bluuebunny/crossref_metadata_2025 huggingface dataset:
Maillard Reaction Products as Encapsulants for Fish Oil Powders
Authors: Augustin Mary Ann , Sanguansri Luz , Bode Ortwin
Published: August 2010

The use of Maillard reaction products for encapsulation of fish oil was investigated. Fish oil was emulsified with heated aqueous mixtures comprising a protein source (Na caseinate, whey protein isolate, soy protein isolate, or skim milk powder) and carbohydrates (glucose, dried glucose syrup, oligosaccharide) and spray‐dried for the production of 50% oil powders. The extent of the Maillard reaction was monitored using L*, a*, b* values and absorbance at 465 nm. Encapsulation efficiency was gauged by measurement of solvent‐extractable fat and the oxidative stability of the fish oil powder, which was determined by assessment of headspace propanal after storage of powders at 35 °C for 4 wk. Increasing the heat treatment (60 °C to 100 °C for 30 to 90 min) of sodium caseinate‐glucose‐glucose syrup mixtures increased Maillard browning but did not change their encapsulation efficiency. The encapsulation efficiency of all heated sodium caseinate‐glucose‐glucose syrup mixtures was high, as indicated by the low solvent‐extractable fat in powder (<2% powder, w/w). However, increasing the severity of the heat treatment of the sodium caseinate‐glucose‐glucose syrup mixtures reduced the susceptibility of the fish oil powder to oxidation. The increased protection afforded to fish oil in powders by increasing the temperature‐time treatment of protein‐carbohydrate mixtures before emulsification and drying was observed irrespective of the protein (sodium caseinate, whey protein isolate, soy protein isolate, or skim milk powder) and carbohydrate (glucose, glucose/dried glucose syrup, or oligosaccharide/dried glucose syrup) sources used in the formulation. Maillard reaction products produced by heat treatment of aqueous protein‐carbohydrate mixtures were effective for protecting microencapsulated fish oil and other oils (evening primrose oil, milk fat) from oxidation.
Selectivity Aspects of Lipolysis of Milkfat (Butteroil) by Immobilized Pregastric Esterases from Kid Goats and Lambs
Authors: Hill Charles G. , Ghannouchi Jr. Souheil , Lopez‐Hernandez Arnoldo , Garcia Hugo S.
Published: August 2010

Pregastric esterases derived from the salivary tissues of kid goats and lambs were immobilized by physical adsorption in a continuous flow, hollow‐fiber reactor and subsequently used to hydrolyze anhydrous milkfat, thereby producing lipolyzed butteroils. These 2 esterases were used in separate trials conducted at temperatures of 40 °C, 45 °C, and 50 °C and pH values of 5.0, 6.0, and 7.0. High‐performance liquid chromatography (HPLC) was used to determine the relative proportions of the different fatty acid residues released as functions of the reactor space time for the indicated operating conditions. For both esterases, the rates of the lipolysis reactions were fastest at 40 °C and a pH of 6.0. The rates of release of the native individual fatty acid residues were modeled using expressions of the generalized Michaelis‐Menten form based on a ping pong bi bi mechanism. Nonlinear regression analyses indicated that for both esterases, the experimental data were consistent with the form of the ping pong bi bi mechanism for which the rate controlling step is deacylation of the enzyme.
Development of Molecular Typing Methods for Bacillus spp. and Paenibacillus spp. Isolated from Fluid Milk Products
Authors: Durak M. Zeki , Fromm Hazel I. , Huck Jason R. , Zadoks Ruth N. , Boor Kathryn J.
Published: August 2010

Bacillus spp. and related sporeformers are important food spoilage organisms. While use of molecular subtyping methods has provided important information on the ecology and transmission of foodborne pathogens, the lack of rapid, reliable, and affordable subtyping methods for Bacillus spp. has limited our ability to understand and control their transmission throughout the food chain. We used a previously described collection of Bacillus spp. and Paenibacillus spp. isolated from dairy products to develop a DNA sequencing‐based subtyping approach for these spoilage microorganisms. After optimization of polymerase chain reaction (PCR) parameters, primers targeting the rpoB housekeeping gene allowed for successful amplification in all isolates. rpoB sequencing allowed differentiation of 29 subtypes (that is, sequence types) among the 57 isolates characterized. Phylogenetic analyses of rpoB sequences revealed distinct monophyletic lineages that correlated with bacterial genera (Bacillus and Paenibacillus) as well as with species or species‐like assemblages within each genus. rpoB sequencing provided improved subtype discrimination over 16S rDNA sequencing; therefore, rpoB sequencing allows for both sensitive subtype discrimination as well as for species and genus identification. Analysis of subtypes isolated over time in dairy products revealed the presence of both persistent and transient bacterial subtypes, indicating that application of these methods can improve our understanding of the ecology of these spoilage organisms and can help in identification of bacterial niches that may contribute to the persistence of these spoilage organisms in food systems.
Sweetpotato (Ipomoea batatas L.) Leaf: Its Potential Effect on Human Health and Nutrition
Authors: Islam Shahidul
Published: August 2010

Previous experiments revealed that sweetpotato leaves contain a high content of polyphenolics, namely anthocyanins and phenolic acids, compared with the major commercial vegetables. Sweetpotato leaves contain at least 15 biologically active anthocyanins that have significant medicinal value for certain human diseases and may also be used as natural food colorants. The anthocyanins were acylated cyanidin and peonidin type. The phenolic acids were composed of caffeic acid (CA) and 5 kinds of caffeoylquinic acid derivatives, 3‐mono‐O‐caffeoylquinic acid (chlorogenic acid, ChA), 3,4‐di‐O‐caffeoylquinic acid (3,4‐diCQA), 3,5‐di‐O‐caffeoylquinic acid (3,5‐diCQA), 4,5‐di‐O‐caffeoylquinic acid (4,5‐diCQA), and 3,4,5‐tri‐O‐caffeoylquinic acid (3,4,5‐triCQA). These polyphenolics showed various kinds of physiological functions, radical scavenging activity, antimutagenic activity, anticancer, antidiabetes, and antibacterial activity in vitro or in vivo, which may be helpful for maintaining and promoting human health. The physiological function of caffeoylquinic acid (CQA) derivatives with the plural caffeoyl group is more effective than with a monocaffeoyl one. This review describes the nutritional composition and physiological functions of sweetpotato leaves when used as a vegetable, and as a resource for products with these functions.
Effects of Processing on the Quality of Preserved Quartered Artichokes Hearts
Authors: Guillén‐Ríaos Pedro , Burló Francisco , Martíanez‐Sánchez Francisco , Carbonell‐Barrachina ÁNgel A.
Published: August 2010

Different methods of processing preserved quartered artichoke hearts were studied. All methods involved blanching of the product and removal of bracts; however, the order of these 2 unitary operations was changed. The main objective was to compare the effects of the different manufacturing methods on the physico‐chemical and sensory characteristics of the artichoke hearts. The traditional method (1st blanching of the fresh artichokes and then removal of bracts) provided quartered artichoke hearts with the best chemical and sensorial properties during storage at room temperature (20 °C ± 2 °C): slight acid taste, high artichoke flavor, white‐yellowish color, and no presence of brown spots.
Development, Stability, and Sensory Testing of Microcapsules Containing Iron, Iodine, and Vitamin A for Use in Food Fortification
Authors: Wegmüller Rita , Zimmermann Michael B. , Bühr Viviane G. , Windhab Erich J. , Hurrell Richard F.
Published: August 2010

Iodine, vitamin A, and iron deficiencies are important public health problems in developing countries and often coexist in vulnerable groups, such as pregnant women and young children. Food fortification can be a sustainable, cost‐effective strategy to combat these deficiencies. In remote, rural areas of subsistence farming, salt may be 1 of few regularly purchased food items and is therefore likely to be a good food vehicle for fortification. However, fortification of salt is challenging due to the white color and highly reactive impurities, and added micronutrients often cause color changes. Encapsulation may prevent or reduce these reactions. Potassium io‐date, retinyl palmitate, and ferric pyrophosphate were microencapsulated in hydrogenated palm fat by spray cooling. The size and morphology of the sprayed microparticles and losses of iodine and vitamin A during spraying were analyzed. The microcapsules were added to local salt in Morocco. During storage for 6 mo, color change in the triple fortified salt (TFS) was acceptable, and iodine losses were approximately 20% comparable to the iodized salt (IS). Stability of retinyl palmitate was excellent, resulting in losses of only about 12% after 6 mo of storage. Sensory tests were performed with typical Moroccan dishes cooked with either TFS or IS by triangle testing. No sensory difference was detectable, and overall acceptability of the salt was good. Encapsulation by spray cooling produces highly stable microcapsules containing iodine, vitamin A, and iron for salt fortification in Africa. Such capsules may also be used to fortify other dry matrices (for example, sugar, flour).
Oestrogen, Progesterone and Serotonin Converge on GABAergic Neurones in the Monkey Hypothalamus
Authors: Mirkes S. J. , Bethea C. L.
Published: August 2010

There are dense populations of inhibitory GABA neurones in regions of the primate hypothalamus that have been implicated in the neuroendocrine control of prolactin and luteinizing hormone (LH) secretion. A subpopulation of GABA neurones that express nuclear oestrogen and progestin receptors reside in the arcuate and infundibular nuclei. We questioned whether oestrogen or progesterone regulate the expression of GAD67, the rate limiting enzyme in GABA synthesis, in these regions. Female monkeys were spayed and treated with placebo, oestrogen, progesterone or oestrogen plus progesterone for 28 days and GAD67 mRNA was examined with singlein situhybridization. In the arcuate nucleus, there was no change in GAD67 mRNA expression with hormone treatment. However, in the infundibular region, oestrogen alone and oestrogen plus progesterone significantly suppressed GAD67 mRNA expression compared to spayed controls. In addition, expression of serotonin (5‐HT)2Creceptor mRNA overlaps markedly with the expression of GAD67 mRNA in the same region. We tested the hypothesis that GABA neurones express 5‐HT2Creceptors using doublein situhybridization. The highest concentrations of double‐labelled cells were detected in the medial preoptic region, the arcuate nucleus and the infundibular region. The suprachiasmatic and ventromedial nuclei contained predominantly 5‐HT2CmRNA expressing cells. The nucleus of the diagonal band of Broca and the globus pallidus contained predominantly GAD67 mRNA expressing cells. The bed nucleus of the stria terminalis, the paraventricular and dorsomedial nuclei contained different ratios of single‐labelled cells. Together these data suggest (i) that oestrogen decreases expression of GAD67 mRNA in the infundibular region which could lead to decreased GABA synthesis, but addition of progesterone had no further effect and (ii) that GABA neurones in the same region also express mRNA for the stimulatory 5‐HT2Creceptor which could promote GABA release during serotonin input.
Stem Cells, Hormones and Pituitary Adenomas
Authors: Levy Andy
Published: August 2010

We still do not understand the pathogenesis of the majority of pituitary adenomas or why, once formed, their behaviour tends to be so benign. Understanding trophic activity in the normal pituitary may be the key. Despite the fact that changes in indices of cell division and programmed cell death that are too small to measure can produce highly significant fluxes in cell populations, little by little, the fascinating patterns of integrated responses of pituitary cells to hormonal stimuli are now being revealed.
DETERMINATION OF THE COMPLETE AMINO ACID SEQUENCE OF BOVINE NEUROPHYSIN II
Authors: Schlesinger David H. , Capra J. Donald , Walter Roderich
Published: August 2010

Bovine neurophysin II (BNP‐II), a major neurohypophyseal hormone‐binding protein in the cow, was isolated from acetone‐dried posterior pituitary powder by gel filtration, ion exchange chromatography and preparative disc electrophoresis. The single‐chain protein is composed of 97 amino acids, possesses a molecular weight of 10,029, and contains seven disulfide bonds. The fully S‐alkylated protein, S‐carboxamido‐[C]‐ methylcysteine BNP‐II ([C]BNP‐II), was subjected to 80 automated cycles of the Edman degradation with positive identification of every amino acid residue through 65 cycles and many identifications through 80 residues. [C]BNP‐II was digested with chymotrypsin and the peptides were isolated by gel filtration and purified by ion exchange chromatography. A 55‐amino acid C‐terminal chymotryptic peptide was sequenced through 46 residues by automated Edman degradations producing a 38‐amino acid overlap with the sequence of [C]BNP‐II. This established the sequences of the first 88 residues of the protein. A chymotryptic nonapeptide was sequenced from NH2‐ to COOH‐terminus by manual Edman degradations which established the sequence through residue 94. COOH‐terminal analysis of aminoethylated BNP‐II elucidated the tetrapeptide sequence and produced an overlap with the sequenced chymotryptic nonapeptide, completing the proposed amino acid sequence, which is supported by amino acid compositions of three other chymotryptic and two tryptic peptides.
SIDE REACTIONS IN PEPTIDE SYNTHESIS:
Authors: Bodanszky Miklos , Tolle John C.
Published: August 2010

Acylation of amino acid β‐naphthylamides with protected (Boc) amino acid‐isobutylcarbonic acid mixed anhydrides resulted in each case in the formation of some undesired by‐product: an isobutyloxycarbonylamino acid β‐naphthylamide. The amount of this second acylation product was particularly high, with the hindered amino acids valine and isoleucine as carboxyl‐components. The nature of the amino component had no major influence on the extent of this side reaction.
DESIGN AND SYNTHESIS OF POTENTIN VIVOANTAGONISTS OF OXYTOCIN
Authors: BANKOWSKI KRZYSZTOF , MANNING MAURICE , SETO JENNY , HALDAR JAYA , SAWYER WILBUR H.
Published: August 2010

We have previously shown that the substitution of 8‐ornithine and 2‐O‐methyltyrosine alone and in combination in [1‐deaminopenicillamine] oxytocin (dPOT) brought about enhancements in antagonistic potencies to responses to oxytocinin vivo. To explore the effects of these subtitutions in analogs of dPOT containing larger alkyl substitutents on the β carbon at position 1 and on the tyrosine residue at position two, the following six analogs were synthesized: [1‐(β‐mercapto‐β, β‐diethylpropionic acid), 8‐ornithine] vasotocin (1, dEt2OVT); [1‐β‐mercapto‐β, β‐cyclopentamethylenepropionic acid), 8‐ornithine] vasotocin [2, d(CH2)5OVT); [1‐β‐mercapto‐β, β‐diethylpropionic acid), 2‐O‐methyltyrosine, 8‐ornithine]vasotocin [3, dEt2Tyr(Me)OVT]; [1‐(β‐mercapto‐β, β‐diethylpropionic acid), 2‐O‐ethyltyrosine, 8‐ornithine] vasotocin [4, dEt2Tyr(Et)OVT]; [1‐β‐mercapto‐β', β‐cyclopentamethylenepropionic acid), 2‐O‐methyltyrosine, 8‐ornithine] vasotocin [5, d(CH2)5Tyr(Me)OVT]; [1‐β‐mercapto‐β, β‐cyclopentamethylenepropionic acid), 2‐O‐methyltyrosine, 8‐ornithine] vasotocin [6, d(CH2)5Tyr(Et)OVT].

The required protected intermediates were synthesized by a combination of solid‐phase synthesis and by individual 8 + 1 couplings in solution. All six analogs antagonize the actions of oxytocin on the rat uterus in the absence of Mg2+, in the presence of 0.5 mM Mg2+and in situ. They also antagonize milk ejection responses to oxytocin, and the vasopressor responses to arginine vasopressin, and all have very low antidiuretic activities. With pA2values of 7.35 ± 0.08 and 7.37 ± 0.17, respectively, compounds 3 and 5 are the two most potent in vivo antagonists of oxytocin reported to date.
CONFORMATIONAL CHARACTERIZATION OF CYCLOPENTAPEPTIDE, LVAL‐LPRO‐GLY‐LVAL‐GLY: A REPEATING ANALOGUE OF ELASTIN
Authors: KHALED M.A. , VENKATACHALAM C.M. , SUGANO H. , URRY D.W.
Published: August 2010

The cyclopentapeptide, ·L·Val1‐L· Pro2‐Gly3‐L· Val4‐Gly5, was synthesized and its conformational characterization was carried out using n.m.r. and theoretical energy calculations. The n.m.r. studies indicated the existence of a cis Val1‐Pro2 peptide bond in water and a very strong intramolecular H‐bond between the Val1 NH and Gly3 C=O groups. This H‐bond forms a β‐turn (type II) placing Val4 Gly5 residues within the turn. Two minimum energy conformations were derived, one of which agrees very well with the solution conformation.
Conformation of model, alanine and proline containing tetrapeptides in water
Authors: LISOWSKI MAREK , SIEMION IGNACY Z. , SOBCZYK KATARZYNA
Published: August 2010

CD spectra of model alanine and prolyl‐alanine tetrapeptides were measured at different pH values. An analysis of the spectra shows that proline in position 2 or 4 of a tetrapeptide favours folding of the peptide chain, and unfolding when it is in position 3. Changes in CD spectra evidence growing amounts of the β‐turn conformation upon increasing pH, independent of proline position in the peptide chain.
Enkephalin analogs: synthesis and properties of analogs with lipophilic or extended carboxyl‐terminus. Quantitative structure‐activity relationship of analogs modified in residue position 5
Authors: NÁDASDI LÁSZLÓ , YAMASHIRO DONALD , LI CHOH HAO , HUIDOBRO‐TORO PABLO
Published: August 2010

Four analogs of enkephalin (EK) have been synthesized by the solid‐phase method and their biological activities have also been investigated. All four analogs were less active than Met‐enkephalin (Met‐EK) as shown by relative potencies in the guinea pig ileum (GPI) assay: Met‐EK, 100; [Phe5]‐EK‐NH2, 59; [Trp5]‐EK‐NH2, 11; Met‐EK‐Cys(Cam)‐OH, 37; andN, N'‐bis(Met‐EK)‐cystine, 34. Two of the analogs were more potent than Met‐EK as shown by relative potencies in the mouse tail‐flick assay for analgesia: Met‐EK, 100; [Phe5]‐EK‐NH2, 1340; [Trp5]‐EK‐NH2, 1640. Quantitative structure‐activity relationship calculations were carried out for GPI potencies of analogs substituted in position 5. The calculation indicated that, in this position, the bulkiness had the main influence.
Synthesis of analogs and oligomers ofN‐(2‐aminoethyl)glycine and their gastrointestinal absorption in the rat
Authors: Heimer E.P. , Gallo‐Torres H.E. , Felix A.M. , Ahmad M. , LamBros T.J. , Scheidl F. , Meienhofer J.
Published: August 2010

The synthesis of a series of analogs and oligomers ofN‐(2‐aminoethyl)glycine (Aeg) are described. The gastrointestinal absorption of these compounds was determined after intragastric administration. Analogs of Aeg bearing a substituent at the amino or carboxyl functions were absorbed to a lesser extent than the parent compound. In contrast, the di‐ and tetra‐oligomers of Aeg were more rapidly absorbed. Total absorption of these compounds was observed within 2 h after intragastric administration.
Current contributions of peptide synthesis to studies on brain‐gut‐skin triangle peptides
Authors: YAJIMA HARUAKI , FUNAKOSHI SUSUMU , AKAJI KENICHI
Published: August 2010

The usefulness of a strong acid, such as MSA or TFMSA/TFA, as a deprotecting reagent in peptide synthesis was examined. By synthesizing several structurally related brain‐gut‐skin triangle peptides, a number of advantageous features of the thioanisole‐mediated deprotecting procedure were demonstrated. New amino acid derivatives, Arg(Mts), Trp(Mts) and Asp(OChp), were introduced to improve the synthetic methodology of complex peptides and the superior properties of Cys(Ad) were evaluated.
Mode of calcium binding to enkephalins
Authors: SIEMION I.Z. , JANKOWSKI A. , SOBCZYK K. , SZEWCZUK Z.
Published: August 2010

The mode of calcium and europium binding to (4′‐amino)‐Phe4, Leu5‐enkephalin in acetonitrile was investigated by the spectrofluorimetric method. It was found that both these cations evoke the 1:1 complex formation. The complexation is accompanied by an increase of the distance between the aromatic rings (Tyr1 and APhe4) in the peptide. The study of 1 H‐n.m.r. of the peptide in water in the presence of increasing amounts of Eu+3 allowed us to identify the cation complexation sites of the peptide as the Leu5‐carboxyl group and (probably) the APhe4 amide carbonyl group.
SMS 201–995, an octapeptide somatostatin analogue.
Authors: WYNANTS C. , van BINST G. , LOOSLI H.R.
Published: August 2010

The possible conformations of SMS 201–995, an active analogue of somastostatin, have been studied in dimethylsulfoxide solution by 500 MHz proton n.m.r. spectroscopy. The assignments have been made by use of 2D‐correlated methods to detect long‐range coupling connectivities in aromatic residues and between the α protons of consecutive residues. NOESY experiments enabled us to correlate amide and α protons of neighbouring amino acid residues, which indicate a less flexible situation than in water. Measurements of temperature coefficients of the amide protons, of NH‐CαH coupling constants and NOE effects are in favour of one predominant conformation with a β turn, of type II', involving amino acids Phe3to Thr6.
Chemical and biological characterization of the galactose binding lectins from Trichosanthes kirilowii root tubers
Authors: YEUNG H.W. , NG T.B. , WONG D.M. , WONG C.M. , LI W.W.
Published: August 2010

Three galactose binding isolectins have been isolated from Trichosanthes kirilowii root tubers. Two of the isolectins, TK‐I and TK‐II, are similar in many aspects including molecular weight, amino acid composition, NH2‐terminal amino acid residue, blood group and carbohydrate specificities, immunodiffusion and immunoelectrophoretic behavior, hemagglutinating and insulinomimetic activities, and in possessing subunits with different molecular weights. Compared to TK‐I and TK‐II, lectin TK‐III has a larger molecular weight, subunits with the same molecular weight, a single and distinctive NH2‐terminal amino acid residue, a different isoelectric point and lower hemagglutinating activity. The three lectins share common antigenic determinants in their structures. β‐Linked terminal oligosaccharides containing D‐galactose inhibit hemagglutination induced by the lectins with a higher potency than α‐linked oligosaccharides. The lectins are non‐mitogenic and did not inhibit the concanavalin‐A induced mitogenic response of lymphocytes.
13C n.m.r. study of the structure and the metal ion binding sites of neuropeptides composed of L‐Asp and L‐Glu
Authors: LANNOM H. K. , DILL K. , DENARIE M. , LACOMBE J. M. , PAVIA A. A.
Published: August 2010

13C NMR spectral data are presented for a variety of possible neurodipeptides composed of L‐Asp, Ac‐L‐Asp, and L‐Glu which contain α and β peptide linkages. The data for the various compounds are compared to the data presented for Ac‐Asp‐Glu, a known neuropeptide, in order to gain structural information about the related compounds. Indications are that for compounds 1 and 5, thecispeptide bond configuration exists due to the interaction of zwitterionic species. This interaction appears to be eliminated when the β peptide bonds are formed, as in the case of compounds 3 and 7. Spin‐lattice relaxation times were used to confirm the structures. Electron‐nuclear relaxation rates are also used to elucidate the metal ion binding sites of these species.
Solid phase synthesis of thymosin β9
Authors: CHANDRAMOULI N. , BHARGAVA K.K. , INCEFY G.S. , MODAK M.J. , MERRIFIELD R.B.
Published: August 2010

Thymosin β9, a 41 residue thymic polypeptide, has been synthesized by a solid phase method. A modification of the low HF method was used to deprotect and cleave the peptide from the resin. Thymosin β9 was then obtained in analytically pure form by a one‐step purification procedure in 32% yield. The activity of thymosin β9 in the terminal deoxynucleotidyl transferase assay was greater than calf thymus fraction 5, but comparable to thymosin β4. In contrast to thymosin α1, neither β4 nor β9 was active in the rosette inhibition assay.
Isolation and characterization of an abortifacient protein, momorcochin, from root tubers of Momordica cochinchinensis (Family Cucurbitaceae)
Authors: YEUNG H.W. , NG T.B. , WONG N.S. , LI W.W.
Published: August 2010

A glycoprotein with a molecular weight of 32 000 as estimated by SDS‐polyacrylamide gel electrophoresis, and characterized by an abundance of Asp and Glu residues and an absence of Cys residues in its amino acid analysis, was isolated from fresh root tubers of Momordica cochinchinensis using a procedure that involved acetone precipitation, ammonium sulfate precipitation, ion exchange chromatography on DEAE Sepharose CL‐6B and gel filtration on Sephadex G‐75. The protein was capable of inducing mid‐term abortion in mice. The characteristics of this protein were compared and contrasted with those of the abortifacient proteins isolated from other plants of the Cucurbitaceae family.
Effect of calcium chloride on the conformation of proteins
Authors: BHAT R. , AHLUWALIA J.C.
Published: August 2010

Partial molar heat capacities (C°) and volumes (V°) for some amino acids and peptides were measured in 1 M aqueous calcium chloride solutions at ***298.15°K using a Picker flow microcalorimeter and an oscillating‐tube digital density mater. Using the data for these amino acids and peptides in water, the corresponding partial *** capacities of transfer (C°) and volumes (V°) from water to 1 M aqueous calcium chloride were deduced. These thermodynamic parameters are significantly positive, indicating that strong interactions occur between the ions of calcium chloride and the charged centres of these amino acids and peptides. A comparison has been made with a similar transfer of these compounds to sodium chloride solutions. The thermodynamic parameters of the transfer of peptide group (‐CONH) are much more positive in calcium chloride than in sodium chloride solutions. The implication of this result for the ability of calcium chloride to act as a stronger destabilizer of protein conformation is discussed.
Isopropyl chloroformate as a superior reagent for mixed anhydride generation and couplings in peptide synthesis
Authors: BENOITON N. LEO , LEE YOUNG , CHEN FRANCIS M.F.
Published: August 2010

Mixed anhydrides of N‐tert.‐butoxycarbonyl‐, N‐benzyloxycarbonyl‐ and N‐9‐fluorenylmethoxycarbonylamino acids were prepared using isopropyl chloroformate, and purified by edulcoration. They were more stable than the corresponding anhydrides obtained using ethyl and isobutyl chloroformates. Aminolysis of the anhydrides by an amino acid ester proceeded efficiently, the amount of urethane generated by reaction at the carbonate moiety being the same as that generated from the other anhydrides. Racemization attending the coupling of N‐benzyloxycarbonylglycylamino acids by the mixed anhydride method using isopropyl chloroformate was one third to one quarter of that observed for the same couplings using ethyl and isobutyl chloroformate.
Reconstitution of rapeseed high molecular weight protein from isolated subunits
Authors: BHUSHAN R. , MAHESH V.K. , MALLIKHARJUN P.V.
Published: August 2010

The high molecular weight protein was isolated from rapeseed and characterised. Six subunits were isolated in SDS (0.01%) solution on polyacrylamide gel electrophoresis and by gel filtration on Sephadex G‐100. Reassociation by removing SDS by co‐dialysis, against 10mM sodium phosphate buffer (pH 7.9) was done and the yield was about 90%. The reconstituted protein was indistinguishable from the intact protein in all respects. The subunits isolated from the native protein and the reconstituted protein were found to have identical molecular weights and N‐terminal amino acids. No disulphide bonds were observed in the subunit association. Amino acid analysis of the proteins and the six subunits was performed and the number of each amino acid residue calculated.
Unusual thionation of a cyclic hexapeptide
Authors: KESSLER HORST , GEYER ARMIN , MATTER HANS , KOCK MATTHIAS
Published: August 2010

One carbonyl oxygen of the cyclic hexapeptide cycle(‐Gly1‐Pro2‐Phe3‐Val4‐Phe5‐Phe6‐) (A) can be selectively exchanged with sulphur using Yokoyama's reagent. Surprisingly it was not the C=O of Gly1but that of Phe5which was substituted and cyclo(‐Gly1‐Pro62‐Phe3‐Va14‐Phe5ψ[CS‐NH]Phe6‐) (B)was obtained. Thionation results in a conformational change of the peptide backbone although the C=O of Phe5and the corresponding C=S are not involved in internal hydrogen bonds. Two isomers in slow exchange, containing a CIS Gly1‐Pro2bond in a βVIa‐turn (minor) and atransGly‐Pro bond in a βII′‐turn (major), were analyzed by restrained molecular dynamicsin vacuoand in DMSO as well as using time dependent distance constraints. It is impossible to fit all experimental data to a static structure of each isomer. Interpreting the conflicting NOES, local segment flexibility is found. MD simulations lead to a dynamic model for each structure with evidence of an equilibrium between a βI‐ and βII‐turn about the Val4‐Phe5amide bond in both thecisandtransisomers. Additionally proton relaxation rates in the rotating frame (R1p) were measured to verify the assumption of this fast βI/βII equilibrium within each isomer. Significant contributions to R1p‐rates from intramolecular motions were found for both isomers. Therefore it is possible to distinguish between at least four conformers interconverting on different time scales based on NMR data and MD refinement. This work shows that thionation is a useful modification of peptides for conformation‐activity investigations.
Affinity purification of a difficult‐sequence protein
Authors: BIANCHI ELISABETTA , SOLLAZZO MAURIZIO , TRAMONTANO ANNA , PESSI ANTONELLO
Published: August 2010

A biotinylated derivative of a designed, difficult‐sequence protein (the Minibody, Bianchi, E., Tramontano, A., Sollazzo, M. & Pessi, A. (1993) Int. J. Peptide Protein Res.41, 385–393) which represented only 3.7% of the crude, cleaved material was quantitatively recovered with about 70% purity, in a single step, by affinity chromatography on immobilised avidin. Purification to homogeneity was then easily achieved by preparative HPLC. This highly effective purification scheme must be contrasted with the previously shown multidimen‐ sional, low‐yield chromatographic protocol. Since no facilitation of the purification had been obtained by capping alone, this result suggests that capping is useful only in conjunction with affinity chromatography.
Solution conformations of the peptide backbone for DPDPE and its β‐MePhe4‐substituted analogs
Authors: NIKIFOROVICH G.V. , PRAKASH O.M. , GEHRIG CATHERINE A. , HRUBY VICTOR J.
Published: August 2010

The solution structures of DPDPE, a conformationally restricted pentapeptide with the sequence H‐Tyr1‐d‐Pen2‐Gly3‐Phe4‐d‐Pen5‐OH, and its four β‐MePhe4‐substituted analogs were examined by a combined approach including the NMR measurements in DMSO and water as well as independent energy calculations. It was concluded that several low energy conformers of DPDPE backbone satisfy the NMR data obtained in this study as well as in previous studies by other authors. These possible solution conformers of DPDPE in both DMSO and water share virtually the same type of cyclic backbone structure, with the Gly3residue in a conformation close to a γ‐turn, and the Phe4residue in a conformation close to α‐helical torsion angles. They differ in the space arrangements of the flexible Tyr1moiety. The solution structures of the β‐MePhe4‐substituted analogs of DPDPE are interesting. For analogs with anS‐configuration at the Cαatom in the Phe4residue, the cyclic backbone conformations resemble those of DPDPE itself, whereas for analogs with anR‐configuration at the Cαatom, the backbone conformation is somewhat different. This observation is in line with the high biological potencies and selectivities displayed by the former compounds but not by the latter ones. It was noted also that as far as the peptide backbone conformers are concerned, some of the possible DPDPE conformers in water are similar to the previously suggested model for the δ‐receptor‐bound conformation of DPDPE, becoming virtually identical to this conformation by rotating the side chains of the Tyr1and the Phe4residues.
Prediction of transmembrane helices from hydrophobic characteristics of proteins
Authors: PONNUSWAMY P.K. , GROMIHA M. MICHAEL
Published: August 2010

Membrane proteins, requiring to be embedded into the lipid bilayers, have evolved to have amino acid sequences that will fold with a hydrophobic surface in contact with the alkane chains of the lipids and polar surface in contact with the aqueous phases on both sides of the membrane and the polar head groups of the lipids. It is generally assumed that the characteristics of the aqueous parts of the membrane proteins are similar to those of normal globular proteins, and the embedded parts are highly hydrophobic. In our earlier works, we introduced the concept of ‘surrounding hydrophobicity’ and developed a hydrophobicity scale for the 20 amino acid residues, and applied it successfully to the study of the family of globular proteins. In this work we use the concept of surrounding hydrophobicity to indicate quantitatively how the aqueous parts of membrane proteins compare with the normal globular proteins, and how rich the embedded parts are in their hydrophobic activity. We then develop a surrounding hydrophobicity scale applicable to membrane proteins, by mixing judicially the surrounding hydrophobicities observed in the crystals of the membrane protein, photo synthetic reaction center from the bacterium Rhodopseudomonas viridis, porin from Rhodobacter capsulatus and a set of 64 globular proteins. A predictive scheme based on this scale predicts from amino acid sequence, transmembrane segments in PRC and randomly selected 26 membrane proteins to 80% level of accuracy. This is a much higher predictive power when compared to the existing popular methods. A new procedure to measure the amphipathicity of sequence segments is proposed, and it is used to characterize the transmembrane parts of the sample membrane proteins.
Peptide‐lanthanide interactions
Authors: APARNA K. , BALARAM P. , KRISHNAMURTHY S.S. , NETHAJ M.
Published: August 2010

Crystals of Eu‐(Gly‐Gly‐Gly) (H2O) 5.(ClO4) 3 are triclinic, spacegroup P with a=9.123 (2), b=11.185 (5), c=11.426 (2) Å; α=90.79 (2), β=98.08 (1), γ=98.57 (2)°; Z=2. The europium cation is surrounded by four oxygens from three different peptide units and four oxygens from water molecules. The geometry around the metal is a distorted bi‐capped trigonal prism. The peptide backbone conformation in this complex is compared with those in the free peptide and in various metal complexes. Considerable differences are observed between Eu(III) and Ca(II) complexes of triglycine.
Pegylated peptides II
Authors: LU YI‐AN , FELIX ARTHUR M.
Published: August 2010

General procedures are presented for the site‐specific pegylation of peptides at the NH2‐terminus, side‐chain positions (Lys or Asp/Glu) or COOH‐terminus using solid‐phase Fmoc/tBu methodologies. A model tridecapeptide fragment of interleukin‐2, IL‐2(44‐56)‐NH2, was chosen for this study since it possesses several trifunctional amino acids which serve as potential sites for pegylation. The pegylation reagents were designed to contain either Nle or Orn, which served as diagnostic amino acids for confirming the presence of 1 PEG unit per mole of peptide. NH2‐Terminal pegylation was carried out by coupling PEG‐CH2CO‐Nle‐OH to the free NH2‐terminus of the peptide‐resin. Side‐chain pegylation of Lys or Asp was achieved by one of two pathways. Direct side‐chain pegylation was accomplished by coupling with Fmoc‐Lys(PEG‐CH2CO‐Nle)‐OH or Fmoc‐Asp(Nle‐NH‐CH2CH2‐PEG)‐OH, followed by solid‐phase assemblage of the pegylated peptide‐resin and TFA cleavage. Alternatively, allylic protective groups were introducedviaFmoc‐Lys(Alloc)‐OH or Fmoc‐Asp(O‐Allyl)‐OH, and selectively removed by palladium‐catalyzed deprotection after assemblage of the peptide‐resin. Solid‐phase pegylation of the side‐chain of Lys or Asp was then carried out in the final stage with PEG‐CH2CO‐Nle‐OH or H‐Nle‐NH‐(CH2)2‐PEG, respectively. COOH‐Terminal pegylation was achieved through the initial attachment of Fmoc‐Orn(PEG‐CH2CO)‐OH to the solid support, followed by solid‐phase peptide synthesis using the Fmoc/tBu strategy. The pegylated peptides were purified by dialysis and preparative HPLC and were fully characterized by analytical HPLC, amino acid analysis,1H‐NMR spectroscopy and laser desorption mass spectrometry.
Polymethylene spacer linked bis(A1a) peptides form modified β:‐sheet structures
Authors: KARLE ISABELLA L. , RANGANATHAN DARSHAN
Published: August 2010

The adipoyl‐ and suberoyl‐linked bis(Ala) peptides have an extended backbone between the two Calpha; atoms in each molecule. They self‐assemble, through intermolecular hydrogen bonds and stacking of parallel strands, into highly ordered modified β‐sheet‐like structures. Crystal data for adipoyl bis(A1a)diester are as follows: C14H24N2)O6, monoclinic space group P21, a = 4.900(1), b = 29.093(10), c = 6.021(2) Å, β= 104.20(2)˚, R = 0.053 for 1100 data >3σ(F); for suberoyl bis(A1a)diester: C16H28N2O6, monoclinic space group P21, a = 4.887(2), b = 32.650(9), c = 6.004(2) Å; β= 103.79(3), R = 0.070 for 1065 data > 3σ.
Prediction of conformational states of amino acids using a Ramachandran plot
Authors: KOLASKAR A.S. , SAWANT SANGEETA
Published: August 2010

(φ, ψ) data from crystal structures of 221 proteins having high resolution and sequence similarity cut‐off at the 25% level were analysed by dividing the Ramachandran plot in three regions representing three conformational states: (i) conformational state 1: conformations in the (φ. ψ) range from (‐140°, ‐100°) to (0°, 0°); (ii) conformational state 2: conformations with (φ, ψ) from (‐180°, 80°) to (0°, 180°); and (iii) conformational state 3: all the remaining conformations in the (φ, ψ) plane which are not included in the above two conformational states.

Normalized probability values of the occurrence of single amino acid residues in conformational regions 1‐3 and similar values for dipeptides were calculated. Comparisons of single residue and dipeptide normalized probability values have shown that short‐range interactions, although strong, destabilize conformational states of only 44 dipeptides out of the 400 × 9 possible states. However, dipeptide frequency values provide better resolving power than single‐residue potentials when used to predict conformational states of residues in a protein from its primary structure. The simple approach used in the present study to predict conformational states yields an accuracy of >70%, for 14 proteins and an accuracy in the range of 50–700% for 247 proteins. Thus these studies point out yet another use of the Ramachandran plot and the role of tertiary interactions in protein folding. ©Munksgaard 1996.
Effect of aromatic amino acid substitutions in the 3‐position of cyclic β‐casomorphin analogues on μ‐opioid agonist/δ‐opioid antagonist properties*
Authors: SCHMIDT RALF , WILKES BRIAN C. , CHUNG NGA N. , LEMIEUX CAROLE , SCHILLER PETER W.
Published: August 2010

The β‐casomorphin‐5 analog H‐Tyr‐c[‐D‐Orn‐2‐Nal‐D‐Pro‐Gly‐] (2‐Nal = 2‐naphthylalanine) was the first reportedcyclicopioid peptide with mixed μ agonist/δ antagonist properties [R. Schmidtet al.(1994)J. Med. Chem.37, 1136‐1144]. The 2‐Na13residue in this peptide was replaced with benzothienylalanine (Bta) (3), His(Bz1) (4), Tyr(Bz1) (5), 4′‐benzoylphenylalanine (Bpa) (6), 4′‐benzylphenylalanine (Bzp) (7), thyrnine (Thy) (8), thyroxine (Thx) (9), 4′‐biphenylalanine (Bip) (10), 4′‐biphenylglycine (Bpg) (12) and 3,3‐diphenylalanine (Dip) (14), and thein vitroopioid activity profiles of the resulting compounds were determined in μ and δ receptor‐representative binding assays and bioassays. Analogues 3, 12 and 14 were full agonists in the μ receptor‐representative guinea‐pig ileum (GPI) assay and also were agonists in the δ receptor‐representative mouse vas deferens (MVD) assay. The agonist effects of the latter compounds in the MVD assay were antagonized by the highly selective δ antagonist H‐Tyr‐Tic‐Phe‐Phe‐OH (TIPP), indicating that they were triggered by δ receptor activation. The Bzp3‐ and Bip3‐containing peptides 7 and 10 turned out to be μ antagonists against the μ selective agonist H‐Tyr‐D‐Ala‐Phe‐Phe‐NH2, in the GPI assay. The other analogues were weak partial μ agonists which displayed remarkably decreased μ receptor affinity as compared to parent peptide 1. Compounds 4‐10 were found to be δ antagonists in the MVD assay. Analogues 4 and 9 exhibited δ antagonist potency similar to that of parent peptide 1, while compounds 5‐8 and 10 showed 3‐12‐fold higher δ antagonist potency against DPDPE and deltorphin I and, in most cases, increased δ receptor affinity. These results indicate that the & delta; receptor tolerates bulky aromatic side chains in the 3‐position of cyclic β‐casomorphin analogs with either δ agonist or δ antagonist properties. However, these compounds displayed drastically reduced μ receptor affinity in nearly all cases. © Munksgaard 1996.
Distinct conformational preferences of three cyclic β‐casomorphin‐5 analogs determined using NMR spectroscopy and theoretical analysis
Authors: CARPENTER KATHARINE A. , SCHILLER PETER W. , SCHMIDT RALF , WILKES BRIAN C.
Published: August 2010

The conformational properties of three cyclic β‐casomorphin analogs based on the general formula H‐Tyr‐c[‐D‐Orn‐2‐Nal‐D‐Pro‐Xaa‐] (2‐Nal = 2‐naphthylalanine; Xaa = D‐Ala, Sar or NMe‐Ala) in DMSO solution were investigated using NMR spectroscopy in conjunction with molecular modeling techniques. The D‐Ala5‐ and Sar5‐analogs (compounds 1 and 2, respectively) are potent mixed μ‐agonist/§‐antagonists with high μ‐ and §‐opioid receptor affinities, whereas the NMe‐Ala5‐analog (compound 3) is a potent μ‐agonist and a weak partial §‐agonist. Distinct conformational differences emerged for the three compounds studied. Flexibility in the bare ring structures was found to increase in the order 3<2<1. The increased structural rigidity of 3 may be responsible for its low §‐receptor affinity as compared to the two other analogs. A low fractional population of conformers containing twocispeptide bonds was found for compound 2 but not for analog 1 or 3. Initial evidence for this observation was obtained from NMR differential line‐broadening experiments and later confirmed by molecular mechanics simulations. Comparison of the temperature dependence of amide proton chemical shifts acquired for the three cyclic analogs indicate a large degree of intramolecular hydrogen bonding for 1 but not for the other two peptides. © Munksgaard 1996.
Untersuchungen über Veränderungen in Magermilchpulvern während der Lagerung
Authors: Richter K. , Schiller K.
Published: August 2010

Magermilchpulver, die auf drei verschiedene Arten (Walzenfeinschicht‐ [A], Aufsprüh‐[B] und Sprühdüsenverfahren [C]) hergestellt worden waren, und ein Kraftfutterge‐misch mit 50 % Magermilchpulver wurden in normaler (n) und in Sonderverpackung (s) ein Jahr lang in einem Futterspeicher unter praktischen Bedingungen gelagert. Alle 2 Monate wurden die biol. Wertigkeit, die wahre Verdaulichkeit sowie die Zunahme je g aufgenommenes Roh‐ bzw. verdauliches Eiweiß bei einem Eiweißanteil von 12 % in der Futtertrockensubstanz bestimmt. Den biologischen Untersuchungen parallel wurde die Verteilung der Stickstoffsubstanz chemisch untersucht. Die Ergebnisse kön‐nen wie folgt zusammengefaßt werden.

Magermilchpulver, das in Papiersäcken gelagert wurde, unterlag mit der Zeit einer starken Verhärtung in den Außenschichten. Cellophansäcke verzögern diesen Vorgang wesentlich.

Die Wasserlöslichkeit des Reineiweißes fiel unabhängig von der Verpackungsart. Bei dem nach dem Sprühverfahren getrockneten Pulver erhielt sich die hohe Löslichkeit bei Speicherlagerung am besten.

Die Eiweißverdaulichkeit veränderte sich im Laufe der Lagerung nicht signifikant.

Die biol. Wertigkeit des Eiweißes unterlag einer stetigen, in den Sommermonaten gesteigerten Abwertung. In einem Kraftfuttergemisch aus 50 % Magermilchpulver und Futtermitteln mit geringem Gehalt an reduzierenden Zuckern wurde die Umlagerung nicht erhöht.

Obwohl unter den in der Praxis herrschenden Verhältnissen mit einer Abnahme der biol. Eiweißwertigkeit von Magermilchpulver während der Lagerung gerechnet wer‐den muß, bleibt das in frischer Form sehr hochwertige Magermilchpulver auch nach einem Jahr Lagerung noch ein hochwertiges Eiweißfuttermittel, das in seiner Ei‐weißwirkung gutem Fischmehl gleich, wenn nicht überlegen ist. Nach den vorliegenden Erfahrungen ist kühle und trockene Lagerung in Sonderverpackung (Cellophansäcken) zu empfehlen.
Methoden zur Bestimmung der Körperzusammensetzung lebender Tiere unter besonderer Berücksichtigung des Schweines
Authors: Hörnicke H.
Published: August 2010

Die Berechnung des Körperbestandes an Fett, Eiweiß und Asche aus dem Körperwasser (GKW) oder der Körperdichte setzt eine Kenntnis der Zusammensetzung der fettfreien Körpersubstanz (FKS) voraus. Bei allen bisher untersuchten Tierarten nimmt der Wassergehalt der FKS während des Wachstums fortlaufend ab. Nach Abschluß der chemischen Reife erreicht die FKS aber eine nahezu konstante Zusammensetzung, so daß unter Verwendung von aus chemischen Ganzkörperanalysen gewonnenen Normalwerten Formeln zur Berechnung der Korperzusammensetzung auf GKW oder Dichte aufgestellt werden können.

Stehen zwei voneinander unabhängige Meßgrößen – wie GKW und extracellulares Wasser oder GKW und Dichte – zur Verfügung, dann wird die Berechnung unabhängig vom Wassergehalt der FKS. Damit kann auch eine Bestimmung der Korperzusammensetzung von wachsenden Organismen vorgenommen werden. Es ist dazu nur noch die Kenntnis des Wassergehaltes der Zellmasse oder des Aschegehaltes der fettfreien Trockensubstanz erforderlich. Diese Größen sind aber weitgehend unabhängig vom Alter der Individuen.

Die für Berechnungen dieser Art notwendigen Formeln werden angegeben.
Über die Beeinflussung der Vitamin‐B1‐Resorption durch Antibiotica
Authors: Gassmann B. , Ketz H.‐A. , Haenel H.
Published: August 2010

In 30 und 60 Tagen dauernden Fütterungsversuchen mit insgesamt 600, suboptimal mit Vitamin B1 versorgten wachsenden Albinoratten wird an der Erhöhung des Vitamin‐B1‐Gehaltes der Leber nachgewiesen, daß Futterzulagen von Oxytetracyclin (10, 100, 1000, 3000 ppm Terramycin), Knoblauch (1%) oder Zwiebellauch (1%>) eine bessere Verwertung des Nahrungsthiamins zur Folge haben. Aus Resorptionstests mit 35S‐Thiamin geht hervor, daß hierfür eine Erhöhung der Resorptionsquote im Dunndarm verantwortlich ist. Die Resorption aus dem Blind‐ und Dickdarm wird hingegen nicht in gleicher Weise gefördert.

Hinsichtlich des Oxytetracyclineinflusses auf die Dickdarmflora deuten sich gewisse Parallelen zum Menschen an: Abnahme der Lactobazillen‐, Zunahme der Coli‐und Proteuszahlen. Die Gesamtkeimzahl bleibt gleich.

Aus den Versuchsergebnissen wird geschlossen, daß die durch Oxytetracyclin be‐wirkte Hemmung des bakteriellen Stoffwechsels bestimmte morphologische Veränderungen sowie eine Verminderung des bakteriellen Thiaminverbrauches im Dünndarm zur Folge hat und dadurch eine bessere Ausnutzung des Nahrungsthiamins ermöglicht.