Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:EXPT00572 (Asn)
 11,732 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glycopeptides containing mainly four amino acid residues in the sequence Asn-Leu-Thr-Ser, with small amounts of additional amino acid residues, were isolated from enzymic hydrolysates of hen's-egg albumin. Heterogeneity of the carbohydrate moiety was confirmed. Acid-base titrations showed that the alpha-amino group has a pKa value of 6.43 at 25 degrees C. The standard free engery and entropy changes associated with the ionization at 25 degrees C were 37.2kJ-mol-1 and -0.014kJ-mol-1- K-1 respectively. The complications arising in the interpretation of titration curves of the glycopeptides, which are heterogeneous with respect to the peptide chain, were considered and discussed in the light of the earlier suggestion that the titration curve of the glycopeptide might be interpreted as being due in part to a structure in which the hydroxyl group of the threonine residue is hydrogen-bonded to the beta-aspartamido oxygen atom [Neuberger & Marshall (1968) in Symposium on Foods - Carbohydrates and their Roles (Schultz, H.W., Cain, R.F. & Wrolstad, R.W., eds.), pp. 115-132, Avi Publishing Co., Westport, CT]. It is concluded that either the glycopeptides do not contain a hydrogen bond of that type, or, if they do, that it cannot be recognized by acid-base-titration studies.
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PMID:Acid dissociation constants of glycopeptides. 1 94

Nine synthetic peptides containing sequences in the region of a threonine residue at position 98 of bovine basic myelin protein were prepared by the Merrifield solid-phase method and tested for their ability to be glycosylated with [14C]uridinediphospho-N-acetylgalactosamine and a crude detergent-solubilized preparation of uridinediphospho-N-acetylgalactosamine:mucin polypeptide N-acetylgalactosaminyltransferase obtained from porcine submaxillary glands. The tetrapeptide Thr-Pro-Pro-Pro and all larger peptides containing this sequence were glycosylated. The glycosylation was greater for peptides containing residues N-terminal to the Thr-Pro-Pro-Pro. Under the conditions used, the peptide Val-Thr-Pro-Arg-Thr-Pro-Pro-Pro was glycoslyated twice as much as bovine basic myelin protein. Thr-Pro and Thr-Pro-Pro, as well as 10 other synthetic peptides which did not contain the Thr-Pro-Pro-Pro sequence, were not glycosylated. Treatment of the glycopeptide of Phe-Lys-Asn-Leu-Val-Thr-Pro-Arg-Thr-Pro-Pro-Pro-Ser with an alpha-N-acetylgalactosaminidase released N-acetylgalactosamine from the peptide, indicating that the hexosamine was covalently bonded to the peptide in an alpha linkage.
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PMID:Enzymic O-glycosylation of synthetic peptides from sequences in basic myelin protein. 9 May 21

An improved procedure for automated Edman degradation is presented. Three programs are described, one with double cleavage and two with single cleavage. The programs presented are characterized by a reversed delivery scheme for buffer and phenyl isothiocyanate, and by reduced cleavage times. The modified procedures applied on automated Edman degradation of the vitamin B12-binding proteins human transcobalamin I and human intrinsic factor, containing approximately 390 and 350 amino residues respectively, gave the following N-terminal amino acid sequences: Human transcobalamin I Glu-Ile-Cys-Glu-Val-Ser-Glu-Glu-Asn-Tyr-Ile-Arg-Leu-Lys-Pro-Leu-Leu-Asn-Thr-Met-Ile-Gln-Ser-Asn-Tyr-Asn-?-Gly- Human intrinsic factor Ser-Thr-Gln-Thr-Gln-Ser-Ser-Cys-Ser-Val-Pro-Ser-Ala-Gln-Glu-Pro-Leu-Val-Asn-Gly-Ile-Gln-?-Leu-Met-Glu-Thr- The background accumulation seems to be related not only to the length of the polypeptide chain being degraded, but also to the content of serine (and possibly threonine). A possible N leads to O acyl shift during the cleavage is a tentative explanation. The programs here represented lead to a significant reduction in background compared to conventional programs and allowed considerable prolongation of the degradations.
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PMID:An improved procedure for automated Edman degradation used for determination of the N-terminal amino acid sequence of human transcobalamin I and human intrinsic factor. 18 65

A rapid purification procedure for large scale preparations of yeast proteinase B inhibitors 1 and 2 (IB1 and IB2) is described. By disc gel electrophoresis, amino acid analysis, and end-group determinations, each of the inhibitors is homogeneous. Both inhibitors are polypeptides with molecular weights of 8,500, containing 74 residues. No components other than amino acids could be detected. There is no significant difference in the amino acid compositions of the two inhibitors as analyzed after acid hydrolysis. Both polypeptides are characterized by the total absence of arginine, tryptophan, and sulfur-containing amino acid residues. The proteinase B inhibitors of yeast, therefore, differ fundamentally from proteinase inhibitors of many other organisms, which generally contain a large number of disulfide bridges. Both proteinase B inhibitors have threonine as the NH2-terminal residue and -Val-His-Thr-Asn-COO- as the COOH-terminal sequence. Comparison of peptide maps after tryptic digestion reveals that the two inhibitors differ definitely in only a few tryptic peptides. The inhibitors are rapidly inactivated by digestion with carboxypeptidase A from bovine pancreas at pH 8.5. Inactivation occurs stoichiometrically with the release of threonine, the penultimate residue at the COOH-terminal end of both inhibitors.
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PMID:Purification and molecular characterization of two inhibitors of yeast proteinase B. 38 8

[1-Deaminopenicillamine,4-threonine]oxytocin was prepared in duplicate from S-benzyl-3-mercapto-3,3-dimethylpropanoyl-Tyr(Bzl)-Ile-Thr(Bzl)-Asn-Cys(Bzl)-Pro-Leu-Gly-NH2 (I) by removal of the Bzl-protecting groups with Na-NH3, followed by cyclization of the resulting disulfhydryl compound with K3Fo(CN)6. The analogue was purified by desalting on Sephadex G-15 in 50% acetic acid and gel filtration of Sephadex G-15. The protected peptide I was synthesized (a) by the solid-phase method and (b) by a combination of solid-phase synthesis and an [8 + 1] coupling in solution. The analogue has no detectable agonist activity in rat vasopressor or isolated rat uterus assays. It has an antivasopressor pA2 of 6.67 +/- 0.09. It is a potent inhibitor of the in vitro oxytocic response to oxytocin and has a pA2 value of 7.46 +/- 0.04. (Material from the repeat synthesis has a pA2 value of 7.59 +/- 0.08.) Thus the substitution of threonine for glutamine in the antagonist [1-deaminopenicilliamine]oxytocin (pA2, 7.14 +/- 0.05) has effected a twofold increase in inhibitory potency. [1-deaminopenicillamine,4-threonine]oxytocin is one of the most potent inhibitors of oxytocin known to date.
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PMID:[1-Deaminopenicillamine,4-threonine]oxytocin, a potent inhibitor of oxytocin. 62 12

Cow colostrum trypsin inhibitor (chromatographic form AIV[7])was subjected to basic conditions that favour beta-elimination of carbohydrates from O-glycosidic linkages. The unchanged carbohydrate composition and the unchanged values for serine and threonine indicate the presence of an alkali-stable N-glycosidic bond to asparagine. From a tryptic digest of S-aminoethylated inhibitor the glyco-decapeptide (residues 24 through 33) was isolated. The carbohydrate composition was identical with that of the S-aminoethylated inhibitor. Further degradation of this peptide by carboxypeptidase C (and aminopeptidase) produced the glycopeptide Asn(CHO)-Ser-(Thr) with the same carbohydrate composition. Thus, a single carbohydrate moiety is bound by a N-glycosidic linkage to asparagine-27 of the colostrum inhibitor. It is located opposite to the reactive site at the base of a pear-shaped molecule.
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PMID:The carbohydrate linkage site of cow colostrum trypsin inhibitor. 64 52

A series of compounds structurally related to adipokinetic hormone, the decapeptide neurohormone less than Glu-Leu-Asn-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2, have been prepared by synthesis and by enzymic cleavages of synthetic hormone. Their relative agonist activities in mobilising lipids over a fixed time interval (1 h) in locusts were assessed. The similar time courses for lipid release shown by two of the peptide analogues and adipokinetic hormone suggest that the analogues and the hormone are transported to the receptors on the fat body cells, and are also degraded, at similar rates. Consequently, the analogue activities can be correlated with the structural requirements of the locust fat body hormone receptors. The requirements for activity demonstrated in this study are as follows. Residues 1--8 from the N-terminus are necessary to elicit some activity (20%). Residues 5 and 7 in the octapeptide can be changed without affecting activity but L-pyroglutamic acid as the N-terminal residue is necessary formaximum activity both in the octapeptide and the decapeptide. Full activity is achieved only by adding the dipeptide glycyl threonine amide to the active octapeptide 'core'. In the decapeptide, residues cannot be interchanged to the same extent as in the octapeptide without reducing activity. The peptide probably has to be uncharged. Inactive analogues of seven residues or less do not interfere in the hormone-receptor interaction.
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PMID:Structure-activity relationships for the lipid-mobilising action of locust adipokinetic hormone. Synthesis and activity of a series of hormone analogues. 69 7

The amino acid sequence for vitamin D-dependent bovine intestinal calcium binding protein has been established. It contains 85 amino acids in a single chain and lacks cysteine, tryptophan, methionine, histidine, and arginine. The NH2-terminal lysine is blocked by an N-acetyl group. Enzymatic digestion with trypsin, chymotrypsin, and pepsin yielded a number of peptides which were purified by two-dimensional high voltage paper electrophoresis. These peptides were examined by end group analysis and sequenced by the dansyl procedure. The absence of tryptophan permitted by a single cleavage of the molecule by N-bromosuccinimide at the tyrosine residue at position 8 and the larger fragment was subjected to automated Edman degradation. By these means, the following sequence was established: N-Ac-Lys-Gln-Ser-Pro-Leu-Glu-Tyr-Ala-Ala-Glu-Lys-Ser-Ile-Gln-Lys-Glu-Ile-Glu-Lys-Gly-Phe-Phe-Lys-Gln-Leu-Leu-Val-Ser-Val-Gln-Lys-Ala-Gly-Asp-Lys-Glu-Ser-Leu-Gln-Pro-Leu-Phe-Thr-Leu-Leu-Lys-Ser-Gly-Pro-Glu-Glu-Asn-Leu-Lys-Glu-Ser-Gln-Asn-Gly-Pro-Asp-Leu-Ls7-Ser-Gly-Pro-Gly-Asn-Asp-Leu-Glu-Glu-Lys-Gly-Thr-Asp-Val-Phe-Ser-Leu-Lys-Gln. Microheterogeneity may exist in the molecule at residue 76 in which position threonine may be replaced by serine. Comparison of the sequence of calcium-binding protein to the "test" sequence of Tufty and Kretsinger ((1975) Science 187, 167-169) proposed to identify E-F hands in muscle proteins suggests that intestinal calcium-binding protein may likewise contain one or possibly two E-F hands which could account for calcium-binding property. Dayhoff alignment scores, however, calculated for calcium-binding protein against nine E-F hands in muscle proteins parvalbumin, troponin and alkali light chains do not indicate that intestinal calcium-binding protein is homologous to these muscle protein chains.
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PMID:Calcium-binding protein of bovine intestine. The complete amino acid sequence. 117 41

The most abundant protein found in blood plasma from the sea lamprey (Petromyzon marinus) has the hallmarks of a plasma albumin: namely, high abundance, solubility in distilled water, a small number of tryptophans, and a high content of cysteines and charged residues. As in other vertebrate albumins, not all the cysteines are disulfide bonded. An unusual feature of this protein is its molecular weight of 175,000, roughly 2.5 times the size of other vertebrate albumins. Its amino acid sequence, deduced from a series of overlapping cDNA clones, can be aligned with other members of the gene family including plasma albumin, alpha-fetoprotein, and vitamin-D binding protein, confirming that it is indeed an oversized albumin. An unusual feature of the sequence is a 28-amino acid stretch consisting of a serine-threonine repeat with the general motif (STTT). Lamprey albumin contains a 23-amino acid putative signal peptide and a 6-residue putative propeptide, which, when cleaved, yield a mature protein of 1,394 amino acids with a calculated molecular weight of 157,000. The sequence also includes nine potential N-linked glycosylation sites (Asn-X-Ser/Thr), consistent with observation that lamprey albumin is a glycoprotein. If all the potential glycosylation sites were occupied by clusters of 2,000 molecular weight each, the total molecular weight would be 175,000. Like other members of the gene family, lamprey albumin is composed of a series of 190-amino acid repeats, there being seven such domains all together. Quantitative amino acid sequence comparisons of lamprey albumin with the other members of the gene family indicate that it diverged from an ancestral albumin prior to the gene duplications leading to this diverse group. This notion is confirmed by the pattern of amino acid insertions and deletions observed in a consideration of all domains that compose this family. Furthermore, it suggests that the invention of albumin antedates the vertebrate radiation.
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PMID:Characterization, primary structure, and evolution of lamprey plasma albumin. 130 10

The bacteriophage T7 0.7 gene encodes a protein which supports viral reproduction under specific suboptimal growth conditions. The 0.7 protein (gp0.7) shuts off host RNA polymerase-catalyzed transcription and also expresses a serine/threonine-specific, cAMP-independent protein kinase (PK) activity. To determine the role of the gp0.7 PK in viral reproduction, the 0.7 gene of the T7(JS78) mutant phage--whose gp0.7 expresses only the PK activity--was cloned in the plasmid expression vector pET-11a. Cells containing the recombinant plasmid were viable, and upon IPTG induction produced a 30-kDa polypeptide, similar in size to the gp0.7-related polypeptide seen in T7(JS78)-infected cells. Extracts of cells containing this polypeptide can phosphorylate the exogenous substrate lysozyme. Expression of plasmid-encoded gp0.7(JS78) in vivo results in phosphorylation of the same proteins which are phosphorylated in T7(JS78)-infected cells; moreover, the plasmid-encoded gp0.7(JS78) is itself phosphorylated. The JS78 mutation changes Gln243 in gp0.7 to an amber codon, which explains the production of the truncated, 30-kDa gp0.7-related polypeptide, and implicates the 11-kDa C-terminal domain in host transcription shut-off. The T7(A23) 0.7 point mutant fails to express PK activity in infected cells. However, the truncated T7(A23)-related polypeptide, expressed from a plasmid, exhibits PK activity in vivo and in vitro, but with an altered specificity. Thus, the A23 mutation, which changes Asp100 to Asn, may identify a substrate recognition determinant.
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PMID:Molecular cloning and expression of the bacteriophage T7 0.7(protein kinase) gene. 131 Jan 78


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