Stabilizing unusual conformations in small peptides and glucopeptides using a hydroxylated cyclobutane amino acid

2009 ◽  
Vol 7 (14) ◽  
pp. 2885 ◽  
Author(s):  
Alberto Fernández-Tejada ◽  
Francisco Corzana ◽  
Jesús H. Busto ◽  
Alberto Avenoza ◽  
Jesús M. Peregrina
Keyword(s):  
Amino Acid ◽  
Small Peptides

scholarly journals The sequence of amino acids in insulin isolated from islet tissue of the cod (Gadus callarias)

1968 ◽  
Vol 110 (2) ◽  
pp. 289-296 ◽  
Author(s):  
K. B. M. Reid ◽  
P T Grant ◽  
A. Youngson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Sequences ◽  
Small Peptides ◽  
Islet Tissue ◽  
Complete Digestion ◽  
The Individual ◽  
Derivatives Of

1. S-Aminoethylcysteinyl derivatives of the A and B chains of cod insulin were prepared from the individual S-sulpho chains. 2. Studies on small peptides derived from the S-aminoethylated peptide chains by treatment with trypsin allowed the amino acid sequences in the region of the cysteinyl residues of the A and B peptide chains to be defined. 3. The six amide groups in cod insulin were located by complete digestion of small peptides from the A and B chains with aminopeptidase followed by amino acid analyses. 4. The results, together with previous studies on the oxidized A and B chains, define the sequences of the 51 amino acids that constitute cod insulin.

Amino Acid Composition of Fishery Products

1949 ◽  
Vol 7c (9) ◽  
pp. 513-521 ◽  
Author(s):  
Catherine P. Deas ◽  
H. L. A. Tarr
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Essential Amino Acids ◽  
Waste Materials ◽  
Small Peptides ◽  
Isoleucine Leucine ◽  
Fish Flesh ◽  
Microbiological Methods ◽  
Fishery Products ◽  
Muscle Myosin

Fish flesh and certain waste materials were hydrolysed by tryptic enzymes of fish pyloric caeca. Fractionation of the resulting hydrolysates showed that they contained largely peptone, sub-peptone and residual (small peptides and amino acids) nitrogen, and little or no protein or proteose nitrogen. Fish flesh, milts, roes, meal, stickwater and a muscle myosin preparation were extracted to remove the fat, then dried and hydrolysed with acid or alkali. The essential amino acids arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, valine, tryptophane and tyrosine were determined in these enzyme-, acid- and alkali-hydrolysed materials by microbiological methods. The results have been summarized.

Imprinting Effects of Proline Containing Dipeptides (Proline-Glycine, Proline-Leucine, Proline-Valine and Their Retro Variants) in Tetrahymena. Evolutionary Conclusions

1997 ◽  
Vol 17 (6) ◽  
pp. 537-542 ◽  
Author(s):  
G. Csaba ◽  
P. Kovács
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Peptide Binding ◽  
Fluorescein Isothiocyanate ◽  
Physiological Effects ◽  
Small Peptides ◽  
Binding Studies ◽  
Hormone Formation ◽  
Selection Of

Proline-glycine, proline-leucine and proline-valine dipeptides and their retro variants were used in the experiments to study the effects of pretreatment (imprinting) in Tetrahymena, by investigating fluorescein isothiocyanate (FITC)-conjugated peptide binding. The protozoan organism could differentiate between the proline-dipeptides containing different partner amino-acids and between the dipeptides having the amino acids in reversed positions. The effect of imprinting was positive or negative and this was dependent on the type of the partner amino acid and on its position. Pro-Gly and Pro-Leu induced positive imprinting (elevated FITC-dipeptide binding) and Pro-Val induced negative imprinting (decrease of FITC-peptide binding). There was positive imprinting induction in two cases for the retro FITC-peptide and in one case for the FITC-conjugate of the imprinter peptide itself. The highest positive imprinting (almost 60% increase) was induced by Pro-Gly for FITC-Gly-Pro. Considering earlier—chemotaxis—experiments, the results of the present—binding—studies run parallel with the physiological effects. The experiments call attention to the sharp differentiating ability of small peptides at a unicellular level, that could have some role in the selection of molecules for hormone formation, during evolution.

Purification, Characterization, Gene Cloning, Sequencing, and Overexpression of Aminopeptidase N from Streptococcus thermophilus A

1999 ◽  
Vol 65 (7) ◽  
pp. 3001-3007 ◽  
Author(s):  
Frederic Chavagnat ◽  
Michael G. Casey ◽  
Jacques Meyer
Keyword(s):  
Amino Acid ◽  
Gel Filtration ◽  
Streptococcus Thermophilus ◽  
Maximal Activity ◽  
Amino Acid Sequences ◽  
Amino Acid Residues ◽  
Small Peptides ◽  
T7 Promoter ◽  
Reading Frame ◽  
Endopeptidase Activity

ABSTRACT The general aminopeptidase PepN from Streptococcus thermophilus A was purified to protein homogeneity by hydroxyapatite, anion-exchange, and gel filtration chromatographies. The PepN enzyme was estimated to be a monomer of 95 kDa, with maximal activity on N-Lys–7-amino-4-methylcoumarin at pH 7 and 37°C. It was strongly inhibited by metal chelating agents, suggesting that it is a metallopeptidase. The activity was greatly restored by the bivalent cations Co2+, Zn2+, and Mn2+. Except for proline, glycine, and acidic amino acid residues, PepN has a broad specificity on the N-terminal amino acid of small peptides, but no significant endopeptidase activity has been detected. The N-terminal and short internal amino acid sequences of purified PepN were determined. By using synthetic primers and a battery of PCR techniques, the pepN gene was amplified, subcloned, and further sequenced, revealing an open reading frame of 2,541 nucleotides encoding a protein of 847 amino acids with a molecular weight of 96,252. Amino acid sequence analysis of thepepN gene translation product shows high homology with other PepN enzymes from lactic acid bacteria and exhibits the signature sequence of the zinc metallopeptidase family. The pepN gene was cloned in a T7 promoter-based expression plasmid and the 452-fold overproduced PepN enzyme was purified to homogeneity from the periplasmic extract of the host Escherichia coli strain. The overproduced enzyme showed the same catalytic characteristics as the wild-type enzyme.

Acyl and amino intermediates in penicillopepsin-catalysed reactions and activation by nonsubstrate peptides

1977 ◽  
Vol 55 (4) ◽  
pp. 286-294 ◽  
Author(s):  
Tusn. T. Wang ◽  
Theo Hofmann
Keyword(s):  
Amino Acid ◽  
Proteolytic Activity ◽  
Acyl Transfer ◽  
High Yield ◽  
Major Conclusion ◽  
Small Peptides ◽  
Trypsinogen Activation ◽  
The Third ◽  
Effects Of Ph ◽  
Relative Specificity

The action of penicillopepsin on a variety of small peptides was studied qualitatively and kinetically. With the substrate benzyloxycarbonyl-Phe-Leu, benzyloxycarbonyl-Tyr-Leu and acetyl-Phe-Tyr the formation of Leu-Leu from the first two and Tyr-Tyr from the third substrate was observed. These reactions presumably proceed via a covalent amino-intermediate in analogy to pig pepsin. However, with penicillopepsin the yields of transpeptidation are low. In contrast, transpeptidations via acyl transfer proceed in high yield with a variety of substrates. With Leu-Trp-Met both acyl and amino transfer occurs as shown by the formation of Leu-Leu and Met-Met; unlike with pig pepsin, however, no Leu-Leu-Leu or Met-Met-Met was observed. Nonsubstrate peptides activate the cleavage of small substrates. (The term 'cleavage' is used here to imply that the reaction is either a hydrolysis or a transpeptidation, or both. The term 'hydrolysis' will only be used for strictly hydrolytic reactions.) As with pig pepsin the activators increase predominantly the transpeptidation reaction and have only small effects on hydrolysis. The activators increase kcat but have no effect on Km. Studies of the cleavage of six different peptides show that at pH 4.7 Km is lower than at pH 3.4 while kcat is unaffected. As with pig pepsin activation by nonsubstrate peptides is greater at pH 4.7 than at pH 3.4. Benzyloxycarbonyl-Glu-Tyr which is an inhibitor of trypsinogen activation (Ki = 50 μM) is an activator for the cleavage of Leu-Tyr-NH2 (Ka = 500 μM). Pepstatin, an inhibitor of the proteolytic activity of acid proteases, also inhibits the action of penicillopepsin on Leu-Tyr-NH2.The major conclusion from these studies is that the action of penicillopepsin on small peptides is qualitatively similar to that of pig pepsin. Transpeptidation reactions of both the amino acid and the acyl transfer type have been observed. However, there are considerable differences in the effects of pH, and in relative specificity between the two enzymes.

scholarly journals Peptidase Activity of Amidinated Thrombin

1977 ◽  
Author(s):  
E.P. Kang
Keyword(s):  
Amino Acid ◽  
Catalytic Efficiency ◽  
Enzymic Activity ◽  
Peptidase Activity ◽  
Amino Acid Residues ◽  
Small Peptides ◽  
Human Thrombin ◽  
Small Change ◽  
Hydrolysis Of ◽  
Hydrolysis Activity

Human thrombin, free of plasminogen and plasmin, was treated with ethyl acetimidate hydrochloride in order to modify the lysyl residues of the protein. By monitoring the enzymic activity in the modification mixture, it was found that the reaction was completed in about one hour and the loss of activity of thrombin was proportional to the amount of modification. After the removal of the excess ethyl acetimidate, approximately 25% of the clotting activity and of the hydrolysis activity for small peptides remained. Amino acid analysis of this modified thrombin indicated about 80% of the lysyl residues had been modified with no apparent change of other amino acid residues. By studying the thrombolytic hydrolysis of Bz-phe-val-arg-pNA, the kcat of the amidinated thrombin was about 8% of the control while the KM Secreased to 0.056 μM from 0.098 μM. The modification of the lysyl residues of thrombin, therefore, has lowered the catalytic efficiency of the enzyme with a rather small change in binding affinity. This suggests that modification of lysyl residues in the neighborhood of the active site hinders the catalytic hydrolysis of the small peptides.

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