STUDIES ON THE ENZYMATIC DEGRADATION OF OXYTOCIN AND VASOPRESSIN BY HUMAN PREGNANCY SERA

1967 ◽  
Vol 54 (4) ◽  
pp. 618-628 ◽  
Author(s):  
A. M. Riad
Keyword(s):  
Paper Chromatography ◽  
Enzymatic Degradation ◽  
Peptide Bond ◽  
Cysteic Acid ◽  
Tyrosine Residue ◽  
Enzymatic Cleavage ◽  
Amino Terminal ◽  
Lysine Vasopressin ◽  
Synthetic Oxytocin ◽  
Residue Position

ABSTRACT The enzymatic cleavage of synthetic oxytocin and 8-lysine vasopressin by sera of women in advanced pregnancy was investigated by using paper chromatography. Following incubation of either hormone with pregnancy serum and subsequent oxidation, two molecular fractions were formed, of which one could be identified as L-cysteic acid. By contrast, oxidation of the intact cyclopeptide hormones did not lead to liberation of free L-cysteic acid. It was concluded that oxytocin and 8-lysine vasopressin were cleaved by an identical mechanism involving splitting of the peptide bond joining the tyrosine residue (position 2) to the amino-terminal halfcystine residue (position 1). Pregnancy serum »oxytocinase« and »vasopressinase« thus appeared to be one and the same enzyme.

Application of a sequence-specific radioimmunoassay for the carboxyl-terminal region of corticotropin.

1981 ◽  
Vol 27 (4) ◽  
pp. 549-552 ◽  
Author(s):  
L H Lazarus ◽  
R P DiAugustine ◽  
M N Khan ◽  
G D Jahnke ◽  
M D Erisman
Keyword(s):  
Molecular Mass ◽  
Human Plasma ◽  
Silicic Acid ◽  
Peptide Bond ◽  
Terminal Region ◽  
Carboxyl Terminus ◽  
Proteolytic Degradation ◽  
Amino Terminal ◽  
Specific Radioimmunoassay ◽  
Carboxyl Terminal

Abstract The carboxyl terminal region of corticotropin (ACTH), (Ala34-Phe-Pro-Glu-Leu-Phe39), a region of the hormone conserved during evolution, served as an antigen for the production of a sequence-specific antiserum. In a radioimmunoassay, peptides that extend toward the amino terminal from Ala34, such as [Tyr,Gly]-ACTH34-39, ACTH18-39, and ACTH, had greater affinity for the antibody, which suggests that the antiserum recognizes the peptide bond preceding the alanyl residue. The assay readily detects 30 to 50 pmol of ACTH per liter with an incubation of only 3 h, and the antiserum cross reacts with larger molecular mass forms of the hormone. The amount of immunoreactive ACTH extracted by adsorption onto silicic acid from rat and human plasma was only 0.36 to 0.79 of that detected by a mid-region ACTH assay, which suggests proteolytic degradation at the carboxyl terminus of ACTH.

scholarly journals Crucial Role of the Amino-Terminal Tyrosine Residue 42 and the Carboxyl-Terminal PEST Domain of IκBα in NF-κB Activation by an Oxidative Stress

2000 ◽  
Vol 164 (8) ◽  
pp. 4292-4300 ◽  
Author(s):  
Sonia Schoonbroodt ◽  
Valérie Ferreira ◽  
Martin Best-Belpomme ◽  
Johan R. Boelaert ◽  
Sylvie Legrand-Poels ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Crucial Role ◽  
Tyrosine Residue ◽  
Amino Terminal ◽  
Carboxyl Terminal

Free chymotrypsin-catalyzed synthesis of peptide bond in aliphatic alcohols with low water content

1989 ◽  
Vol 54 (1) ◽  
pp. 266-276 ◽  
Author(s):  
Václav Čeřovský ◽  
Karel Martinek
Keyword(s):  
Dimethyl Sulfoxide ◽  
Water Content ◽  
Maximum Yield ◽  
Peptide Bond ◽  
Aliphatic Alcohols ◽  
Amino Terminal ◽  
Effect Of Water ◽  
Reaction Proceeds ◽  
Hydrolysis Of ◽  
Lower Water Content

The effect of water content on free chymotrypsin-catalyzed reaction of Ac-Tyr-OEt with HBr.Gly-NH2 in triethylamine-containing 2-propanol was studied. Maximum yield of dipeptide Ac-Tyr-Gly-NH2 was obtained in 2-propanol with 2% of water. Lower water content retards the reaction. Although higher water content accellerates the process, the yield of the dipeptide is reduced by enzymatically catalyzed hydrolysis of Ac-Tyr-OEt. The studied reaction proceeds analogously also in other aliphatic alcohols woth low content of water except in methanol; it does not take place in dimethylformamide or dimethyl sulfoxide containing 2% or 20% of water. In 2-propanol with 2% or 5% of water, syntheses of the protected amino-terminal oxytocine and vasopressin tripeptide, as well as other model peptides, were studied. In all the described experiments, α-chymotrypsin without any stabilization or immobilization was employed.

scholarly journals IgA proteases of two distinct specificities are released by Neisseria meningitidis.

1980 ◽  
Vol 152 (5) ◽  
pp. 1442-1447 ◽  
Author(s):  
M H Mulks ◽  
A G Plaut ◽  
H A Feldman ◽  
B Frangione
Keyword(s):  
Amino Acid ◽  
Neisseria Meningitidis ◽  
Heavy Chain ◽  
Peptide Bond ◽  
Amino Acid Sequences ◽  
Hinge Region ◽  
Amino Terminal ◽  
Group A

Strains of Neisseria meningitidis produce two distinct extracellular IgA proteases that cleave the human IgA1 heavy chain at different points within the hinge region. Type 1 protease cleaves the prolyl-seryl peptide bond at position 237-238; type type 2 protease cleaves the prolyl-threonyl bond two residues amino terminal to that bond attacked by type 1 enzyme. Each meningococcal isolate elaborates only one of these two enzymes, and the type of protease produced correlates with certain serogroups: group A yielding only type 1, and groups X and Y only type 2 enzyme. In addition, analysis of amino acid sequences of human alpha-chain proteins reveals that the repeating octapeptide characteristic of the IgA1 hinge region is actually triplicated.

scholarly journals Haemoglobins of the Shark, Heterodontus Portusjacksoni II. Amino Acid Sequence of the a-Chain

1976 ◽  
Vol 29 (2) ◽  
pp. 73 ◽  
Author(s):  
AR Nash ◽  
WK Fisher ◽  
EOP Thompson
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Paper Chromatography ◽  
Cyanogen Bromide ◽  
Gel Filtration ◽  
Amino Acid Sequences ◽  
Tryptic Digestion ◽  
Amino Terminal ◽  
Core Peptide ◽  
A Chain

The amino acid sequence of the a-chain of the principal haemoglobin from the shark, H. portusjacksoni has been determined. The chain has 148 residues and is acetylated at the amino terminal. The soluble peptides obtained by tryptic and chymotryptic digestion of the protein or its cyanogen bromide fragments were isolated by gel filtration, paper ionophoresis and paper chromatography. The amino acid sequences were determined by the dansyl-Edman procedure. The insoluble 'core' peptide from the tryptic digestion contained 34 residues and required cleavage by several proteases before the sequence was established. Compared with human a-chain there are 88 amino acid differences including the additional seven residues which appear on the amino terminal of the shark chain. There is also one deletion and one insertion. The chain contains no tryptophan but has four cysteinyl residues which is the highest number of such residues recorded for a vertebrate globin.

scholarly journals YLMY Tyrosine Residue within the Cytoplasmic Tail of Newcastle Disease Virus Fusion Protein Regulates Its Surface Expression to Modulate Viral Budding and Pathogenicity

2021 ◽  
Vol 9 (3) ◽  
Author(s):  
Yawen Bu ◽  
Qingyuan Teng ◽  
Delan Feng ◽  
Lu Sun ◽  
Jia Xue ◽  
...  
Keyword(s):  
Cell Surface ◽  
Fusion Protein ◽  
Surface Expression ◽  
Protein Processing ◽  
Cell Surface Expression ◽  
Tyrosine Residue ◽  
F Protein ◽  
Tyrosine Residues ◽  
Amino Terminal ◽  
Viral Budding

The amino-terminal cytoplasmic domains of paramyxovirus fusion glycoproteins include trafficking signals that influence protein processing and cell surface expression. This study clarified that tyrosine residues at different positions in the YLMY motif in the cytoplasmic region of the F protein regulate F protein transportation, thereby affecting viral replication and pathogenicity.

125I-LABELLING OF ANGIOTENSIN I AND II

1971 ◽  
Vol 67 (1) ◽  
pp. 104-116 ◽  
Author(s):  
Meta Damkjær Nielsen ◽  
Mogens Jørgensen ◽  
Jørn Giese
Keyword(s):  
Angiotensin Ii ◽  
Paper Chromatography ◽  
Enzymatic Degradation ◽  
Specific Activity ◽  
Simple Procedure ◽  
Enzymatic Conversion ◽  
Purification Step ◽  
Angiotensin I ◽  
Low Concentrations ◽  
Chloramine T

ABSTRACT A simple procedure for a reproducible preparation of radioiodinated angiotensin analogues is described. The iodination is performed at a low level of radioactivity – 200 μCi per 10 μg peptide – with low concentrations of chloramine-T and sodium metabisulphite. No destruction of the peptide occurs during the iodination. The yield is high, and the only purification step needed is a separation of iodinated peptide from non-labelled peptide. This separation is performed by means of column chromatography on DEAE-Sephadex A 25. The specific activity of labelled angiotensin I or II prepared by this method was about 500 μCi/μg. The homogeneity of the radioiodinated angiotensin analogues was established by means of paper chromatography and enzymatic degradation studies, including experiments on the enzymatic conversion of 125I-angiotensin I to 125I-angiotensin II. Radiochromatograms obtained after storage for various periods showed perfect stability of the labelled compounds. Immunological characteristics, as evaluated by standard displacement curves with selected antisera and maximal binding to excess antibody, were reproducible from batch to batch.

NEUROHYPOPHYSIAL HORMONES AND RELEASE OF GONADOTROPHINS

1959 ◽  
Vol 18 (3) ◽  
pp. 245-250 ◽  
Author(s):  
L. MARTINI ◽  
L. MIRA ◽  
A. PECILE ◽  
S. SAITO
Keyword(s):  
Intravenous Injection ◽  
Significant Rise ◽  
Normal Female ◽  
Posterior Pituitary ◽  
Mouse Uterus ◽  
Physiological Regulation ◽  
Neurohypophysial Hormones ◽  
Lysine Vasopressin ◽  
Before And After ◽  
Synthetic Oxytocin

SUMMARY The gonadotrophin-releasing activity of hypothalamo-neurohypophysial hormones has been investigated in normal female rabbits. Pooled urine, obtained before and after intravenous injection of different posterior pituitary preparations (Pitressin, Pitocin, lysine-vasopressin and synthetic oxytocin), was extracted by the kaolin-acetone method and assayed by the mouse uterus test. All the posterior pituitary preparations used induced a significant rise in the release of gonadotrophins. The experiments suggest that posterior pituitary polypeptides may play a role in the physiological regulation of gonadotrophin release.

scholarly journals Activation of p56lck through mutation of a regulatory carboxy-terminal tyrosine residue requires intact sites of autophosphorylation and myristylation.

1990 ◽  
Vol 10 (10) ◽  
pp. 5197-5206 ◽  
Author(s):  
N Abraham ◽  
A Veillette
Keyword(s):  
Protein Kinase ◽  
Kinase Activity ◽  
Membrane Association ◽  
Protein Kinase Activity ◽  
Tyrosine Residue ◽  
Amino Terminal ◽  
Enzymatic Function ◽  
Tyrosine Protein Kinase ◽  
Carboxy Terminal

Mutation of the major site of in vivo tyrosine phosphorylation of p56lck (tyrosine 505) to a phenylalanine constitutively enhances the p56lck-associated tyrosine-specific protein kinase activity. The mutant polypeptide is extensively phosphorylated in vivo at the site of in vitro Lck autophosphorylation (tyrosine 394) and is capable of oncogenic transformation of rodent fibroblasts. These observations have suggested that phosphorylation at Tyr-505 down regulates the tyrosine protein kinase activity of p56lck. Herein we have attempted to examine whether other posttranslational modifications may be involved in regulation of the enzymatic function of p56lck. The results indicated that activation of p56lck by mutation of Tyr-505 was prevented by a tyrosine-to-phenylalanine substitution at position 394. Furthermore, activation of p56lck by mutation of the carboxy-terminal tyrosine residue was rendered less efficient by substituting an alanine residue for the amino-terminal glycine. This second mutation prevented p56lck myristylation and stable membrane association and was associated with decreased in vivo phosphorylation at Tyr-394. Taken together, these findings imply that lack of phosphorylation at Tyr-505 may be insufficient for enhancement of the p56lck-associated tyrosine protein kinase activity. Our data suggest that activation of p56lck may be dependent on phosphorylation at Tyr-394 and that this process may be facilitated by myristylation, membrane association, or both.

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