDA‐Cu(II) could not be reversed in decreasing a gradient of pH, from 7.0 to 4.0. All Aβ peptides were recovered from IDA‐Ni(II) columns in a decreasing pH gradient from 7.0 to 4.0, within the pH range from 5.6 to 5.1. Aβ(1‐42) peptide was strongly retained on IDA‐Zn(II) at pH 4.0, but it's aβ(1‐28) and Aβ(1‐16) were only transiently retained on IDA‐Zn(II) columns when applied at pH 6.1. We submit that histidine clusters, residing both in the Alzheimer's β‐amyloid peptide and in most of the APP/APLP superfamily of proteins, constitute high‐affinity binding sites for immobilized metal chelates.
New analogs of human growth hormone‐releasing hormone (1‐29) with high and prolonged antagonistic activity
Authors: TOTH KATALIN , KOVACS MAGDOLNA , ZARANDI MARTA , HALMOS GABOR , GROOT KATE , NAGY ATTILA , KELE ZOLTAN , SCHALLY ANDREW V.
Published: August 2010

Based on our previous results, in conjunction with various structural considerations, 19 new analogs of the GHRH antagonist [PhAc‐Tyr1,D‐Arg2,Phe(pCl)6,Abu15,Nle27,Agm29]hGHRH(1‐29) (MZ‐5‐156) were synthesized by the solid‐phase method. These compounds were designed to develop further analogs of this class with increased receptor‐binding affinity. All analogs had Abu15 and Nle27 modifications and were acylated with phenylacetic acid at the N‐terminus. Most of the analogs had d‐Arg2 and Phe(pCl)6 substituents and Agm29 or Arg29‐NH2 at the C‐terminus. Additional single substitutions consisted of the incorporation of d‐ or l‐Tic1, d‐Tic2, Tic6 or Phe(pNO2)6 and Arg29‐NH2. The Arg29‐NH2 analog of MZ‐5‐156 (KT‐48) was further modified by single substitutions using Pal1; d‐Tpi2; d‐ or l‐Phe4; Phe(pX)6×= F, Cl, I; Tyr7; Aib8; Tyr(Me)10 or Phe(pCl)10. Four peptides had multiple substitutions. All the analogs were evaluated for their ability to inhibit GH release induced by hGHRH(1‐29)NH2in vitro and some were also tested in vivo. Peptides [PhAc‐Tyr1,D‐Arg2,Phe(pI)6,Abu15,Nle27]hGHRH(1‐29)NH2 (KT‐30), [PhAc‐Tyr1,D‐Arg2,Phe(pCl)6,Aib8,Abu15,Nle27]hGHRH(1‐29)NH2 (KT‐50) and [PhAc‐Tyr1,D‐Arg2,Phe(pCl)6,Tyr(Me)10,Abu15,Nle27]hGHRH(1‐29)NH2 (KT‐40) with Phe(pI)6, Aib8 or Tyr(Me)10modifications, respectively, showed high and prolonged inhibitory effect in superfused rat pituitary system. Analog KT‐50 also exhibited a strong and long‐term inhibitory activity in vivo in rats. Most of the new analogs showed high binding affinities to rat pituitary GHRH receptors.
Synthesis and stabilization of amino and carboxy terminal constrained collagenous peptides
Authors: TANAKA YUJI , SUZUKI KAZUO , TANAKA TOSHIKI
Published: August 2010

Short collagenous peptides cross‐linked at their amino and carboxy termini with Lys‐Lys‐dimer template(s) were synthesized, and the effect of the cross‐linking on their stabilities was investigated by thermal denaturation experiments. Two chemoselective ligations were used for the construction of the amino and the carboxy cross‐linked peptides. The thermal transition temperature (Tm) and the standard free energies (ΔG°) of the cross‐linked collagenous peptides increased, and the thermal stabilization effect corresponded to an elongation by two units of the Gly‐Pro‐Hyp triad. The van't Hoff enthalpy (ΔH°) and the entropy (ΔS°) values of the cross‐linked peptides increased with chain elongation, although the increments were smaller than those of the linear peptides. When the same chain lengths were compared, the ΔH° was increased and the ΔS° was nearly the same or increased by the cross‐linking. These results suggest that the cross‐linking of the collagenous peptides with the Lys‐Lys‐dimer template(s) for stabilization contributes to the enthalpic effect, rather than the entropic effect.
NMR and quenched molecular dynamics studies of superpotent linear and cyclic α‐melanotropins
Authors: AL‐OBEIDI FAHAD , O'CONNOR STEVEN D. , JOB CONSTANTIN , HRUBY VICTOR J. , PETTITT B. MONTGOMERY
Published: August 2010

Conformational searching, computer simulations, synthesis and NMR are used on a variety of α melanocyte‐stimulating hormone (α‐MSH) analogues to understand the physical characteristics required for biological potency. Peptides I (AC‐[Nle4,Asp5,d‐Phe7,Lys10]α‐MSH(4‐10)‐NH2), II (Ac‐c[Nle4,Asp5,d‐Phe7,Lys10]α‐MSH(4‐10)‐NH2) and III (Ac‐[Nle4,Asp5,d‐Phe7,Dap10]α‐MSH(4‐10)‐NH2all show very similar conformational properties (backbone and side‐chain torsional angles), and all display high biological potencies. The modeling results for these compounds are supported by the NMR data. Peptide IV (Ac‐c[Nle4,Asp5,d‐Phe7,Dap10]α‐MSH(4‐10)‐NH2) appears to have a markedly different conformation and has decreased biological potency.
A comparative conformational analysis of thimet oligopeptidase (EC 3.4.24.15) substrates
Authors: JACCHIERI S. G. , GOMES M. D. , JULIANO L. , CAMARGO A. C. M.
Published: August 2010

The specificity of thimet oligopeptidase (EC 3.4.24.15) (TOP 24.15) does not agree with theoretical models devised to explain the specificity characteristic of peptidases toward certain sequences of amino acid residues. According to previous studies peptide chains hydrolyzed by TOP 24.15 adopt similar main chain conformations, although with different and in some cases small probabilities of occurrence in aqueous solution. To determine specific structural features recognized by TOP 24.15, a conformational search including eight polypeptides with known susceptibilities for catalytic hydrolysis was executed and the distribution of each main chain conformation found in the search was tabulated. Two sets of main chain conformations were selected, those common to all peptides in the study and those common only to substrates of TOP 24.15. The former set is very small and includes mainly extended conformations. In contrast, the latter set is large and its conformations are coiled and exhibit sharp turns coincident with positions of hydrolysis by TOP 24.15. These results indicate a possible basis for the selectivity of TOP 24.15.
RGDS glycosylated peptides as inhibitors of cell‐attachment and platelet aggregation
Authors: Harth‐Fritschy E. , Dufour S. , Si‐Tahar M. , Chignard M. , Biberovic V. , Cantacuzène D.
Published: August 2010

Abstract: Glycopeptides derived from the GRGDS sequence were synthesized to study the effect of the sugar residue on the activity of these peptides. The peptides were tested as inhibitors of cell adhesion to fibronectin and of platelet aggregation. The sugar moiety was found to reduce the biological activity of the parent compounds except for the cyclic derivatives P37 and P38 where the inhibition of platelet aggregation was increased. Some interesting differences were observed between the peptides bearing sugar residues with free hydroxyl groups and those with peracetylated sugars.
Analytical techniques and computer algorithms combined for the rapid characterization of structural peptide and protein features
Authors: Caporale C.
Published: August 2010

Abstract: The most recent algorithms based on the use of modern analytical techniques for the assessment of structural peptide and protein features have been reviewed. No algorithm devoted to the realization of predictive models or statistical analysis has been discussed, but only methods furnishing information on the real structure of the molecules. In particular, the procedures designed for handling sequence and mass spectrometric data obtained from the analysis of unfractionated digestion mixtures allow the user to get rapid information on the structure of the target polypeptide. Two classes of methods are illustrated: the first regards the determination of the amino acid sequence, whereas the second used its knowledge to supply data on the localization, function and three‐dimensional structure of disulphides.
Structure and property of model peptides of proline/arginine‐rich region in bactenecin 5
Authors: NIIDOME TAKURO , MIHARA HISAKAZU , OKA MASAHITO , HAYASHI TOSHIO , KAZUTOSHIYOSHIDA TETSUNOBU SAIKI , AOYAGI HARUHIKO
Published: August 2010

Bactenecin 5 (Bac 5), a cationic antibacterial peptide, contains a repeating region of Arg‐Pro‐Pro‐X (X = hydrophobic residue). To investigate the structure and property of a Pro/Arg‐rich region, we synthesized a series of repeating peptides, Ac‐(Arg‐Pro‐Pro‐Phe)n‐NHCH3 (n = 2, 4, 6, 8 and 10) (PR2, PR4, PR6, PR8 and PR10,) as models. The circular dichroism (CD) study suggested that the peptides with longer repeats, PR6, PR8 and PR10, formed a conformation similar to poly(proline)‐II in aqueous solution. The CD spectra did not change in the presence of dipalmitoyl‐d‐α‐phosphatidylcholine (DPPC), but they changed in the presence of DPPC/dipalmitoyl‐dl‐3‐phosphatidylglycerol (DPPG). The γ‐helix, which is very similar in conformation to the poly(proline)‐II helix, had the lowest energy conformation for the peptides by energy calculations. Peptides PR6, PR8 and PR10 caused slight leakage of fluorescent dye entrapped in DPPC vesicles, and in the presence of DPPCDPPG, these peptides showed a considerable level of dye‐leakage activity. In contrast, the shorter peptides PR2 and PR4 showed no activity. The same tendency was found in measurements of membrane‐fusion activity. Judging from these results, the repeating region of Bac 5 may make a framework to hold a conformation resembling the poly(proline)‐II structure in aqueous solution. In addition, this region may interact with acidic lipids, resulting in a change in conformation of the peptide. © Munksgaard 1998.
Chemical synthesis of dendrotoxin‐I: revision of the reported structure
Authors: NISHIO HIDEKI , INUI TATSUYA , NISHIUCHI YUJI , MEDEIROS CLEANE L.C. DE , ROWAN EDWARD G. , HARVEY ALAN L. , KATOH ETSUKO , YAMAZAKI TOSHIMASA , KIMURA TERUTOSHI , SAKAKIBARA SHUMPEI
Published: August 2010

Dendrotoxin I (DTX‐I) is a 60‐residue peptide from the venom of the black mamba snake Dendroaspis polylepis, which binds to neuronal K+ channels. The structure reported previously for DTX‐I was synthesized for the first time by a solution procedure. The synthetic product was confirmed to have the correct primary and disulfide structure determined by peptide mapping, sequence analysis and mass measurements. Comparison of synthetic DTX‐I with the natural one by high‐performance liquid chromatography and capillary zone electrophoresis, as well as by sequence analysis, revealed that the Asn residue at position 12 in the synthetic peptide was Asp in the natural product. Synthesis of DTX‐I with Asp at position 12 gave a peptide identical with the natural product in all aspects. NMR analysis of synthetic [Asn12]. ‐ and [Asp12]. ‐DTX‐I also supported our findings that the Asn residue at position 12 in the DTX‐I molecule should be revised as Asp. [Asn12]. ‐ and [Asp12]. ‐DTX‐I had very similar binding affinities when tested against radiolabeled dendrotoxin binding to rat brain synaptosomal membranes. © Munksgaard 1998.
Molecular recognition of cobalt(III)‐ligated peptides by serine proteases: The role of electrostatic effects
Authors: Bagger S. , Wagner K.
Published: August 2010

A series of peptides with a positively charged cobalt(III)‐complex group attached to the carboxylate terminal was synthesized. The behavior of these metallopeptides as acceptor nucleophiles in acyl transfer reactions catalyzed by the three serine proteases bovine pancreatic α‐chymotrypsin, porcine pancreatic trypsin, and proteinase K from Tritirachium album was examined. The efficiency of the substrates was assessed by kinetic measurement of the partition between aminolysis and hydrolysis. The results are discussed with special reference to coulombic interactions between the metal‐ligated substrates and charged residues on the enzyme surfaces. The idea of using the metallopeptides in practical enzymatic peptide synthesis is put forward.
Role of conformational constraints of position 7 of the disulphide bridge of h‐α‐CGRP derivatives in their agonist versus antagonist properties
Authors: Saha S. , Waugh D.J.J. , Zhao P. , Abel P.W. , Smith D.D.
Published: August 2010

Previous structure‐activity studies have shown that the disulphide bridge of calcitonin gene‐related peptide (CGRP) is important for the highly potent, CGRP receptor‐mediated effects of this peptide. In this study penicillamine (Pen) was substituted for one or both of the cysteinyl residues to determine conformational and topographical properties of the disulphide bridge favourable for binding to CGRP receptors and/or receptor activation. Pen constrains the conformational flexibility of disulphide bridges in other peptides. Binding affinities were measured using a radioligand binding assay with membranes prepared from pig coronary arteries and125l‐h‐α‐CGRP. Functional effects were characterized using a previously reported pig coronary artery relaxation bioassay. The binding affinity of (Pen125]‐h‐α‐CGRP was not significantly different from that of h‐α‐CGRP. All other analogues showed reduced affinity for CGRP receptors. [Pen2)‐h‐α‐CGRP also caused relaxation of coronary arteries. The remaining analogues either caused relaxation with significantly reduced potency or failed to relax the arteries at concentrations up to 1 × 10‐−5M. All analogues that did not relax coronary arteries contained a D‐Pen in position 7 and inhibited CGRP‐induced relaxation. [D‐Pen2,7]h‐α‐CGRP was the most potent antagonist with aKB, value of 630 nM. This affinity is similar to that of the classical CGRP receptor antagonist, h‐α‐CGRP(8‐37), on these arteries (KB, 212 nM). These studies show that modifying the topography of the disulphide bridge can cause large and variable effects on ligand binding and activation of CGRP receptors. The contribution of position 7 to the conformation and topography of the disulphide bridge of h‐α‐CGRP is crucial to the future design of agonists of CGRP receptors. Furthermore, position 7 is important for the development of new CGRP receptor antagonists with structures based on the whole sequence of h‐α‐CGRP.
Contribution to the synthesis of aureobasidin A. Synthesis of cyclopeptolides containing the sequence leucyl‐N‐methyl‐β‐hydroxyvalyl‐ (2R)‐oxy‐(3R)‐methyl‐pentanoic acid *
Authors: Schmidt U. , Schumacher A. , Mittendorf J. , Riedl B.
Published: August 2010

The efficient antimycotic agent aureobasidin A, isolated from the culture broth of Aureobasidium pullulans R 106, and the [(R)‐Pro9]‐aureobasidin A were prepared starting from benzyl N‐Boc‐N‐methyl‐(S)‐β‐triethylsiloxyvalinate, the synthesis of which is described here. The easy accessibility of the tripeptolide benzyl Boc‐leucyl‐N‐methyl‐β‐hydroxyvalyl‐(2R)‐oxy‐(3R)‐methylpentanoate [Boc‐Leu‐HOMeVal‐(R)‐HMP‐OBn] facilitates the construction of the cyclopeptolides 28, 34, 45 and 47. The peptide bonds of the N‐methylamino acids were formed with the help of O‐(7‐azabenzotria‐zol‐1‐yl)‐1,1,3,3‐tetramethyluronium hexafluorophophate. The rings of [(R)‐Pro9]‐aureobasidin A and of cyclopeptolides 28, 34, 45 and 47 were closed by way of pentafluorophenyl esters. The ring of aureobasidin A could only be formed with bromo‐tris‐pyrrolidino‐phosphonium hexafluorophosphate.
A concise methodology for the stereoselective synthesis of O‐glycosylated amino acid building blocks: complete 1HNMR assignments and their application in solid‐phase glycopeptide synthesis
Authors: Satyanarayana J. , Gururaja T.L. , Naganagowda G.A. , Ramasubbu N. , Levine M.J.
Published: August 2010

A facile strategy for the stereoselective synthesis of suitably protected O‐glycosylated amino acid building blocks, namely, Nα‐Fmoc‐Ser‐[Ac4‐β‐d‐Gal‐(1‐3)‐Ac2α or β‐d‐GalN3]‐OPfp and Nα‐Fmoc‐Thr‐[Ac4‐β‐d‐Gal‐(1‐3)‐Ac2‐α or β‐d‐GalN3]‐OPfp is described. What is new and novel in this report is that Koenigs‐Knorr type glycosylation of an aglycon serine/threonine derivative (i.e. Nα‐Fmoc‐Ser‐OPfp or Nα‐Fmoc‐Thr‐OPfp) with protected β‐d‐Gal(1‐3)‐d‐GalN3 synthon mediated by silver salts resulted in only α‐and/or β‐isomers in excellent yields under two different reaction conditions. The subtle differences in stereoselectivity were demonstrated clearly when glycosylation was carried out using only AgClO4 at ‐40°C which afforded α‐isomer in a quantitative yield (α:β= 5:1). On the other hand, the β‐isomer was formed exclusively when the reaction was performed in the presence of Ag2CO3AgClO4 at room temperature. A complete assignment of 1H resonances to individual sugar ring protons and the characteristic anomeric α‐1H and β‐1H in Ac4Galβ(1‐3)Ac2GalN3α and/or β linked to Ser/Thr building blocks was accomplished unequivocally by two‐dimensional double‐quantum filtered correlated spectroscopy and nuclear Overhauser enhancement and exchange spectroscopy NMR experiments. An unambiguous structural characterization and documentation of chemical shifts, including the coupling constants for all the protons of the aforementioned a‐ and p‐isomers of the O‐glycosylated amino acid building blocks carrying protected β‐d‐Gal(1‐3)‐d‐GalN3, could serve as a template in elucidating the three‐dimensional structure of glycoproteins. The synthetic utility of the building blocks and versatility of the strategy was exemplified in the construction of human salivary mucin (MUC7)‐derived, O‐linked glycopeptides with varied degrees of glycosylation by solid‐phase Fmoc chemistry. Fmoc/tert‐butyl‐based protecting groups were used for the peptidic
Crystal structure of Boc‐LAla‐ΔPhe‐ΔPhe‐ΔPhe‐ΔPhe‐NHMe: a left‐handed helical peptide
Authors: Ramagopal U. A. , Ramakumar S. , Joshi R. M. , Chauhan V. S.
Published: August 2010

αβ‐Dehydrophenylalanine residues constrain the peptide backbone to β‐bend conformation. A pentapeptide containing four consecutive (APhe) residues has been synthesised and crystallised. The peptide Boc‐LAla‐ΔPhe‐ΔPhe‐ΔPhe‐ΔPhe‐NHMe (C45H46N6O7, MW = 782.86) was crystallised from an acetonitrile/ methanol mixture. The crystal belongs to the orthorhombic space group P212121 with a = 19.455(6), b = 20.912(9), c = 11.455(4) Å and Z = 4. The X‐ray (MoKα, lD = 0.7107 Å) intensity data were collected using the Rigaku‐AFC7 diffractrometer. The crystal structure was determined by direct methods and refined using the least‐squares technique, R = 8.41% for 1827 reflections with ‖F0‖ > 4σ‖Fo‖. The molecule contains the largest stretch of consecutive dehydrophenylalanine residues whose crystal structure has been determined so far. The peptide adopts left‐handed 310‐helical conformation despite the presence of LAla at the N‐terminus. The mean ø, Ψ values, averaged across the last four residues are 56.8° and 17.5°, respectively. There are four 41 intramolecular hydrogen bonds, characteristic of the 310‐helix. In the crystal each molecule interacts with four crystallographically symmetric molecules with one hydrogen bond each.
Conformational studies of a potent Leu11, D‐Trp12‐containing lactam‐bridged parathyroid hormone‐related protein‐derived antagonist
Authors: Maretto S. , Schievano E. , Mammi S. , Bisello A. , Nakamoto C. , Rosenblatt M. , Chorev M. , Peggion E.
Published: August 2010

Human parathyroid hormone‐related protein (PTHrP) is expressed in various tissues where it acts as an endocrine/paracrine factor involved in cellular growth, differentiation and development of fetal skeleton. As for parathyroid hormone (PTH), which is the hormone responsible for regulation of extracellular calcium homeostasis, the N‐terminal 1‐34 fragment can reproduce the full spectrum of calciotropic activities inherent in full‐length PTH. Truncation of six amino acid residues from the N‐terminus of both hormone sequences generates 7‐34 fragments which act as weak antagonists. Although PTH(7‐34) is a pure antagonist, PTHrP(7‐34) acts as partial agonist against the receptor shared by both hormones, the PTH/PTHrP receptor. In the current study, we analyzed the conformation of [Leu11,d‐Trp12,Lys26,Asp30]PTHrP(7‐34)NH2 (hybrid‐lactam) in a 1:1 mixture of H2O/TFE‐d3 at pH 4 by circular dichroism, nuclear magnetic resonance and distance geometry calculations. This weak antagonist (Kb= 650 nm) combines two modifications: Leu11,d‐Trp12 (Kb= 5.1 nm), reported to eliminate partial agonism and enhance potency, and Lys26‐Asp30 lactamization (Kb= 31 nm), aimed to stabilize the helical structure of the principal binding domain attributed to residues 25‐34. The helical content in 30% trifluoroethanol is 88%, i.e., higher than the corresponding linear analog, and comprises the d‐Trp12‐Thr33 segment. This hybrid lactam contains a rigid helical segment spanning the 14‐18 sequence followed by a hinge motif around Arg19‐20, but the sequence 14‐18 forms a stable helix. In all potent lactam‐containing, PTHrP‐derived agonists and antagonists studied so far, the dominant structural motif consists of two helical domains at the two ends of the sequence and of two hinge regions centered around Gly12‐Lys13 and Arg19. The weakly active agonists and antagonists do not exhibit the “hinge” around position 19. These findings suggest that the presence and location of discrete hinge regions that connect the N‐ and C‐terminal helices are essential for generating the bioactive conformation of ligands for the PTH/ PTHrP receptor.
Neues Verfahren zur Ermittlung des Weideertrages*
Authors: Kienle A.
Published: August 2010

Um die Schwierigkeiten, die sich bei der erstgenannten Methode zur Errechnung der von Weidetieren aufgenommenen Futtermengen im Zusammenhang mit der Aufstellung einer zweiten Tiergruppe zur Ermittlung der V.‐C. ergeben, wurde noch eine andere Möglichkeit der Futtererrechnung verfolgt. Wir suchten nach einem Stoff, der quantitativ unverändert den Verdauungsapparat durchwandert, so daß also dessen Menge im Kot mit der im Futter identisch wäre und folglich nach Bestimmung dessen Anteiles am Gesamtfutter, dieses selbst leicht errechnet werden könnte. Nach Untersuchungen von Kühn, Morgen u. a. sollten im Futter und Kot gleiche Mengen an pepsin‐HCl‐unlöslichem N vorkommen, weshalb wir diesen Weg dann weiter verfolgten. Im Laufe der diesbezüglichen Versuche stellte sich nun heraus, daß die Höhe der künstlichen Verdauung weitgehend vom Feinheitsgrad der Analysensubstanz abhängig ist. In unserem Fall sind aber brauchbare Ergebnisse nur dann zu erzielen, wenn alle Werte unter genau denselben Verhältnissen erhalten werden, d. h. wenn alle Analysensubstanzen genau denselben Feinheitsgrad aufweisen. Da wir es jedoch mit frischen Substanzen zu tun hatten, die kein Mahlen zuließen und da außerdem auch beim Mahlen der getrockneten Substanzen in der üblichen Weise sich immer noch gewisse Unterschiede in der Feinheit zeigten, so blieb als der sicherste Weg der, alle Proben, die der Verdaulichkeitsbestimmung dienten, in den höchstmöglichen Feinheitsgrad zu überführen. Dies gelang durch intensives Zerreiben in der Reibschale unter Zugabe von feinem Quarzsand, wobei die erzielten Werte auch bei verschieden langer Einwirkung der Verdauungsflüssigkeit und verschiedener Konzentration derselben immer konstant blieben. Nunmehr zeigte es sich allerdings, daß die so ermittelten Mengen an pepsin‐HCl‐unlöslichem N im Kot wesentlich niedriger waren als im Futter. Diese Differenzen scheinen jedoch bei Tieren derselben Art und bei einheitlichem Futter immer gleich hoch zu sein, so daß also die Möglichkeit bestände, nach Ermittlung dieser gleichbleibenden Abweichung mit Hilfe der Quantität an unlöslichem N im Kot auch diejenige im Futter festzustellen, wonach also das gewunschte Ziel auf einem unbedeutenden Umwege doch noch zu erreichen wäre. Wir fanden bei unseren im Stall gehaltenen Ochsen, daß die Menge im Kot nur noch 74,3% von derjenigen im Futter betrug. Nachdem wir nun auch bei den Weidetieren die im Kot gefundenen Werte entsprechend umrechneten, um diejenigen im Futter zu erhalten und die Errechnung der Futtermenge hiernach vornahmen, zeigte sich tatsächlich, daß die erhaltenen Resultate mit den nach der ersten Methode erzielten gut übereinstimmen.
Abgekürzte Kochdauer bei der Bestimmung der Rohfaser nach dem Weender‐Verfahren
Authors: Lepper W.
Published: August 2010

In Anlehnung an die früher veröffentlichte Zusammenstellung über die Arbeitsweise bei der Bestimmung der Rohfaser nach dem Weender‐Verfahren wird eine Abänderung in bezug auf die Kochdauer beschrieben.

Erforderlich ist eine Konzentration der Säure und Lauge von 3,125%, die Kochdauer beträgt dann nur je 10 Minuten.
Fütterungsversuche an Milchkühen zur Steigerung des Jodgehaltes der Milch durch Jodzulagen
Authors: Gabele A. , Schmittmann E.
Published: August 2010

Die vermehrte Jodzufuhr über die Milch zur Kropfverhütung bietet den großen Vorteil, daß dadurch organisch gebundenes Jod zusammen mit Vitamin A der kropfgefährdeten Bevölkerung zugeführt wird. Das Tier fängt evtl. auftretende Jodüberangebote ab und wirkt so als Puffer.

Um die Wirkung der Jodbeifütterung zu prüfen, wurden an zwei Milchkühen zwei Stoffwechselversuche durchgeführt. Im ersten Versuch wurden dem normalen Winterfutter in 10 ml KJ‐Lösung 15 mg Jod zugeführt. Im zweiten wurden dem Futter 19 g Tangmehl mit rund 5 mg Jod zugesetzt.

Die im Liter Milch ausgeschiedenen Jodmengen schwankten zwischen 98 und 250 mcg und lagen im Mittel bei etwa 130 mcg.

Hinsichtlich des Vitamin‐A‐Stoffwechsels war durch höhere Carotingaben keine Steigerung des Carotin‐ bzw. Vitamin‐A‐Anteils in der Milch zu beobachten, wie ein Vergleich der Versuche I und II zeigt.

Ein Sinken des Fettgehalts der Milch durch zusätzliche Jodgaben konnte bei der Zufuhr von 19 bzw. 9 mg Jod je Tier und Tag nicht beobachtet werden. Auch sonst waren keine nachteiligen Folgen der Jodbeifütterung an den Versuchstieren festzustellen.

Das Absinken der Milchmenge dürfte durch Störungen des Wohlbefindens durch die Stoffwechselgeschirre hervorgerufen sein. Deutlich geht aus den Versuchen hervor, daß Tangmehl gut geeignet ist, den Jodgehalt der Milch zu erhöhen.
Zur röntgenographischen Technik bei der biologischen Vitamin D‐Bestimmung mit Ratten
Authors: Brune H.
Published: August 2010

Röntgenbildveränderungen der Synchondrosis epiphyseos tibiae von rachitischen Ratten durch Positionsänderung der Tibia zum Röntgenfllm wurden untersucht. Praktische Hinweise für reproduzierbare Positionen der Tibia zum Röntgenfilm bei der lebenden Ratte werden gegeben.
Differenzierung von Qualitätsmerkmalen der Muskulatur des Schweines durch Quellungsversuche
Authors: Brune H. , Seika E.
Published: August 2010

Am Göttinger Schlachthof wurden von 140 Schweinen (Lebendgewicht um 100 kg) der veredelten Landschweinrasse beiderlei Geschlechts aus dem Musculus glutaeus superficialis unmittelbar post mortem Proben entnommen. Die Muskelproben wurden nach Druckfestigkeit und Farbe, wie bei der praktischen Fleischbeurteilung üblich, in zwei extreme Typen: Typ D = druckfest und dunkel, Typ H = nicht druckfest und hell, eingeteilt.

Die Gewichtsveränderung dieser Proben (ca. 2 g) nach dem Einlegen in Aqua dest. oder hypertonische Kochsalzlösungen unter Erneuerung dieser Lösungen alle zwei Stunden zeigte ein unterschiedliches Verhalten der extremen Muskeltypen an.

In hypertonischen Kochsalzlösungen erfolgte allgemein während der zehnstündigen Versuchsdauer eine differente Gewichtszunahme.

Signifikante Unterschiede der Gewichtsveränderung der Muskeltypen D und H ergaben sich bei der Behandlung mit Aqua dest. Dabei nahm der Muskeltyp D ständig an Gewicht zu (Quellung); der Muskeltyp H ständig an Gewicht ab (Entquellung). Die Erfassung des Austrittes stickstoffhaltiger Substanzen aus den Muskelproben kennzeichnete diese Muskeltypen ebenfalls als different.

Die Erfassung der Gewichtsveränderung der Muskelproben in Aqua dest. kann in übereinstimmung mit den praktischen Erfahrungen des Schlachters zur objektiven Kennzeichnung der Fleischqualität beitragen.
Die Nebenschilddrüsen und ihre Beziehungen zu innersekretorischen Drüsen und Organsystemen innerhalb des Mineralstoffwechsels1
Authors: Eger W.
Published: August 2010

Die Epithelkörperchen nehmen innerhalb des innersekretorischen Systems eine weitgehend unabhängige Stellung ein. Ein parathyreotropes Hormon gibt es nicht. Ebenso besteht keine direkte Beziehung zu einer anderen innersekretorischen Drüse. Allein mit den Nebennieren sind die Epithelkörperchen dadurch enger verknüpft, daß beide Drüsen den Mineralstoffwechsel beeinflussen und sich das Wirkungsgebiet beider Drüsen dadurch überschneidet.

Von Beziehungen der Epithelkörperchen zu Organen sind nur solche zu den Nieren bekannt, diese Beziehungen aber von besonderer Bedeutung. änderungen der Kalzium‐ und Phosphorausscheidung im Urin haben wiederum Rückwirkungen auf den Kalzium‐ und Phosphorgehalt des Blutes und damit auf die Funktion der Epithelkörperchen zur Folge. Es bleibt umstritten, ob die Höhe des Kalziumspiegels im Blut oder der Phosphorspiegel den adäquaten Reiz für die Funktion der Epithelkörperchen darstellt, oder ob umgekehrt die Epithelkörperchen primär die Phosphatausscheidung durch die Niere oder die Kalziummobilisation im Skelett und Gewebe beeinflussen. Beide Ansichten werden nach den heutigen Kenntnissen vertreten und bestehen zu Recht. Die Wirkung des Parathormons auf die Niere und das Skelettsystem dürfte eine unmittelbare sein.

Für die Regelung des Kalzium‐ und Phosphorstoffwechsels und den regelrechten Aufbau des Knochens ist neben dem Parathormon das Vitamin D in physiologischen Mengen notwendig. Beide Stoffe greifen unabhängig voneinander in den Stoffwechsel und das Knochensystem ein und können bei pathologisch überschüssiger Wirkung sich gegenseitig kompensieren. Vitamin D hemmt die Funktion der Epithelkörperchen, während Vitamin A sie anregt.

Es gibt bisher keine sicheren Anhaltspunkte dafür, daß die Epithelkörperchen mehrere Wirkstoffe produzieren.
Versuche mit Weißbrot und Weizenvollkornbrot bei Schweinen
Authors: Homb Thor , Husby Magnus , Breirem Knut
Published: August 2010

Es wurden hier die Ergebnisse von einem Versuch erklärt, in dem 2 Schweine Brot aus feinem Weizenmehl (Weißbrot) und 2 Schweine Brot aus 95% vermahlenem Weizenmehl (Vollkornbrot) erhielten. Das übrige Futter bestand aus Magermilch, etwas Kalksteinmehl und Tran. Mit derselben Trockensubstanzmenge im Futter war der Zuwachs je Tier 564 g je Tag bei den Weißbrotschweinen und 537 g je Tag bei den Vollkornbrotschweinen. Die mit Weißbrot gefütterten Schweine schieden nur ca. 40 g Kot pro Tag aus, während die Vollkornbrotschweine tägliche Kotmengen von 700 g hatten. Die Weißbrotschweine hatten harten, knolligen Kot mit hohem Trockensubstanzgehalt und waren etwas durch Verstopfung geplagt. Ein Zuschuß von fein zerkleinerter Zellulose zu der Weißbrotration gab bedeutend größere Kotmengen normaler Konsistenz.

Es bestand ein signifikanter Unterschied in der Verdaulichkeit der zwei Rationen zugunsten der Weißbrotration. Ansonsten zeigt der Versuch, daß Schweine normal wachsen und einen sehr günstigen Futterverbrauch je kg Zuwachs haben können, selbst wenn der Rohfasergehalt in der Trockensubstanz nur 1,5% beträgt.
Beiträge zur Aminosäurebestimmung in biologischem Material.
Authors: Müller R. , Krampitz G.
Published: August 2010

In Anbetracht der nach wie vor bestehenden Schwierigkeiten bei der quantitativen Bestimmung der Aminosäuren wird auf die in Deutschland wenig angewandte Chromatographie an Ionenaustauschersäulen hingewiesen.
Der Anteil tierischen Eiweißes im Kükenaufzuchtfutter und sein Ersatz durch pflanzliches Eiweiß bei Zugabe von antibiotischen Mitteln
Authors: Hohls H. W.
Published: August 2010

An Hand von 84 Kükenaufzuchtversuchen wird festgestelh, daß der Anteil tierischen Eiweißes auf 5% gesenkt werden kann, ohne daß eine merkliche Verschlechterung der Rohverwertung eintritt. Bei der Zugabe von Antibioticis läßt sich der Anteil tierischen Eiweißes auf minimal etwa 2% herabdrücken.

Der finanzielle Erfolg einer Geflügelmast hängt außer von den Daten für die Rohverwertung auch noch von den festen Kosten und den Arbeitslöhnen je kg erzeugten Gewichtes ab. Urn diese letzteren Faktoren einer späteren Berücksichtigung zugänglich zu machen, sind die zu erzielenden Tiergewichte bei den verschiedenen Anteilen tierischen Eiweißes angegeben worden.
Beitrag zur Durchführung von Verdauungsversuchen bei Schweinen mit Hilfe der Indikatormethode
Authors: Schneider W.
Published: August 2010

Zwei Versuche zur überprüfung der Brauchbarkeit der Indikatormethode mit Chromoxyd bei Verdauungsversuchen mit Schweinen brachten unterschiedliche Ergebnisse. Während im 1. Versuch bei quantitativer Kotsammlung eine sehr gute übereinstimmung zur üblichen Methode erzielt wurde, befriedigte sie im 2. Versuch bei Verwendung von wahllos gezogenen Proben nicht. Die Versuche werden fortgesetzt.
Langfristige Untersuchungen zum äußeren und inneren Stoffwechsel des graviden und laktierenden Schweines.
Authors: Lenkeit W. , Gütte J. O. , Warnecke W. , Kirchhoff W.
Published: August 2010

Zwei veredelte Landschweinsauen standen bei reichlicher Eiweißernährung während der ganzen Gravidität im Stoffwechselversuch. Die während der gesamten Gravidität retinierte N‐Menge überstieg die mit der Geburt abgegebenen N‐Mengen um 976 g N (Versuch Sie. I) bzw. um 1538 g N (Versuch Rap. II). Von diesen N‐Mengen sind im entleerten Uterus mit Adnexen nach Schlachtversuchen von Mitchell ca. 60 bis 65 g N enthalten, im Gesäuge nach früheren Analysen von Lenkeit ca. 80 bis 100 g N.

Beide Tiere blieben auch nach der Geburt im Stoffwechselversuch. Das eine Tier säugte 12 Ferkel (Versuch Rap. II) und verlor in 59 Laktationstagen 1162 g Körper‐N. Das zweite Tier wurde nach dem Abferkeln nicht besäugt (Versuch Sie. I) und verlor in 35 Tagen 647 g Körper‐N.

Die Versuche bestätigen frühere Vermutungen, daß der gravide Organismus des Schweines befähigt ist, bei reichlicher Eiweißernährung größere N‐Mengen über die Einlagerung in das Konzeptionsprodukt hinaus zu retinieren (“N‐Super‐Retention”), und daß nach dem Abferkeln ein großer Teil dieser N‐Mengen wieder abgegeben wird, und zwar auch dann, wenn eine Milchbildung nicht stattfindet (“negative überschuß‐Bilanz”). Darüber hinaus kann auch unzureichende Ernährung eine negative Bilanz (“Mangel‐Bilanz”) herbeiführen.
Zur Lokalisation des bakteriellen Oxalatabbaues im Verdauungstrakt von Kälbern mit Hilfe des Schlundrinnenreflexes
Authors: Brune H.
Published: August 2010

Calciumoxalat, das an drei Monate alte Kalber nur mit der Saugflasdie bei alleiniger Milchfütterung oder neben Heu und Kraftfutter verabreicht wurde, wurde mit dem Kot zu mehr als 93 % der aufgenommenen Menge ausgeschieden.

Nach Verabreichung von Calciumoxalat mit Trockenfutter wurden nur 75 % des verzehrten Oxalates ausgeschieden.

Es wird abgeleitet, daß der Pansen der Hauptort des Verdauungskanals für den mikrobiellen Oxalatabbau ist.