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Basiuk V A - - 2001
The problem of homochirality is of crucial importance for the origins of Life. While most laboratory studies are focused on the search of physical and chemical sources of handedness in the Universe, they reflect only one aspect of the problem: the origin of homochiral biomolecules. At the same time, any ...
Watanabe K - - 2001
Recent computation analyses have pointed out an existence of conserved amino acid motifs among RNA ribose 2'-O-methyltransferases. However, the functions of these motifs are unclear yet. We carried out the site-directed mutagenesis studies systematically on Thermus thermophilus HB8 tRNA (Gm18) methyltransferase gene. Subsequent biochemical analyses with purified variant enzymes clearly ...
Casimir J R - - 2000
A series of conformationally restricted analogs of the hen egg lysozyme (HEL) decapeptide 52-61 in which the conformationally flexible Tyr53 residue was replaced by several more constrained tyrosine and phenylalanine analogs was prepared. Among these tyrosine and phenylalanine analogs were 1,2,3,4-tetrahydro-7-hydroxyisoquinoline-3-carboxylic acid (Htc), 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic), 4-amino- 1,2,4,5-tetrahydro-8-hydroxy-2-benzazepine-3-one (Hba), 4-amino-1,2,4,5-tetrahydro-2-benzazepine-3-one ...
Singh U P - - 2000
The title molecule, C(15)H(23)N(3)O(5)S, was prepared as a synthetic precursor to 4-methylthiazole-based DNA minor groove binders which would bear chiral amino acids in the sequence. The crystallographic evidence presented herein shows that the aromatic amide NH group preceding the thiazole ring points away from the direction of sulfur. The molecule ...
Gregoriadis G - - 2000
Naturally occurring polymers of N-acetylneuraminic acid (polysialic acids) are biodegradable, highly hydrophilic and have no known receptors in the body. Following intravenous injection, polysialic acids exhibit long half-lives in the blood circulation and have therefore been proposed as carriers of short-lived drugs and small peptides. In addition, shorter-chain polysialic acids ...
Viedma C - - 2000
Formation of peptide bonds was attempted by thermal activation of dry amino acids from aqueous solution that simulated prebiotic evaporative environments. The evaporation trend of amino acids solutions shows a bifurcation and can lead to either a crystalline phase (near equilibrium) or a metastable non-crystalline phase (far from equilibrium). Only ...
Hess A - - 2000
For the recognition of all but the simplest naturally occurring molecules, electrochemical sensors based on ferrocene will certainly require chiral centers. To advance the necessary chemistry, this work describes the synthesis and properties of ferrocene derivatives of enantiomerically pure amino acids, peptides, and other chiral amines. Ferrocene aldehyde is condensed ...
Müller N - - 2000
The available methods for assaying of protease activity of unknown or partially defined specificity utilize long peptides, mostly denatured proteins, comprehending at least all coded amino acids in cleavable positions. In contrast, here we report on an alternative approach which utilizes a small synthetic ester substrate containing only one amino ...
Bui C T - - 2000
A replacement of the acetic acid moiety by valeric acid within the 4-hydroxymethylphenoxyacetic acid (HMP) linker (Sheppard RC, Williams BJ. Acid-labile resin linkage agents for use in solid phase peptide synthesis. Int. J. Peptide Protein Res. 1982; 20: 451-454) significantly improved its performance in terms of loading capacity, yield and ...
Malkinson J P - - 2000
The solid-phase synthesis of glycopeptides containing the sugar at the C-terminus is reported. The method is demonstrated on a model, the endogenous antinociceptive peptide Leu-enkephalin. 2,3,4-Tri-O-acetyl-1-azido-1-deoxy-beta-D-glucopyranuronic acid was synthesized and immobilized onto a variety of derivatized resins. Conjugation of the first amino acid was accomplished by reaction of the resin-bound ...
Berge J M - - 2000
Synthetic analogues of the microbial metabolite SB-219383 have been synthesised with defined stereochemistry. Densely functionalised hydroxylamine containing amino acids were prepared by the addition of a glycine anion equivalent to sugar-derived cyclic nitrones. One of four stereoisomeric dipeptides incorporating these novel amino acids was found to be a potent and ...
Hendrickson T L - - 2000
Some aminoacyl-tRNA synthetases have two catalytic centers that together achieve fine-structure discrimination of closely similar amino acids. The role of tRNA is to stimulate translocation of a misactivated amino acid from the active site to the editing site where the misactivated substrate is eliminated by hydrolysis. Using isoleucyl-tRNA synthetase as ...
Donkor I O - - 2000
2,3-Methanoamino acids are useful probes for studying the bioactive conformation of peptides and for investigating the effect of local conformational constraints on the activity of peptidomimetics. We synthesized all four stereoisomers of Cbz-protected 2, 3-methanoleucine for incorporation into peptidomimetic inhibitors of calpain. While the synthesis of 2,3-methanoamino acids has been ...
Rozhavskaya-Arena M - - 2000
We have previously reported that a synthetic peptide amide corresponding to amino acid residues 116-130 of mouse leptin, LEP-(116-130), reduces body weight gain, food intake, and blood glucose levels in ob/ob and db/db mice. In the present study we show that the activity of LEP-(116-130) resides in a restricted sequence ...
Buck R T - - 2000
A different approach to the synthesis of dipeptides is described based on the formation of the NHCHR1CONH-CHR2CO bond by carbenoid N-H insertion, rather than the formation of the peptide bond itself. Thus decomposition of triethyl diazophosphonoacetate catalysed by rhodium(II) acetate in the presence of N-protected amino acid amides 8 gives ...
Bourel L - - 2000
The selective deprotection of Lys(Mtt)-containing peptidyl resins was successfully monitored by RP-HPLC using very short linear gradients. RP-HPLC analyses of the acidic filtrates also revealed the partial cleavage of the Trt groups and of the peptide-resin bond. The absorbance of the Mtt carbocation at 470 nm is only twice that ...
Sankaranarayanan R - - 2000
Accurate translation of the genetic code depends on the ability of aminoacyl-tRNA synthetases to distinguish between similar amino acids. In order to investigate the basis of amino acid recognition and to understand the role played by the zinc ion present in the active site of threonyl-tRNA synthetase, we have determined ...
Li P - - 2000
Cyclosporin O (1), an extensively N-methylated immunosuppressive cyclic undecapeptide isolated from Tolypocladium inflatum Gams, was synthesized in 20-23% overall yield via 4 + 7 segment condensation and cyclization by the combined utilization of novel thiazolium- and immonium-type peptide coupling reagents 2-bromo-3-ethyl-4-methyl thiazolium tetrafluoroborate (BEMT) and 5-(1H-benzotriazol-1-yloxy)-3,4-dihydro-1-methyl 2H-pyrrolium hexachloroantimonate (BDMP) as ...
Nomanbhoy T K - - 2000
Certain aminoacyl-tRNA synthetases have a second active site that destroys (by hydrolysis) errors of amino acid activation. For example, isoleucyl-tRNA synthetase misactivates valine (to produce valyl adenylate or Val-tRNA(Ile)) at its active site. The misactivated amino acid is then translocated to an editing site located >25 A away. The role ...
Nishizawa T - - 2000
The peptide synthetase gene operon, which consists of mcyA, mcyB, and mcyC, for the activation and incorporation of the five amino acid constituents of microcystin has been identified [T. Nishizawa et al. (1999) J. Biochem. 126, 520-529]. By sequencing an additional 34 kb of DNA from microcystin-producing Microcystis aeruginosa K-139, ...
Gosselin F - - 2000
A versatile and practical approach for synthesizing azabicyclo[X.Y.0]alkane amino acids of different ring sizes from a common diaminodicarboxylate precursor has been developed as a means for mimicking different peptide conformations. (2S,9S)-1-tert-Butyl 10-benzyl 5-oxo-2-[N-(PhF)amino] 9-[N-(BOC)amino]dec-4-enedioate (18) was first prepared in 83% yield by the Horner-Wadsworth-Emmons olefination of N-(PhF)aspartate beta-aldehyde 8 with ...
Qiu Y - - 2000
We rearrange the genetic code and present a table of codons. The chemical properties of the amino acids coded by codons, and the evolutionary trend of codons are well reflected in the order of this table, from which two rules can be drawn: (1) the polarity/non-polarity and hydrophilicity/hydrophobicity of amino ...
Gunner M R - - 2000
Asymmetry in packing the peptide amide dipole results in larger positive than negative regions in proteins of all folding motifs. The average side chain potential in 305 proteins is 109 +/- 30 mV (2. 5 +/- 0.7 kcal/mol/e). Because the backbone has zero net charge, the non-zero potential is unexpected. ...
Günther R - - 2000
We present a protease-based method for the coupling of non-coded and non-amino-acid-derived amines with carboxy components. The key feature of this approach is the combination of the substrate-mimetic strategy with the ability of the cysteine protease clostripain to accept a wide spectrum of amines. Firstly, we tested the use of ...
Espinoza E - - 2000
FMRFamide-like peptide (FLP) amino acid sequences have been collected and statistically analyzed. FLP amino acid composition as a function of position in the peptide is graphically presented for several major phyla. Results of total amino acid composition and frequencies of pairs of FLP amino acids have been computed and compared ...
Lehmann J - - 2000
New insights on the origin of the genetic code, based on the analysis of the physico-chemical properties of its molecular constituents (RNA and amino acids), are reported in this paper. We point out a symmetry in the genetic code table and show that it can be explained by the nature ...
Kress J - - 2000
The convergent synthesis of a new class of chiral dendrimers is described. Owing to their structural resemblance to depsipeptides they are called depsipeptide dendrimers. The ex-chiral pool synthesis starts from (R,R)-, (S,S)-, and meso-tartaric acid as branching units and dipeptides or tripeptides consisting of glycine, (L)-alanine, and (L)-leucine as chiral-spacer ...
Kanzaki H - - 2000
A bacterium, strain NM 5-3, isolated from soil exhibited the highest cyclo(Gly-Leu) (CGL)-hydrolyzing activity and was identified as Agrobacterium radiobacter. The reaction products from CGL were dipeptides (Leu-Gly and Gly-Leu) and amino acids (Leu and Gly). Inhibitors for the dipeptidase of this strain did not inhibit the hydrolysis of CGL ...
Bittner S - - 2000
Since peptide quinones possess great clinical potential in targeted chemotherapy, several series of novel N-quinonyl amino acids have been synthesized and their first products of reduction were studied by EPR spectroscopy. EPR spectra of the corresponding radical adducts were identified by computer simulation. The dependence between the splitting constants and ...
Young V R - - 2000
We have selectively reviewed various aspects of protein and amino acid metabolism and nutrition which we feel are relevant and important in any comprehensive consideration of proteins, peptides, and amino acids in enteral nutrition. These, together with various clinical aspects of the problem that we have not addressed, are covered ...
Sisido M - - 2000
Extension of biochemical functions has been attempted by introducing nonatural amino acids and artificial nucleic acid analogs. Nonnatural amino acids have been linked to tRNAs and the amino-acylated tRNAs were added to E. coli in vitro protein synthesizing system to produce nonnatural mutant proteins. The positions of the nonnatural amino ...
Patrick R L - - 2000
The primary means of communication between neurons in the mammalian central nervous system (CNS) is via release of chemical transmitters. Although the first transmitters to be discovered were the biogenic amines, such as acetylcholine and norepinephrine, involved in transmission in the autonomic nervous system, the contribution of other types of ...
Asano Y - - 2000
Mainly microorganisms but only a few higher organisms are presently known to express enzymes that hydrolyze peptides containing D-amino acids. These enzymes can be involved in proceedings at the bacterial cell wall, in either assembly or modification, and thus cause resistance to glycopeptide antibiotics, or mediate resistance against beta-lactam antibiotics. ...
Ryan M P - - 1999
Lacticin 3147 is a two-component bacteriocin produced by Lactococcus lactis subspecies lactis DPC3147. In order to further characterize the biochemical nature of the bacteriocin, both peptides were isolated which together are responsible for the antimicrobial activity. The first, LtnA1, is a 3,322 Da 30-amino acid peptide and the second component, ...
Farrow M A - - 1999
The high accuracy of the genetic code relies on the ability of tRNA synthetases to discriminate rigorously between closely similar amino acids. While the enzymes can detect differences between closely similar amino acids at an accuracy of about 1 part in 100-200, a finer discrimination requires the presence of the ...
Spetzler J C - - 1999
The non-codable amino acid O-amino-serine, Ams, has been prepared in both L- and D-forms as the orthogonally protected derivative, Fmoc-Ams(Boc)-OH (1 and 2). This new amino acid derivative is useful for chemoselective ligations. Under acidic conditions and in the presence of all other common amino acid functionalities, the oxyamine function ...
Jiménez-Montaño M A - - 1999
A model for the developmental pathway of the genetic code, grounded on group theory and the thermodynamics of codon-anticodon interaction is presented. At variance with previous models, it takes into account not only the optimization with respect to amino acid attributes but, also physicochemical constraints and initial conditions. A 'simple-first' ...
Toyo'oka T - - 1999
Seventeen DL-amino acids labeled with a fluorescent chiral labeling reagent, R(-)-4-(3-isothiocyanatopyrrolidin-1-yl)-7-(N, N-dimethylaminosulfonyl)-2,1,3-benzoxadiazole (R(-)-DBD-PyNCS), were separated by reversed-phase chromatography and detected fluorometrically at 550 nm (excitation at 460 nm). The reagent reacted with amino functional group in dl-amino acids under basic medium. The thiocarbamoyl derivatives were converted to thiohydantoin via thiazolinone ...
Westermann B - - 1999
Readily available by lipase-catalyzed kinetic resolution or from a chiral pool, beta-, gamma-, and delta-lactams can be used as peptide building blocks for the synthesis of C-glycosylated amino acids 1. By reaction with glycosyl dianions, metabolic stable glycosylated amino acids can be prepared diastereoselectively. Ac=acetyl; Bn=benzyl; Boc=tert-butoxycarbonyl; R=Et, Bn; R'=H, ...
Wagschal K - - 1999
We describe here a systematic investigation into the role of position a in the hydrophobic core of a model coiled-coil protein in determining coiled-coil stability and oligomerization state. We employed a model coiled coil that allowed the formation of an extended three-stranded trimeric oligomerization state for some of the analogs; ...
Egli A - - 1999
A new peptide labeling method that uses the organometallic aquaion [99mTc(H2O)3(CO)3]+ has been developed. METHODS: A selection of amino acids was labeled at different concentrations with the organometallic aquaion, and the labeling yield was determined by high-performance liquid chromatography. This investigation has shown histidine to be a very potent ligand, ...
Müller B - - 1999
To improve the assembly of backbone cyclic peptides, N-functionalized dipeptide building units were synthesized. The corresponding N-aminoalkyl or N-carboxyalkyl amino acids were formed by alkylation or reductive alkylation of amino acid benzyl or tert-butyl esters. In the case of N-aminoalkyl amino acid derivatives the aldehydes for reductive alkylation were obtained ...
Nomanbhoy T K - - 1999
Misactivation of amino acids by aminoacyl-tRNA synthetases can lead to significant errors in protein synthesis that are prevented by editing reactions. As an example, discrete sites in isoleucyl-tRNA synthetase for amino acid activation and editing are about 25 A apart. The details of how misactivated valine is translocated from one ...
Suwannachot Y - - 1999
The presence of some amino acids and dipeptides under the conditions of the salt-induced peptide formation reaction (aqueous solution at 85 degrees C, Cu(II) and NaCl) has been found to catalyze the formation of homopeptides of other amino acids, which are otherwise produced only in traces or not at all ...
Lee Y S - - 1999
Salmon calcitonin (sCT) was prepared in good yield and high purity by the condensation of Nalpha-Boc-cyclic decapeptide, Boc-C1SNLSTC7VLG-OH (1,7-disulfide), with protected docosapeptide (Psc)LSQE(OPse)LHK(Psc)LQTYPRTNTGSGTP-NH2 x 3TFA, followed by deprotection of Boc with trifluoroacetic acid and Psc/Pse with piperidine. The 2-(phenylsulfonyl)ethoxycarbonyl (Psc) and 2-(phenylsulfonyl)ethyl (Pse) protecting groups were recently developed. The two ...
Stanchev M - - 1999
2-(Pyrrolidinyl)thiazole-4-carboxylic acid 5d, 2-(1-aminoalkyl)thiazole-4-carboxamides and hydrazides 8, 10 have been synthesized using alanine, valine, and proline as educts. In addition oxazole amino acids derived from leucine 20a and alanine 20b and some peptides 13, 14, 16 containing the 5-ring heterocyclic backbone modifications have been prepared. The thiazole and oxazole containing ...
Sampson W R - - 1999
A comparative study has been undertaken between Hmb-protected amino acid and pseudoproline building block analogues for use in the solid phase synthesis of 'difficult' peptides. Both of these derivatives act by blocking inter- and intramolecular hydrogen bonding, which has been shown to be a major cause of poor synthesis/quality/efficiency. While ...
Masuda Y - - 1999
We have newly found that interleukin-2 (IL-2) increases mouse voluntary running 24 hours, but not 30 minutes, after the injection. We suspected that IL-2 induced a substance increasing the voluntary running for 24 hours after injection. Serum obtained from mice 24 hours after the IL-2 treatment was fractioned with the ...
Fotsch C - - 1999
On-resin macrocyclization via an SNAr reaction is employed in the synthesis of tocinoic acid analogs. Specifically, an N-terminal nitrofluorobenzene is attacked by a nucleophilic C-terminal sidechain. The remaining nitro group can be reduced and acylated. NMR is used to compare the conformation of the new macrocyclic peptides to tocinoic acid.
Anini Y - - 1999
Endocrine L-cells of the distal intestine synthesize both peptide YY (PYY) and proglucagon-derived peptides (PGDPs), whose release has been reported to be either parallel or selective. Here we compare the release mechanisms of PYY, glucagon-like peptide-1 (GLP-1), and oxyntomodulin-like immunoreactivity (OLI) in vivo. Anaesthetized rats were intraduodenally (ID) given either ...
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