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)

Heterogeneities of the two ovalbumin glycopeptides, (Man)5(GlcNAc)2Asn and (Man)6(GlcNAc)2Asn, were revealed by borate paper electrophoresis of oligosaccharide alcohols obtained from the glycopeptides by endo-beta-N-acetylglucosaminidase H digestion and NaB3H4 reduction. The structures of the major components of the oligosaccharides were determined by the combination of methylation analysis, acetolysis, and alpha-mannosidase digestion. Based on the results, the whole structures of the major components of (Man)5(GlcNAc)2Asn and (Man)6(GlcNAc)2Asn were elucidated as Manalpha1 leads to 6[Manalpha1 leads to 3]-Manalpha1 leads to 6[Manalpha1 leads to 3[Manbeta1 leads to 4GlcNAcbeta1 leads to 4GlcNAc leads to Asn and Manalpha1 leads to 6[Manalpha1 leads to 3]Manalpha1 leads to 6[Manalpha1 leads to 2Manalpha1 leads to 3]Manbeta1 leads to 4GlcNAcbeta1 leads to GlcNAc leads to Asn, respectively. Since endo-beta-N-acetylglucosamini dase D hydrolyzes (Man)5(GlcNAc)2Asn but not (Man)6(GlcNAc)2Asn, the presence of the unsubstituted alpha-mannosyl residue linked at the C-3 position of the terminal mannose of Manbeta1 leads to 4GlcNAcbeta1 leads to 4 GlcNAcAsn core must be essential for the action of the enzyme.
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PMID:Structural studies of two ovalbumin glycopeptides in relation to the endo-beta-N-acetylglucosaminidase specificity. 0 Mar 89

The membrane penicillinase of Bacillus licheniformis 749/C has been demonstrated to be a phospholipoprotein. The homogeneous enzyme gives a positive reaction for phosphorous and for unsaturated fatty acids, has a molecular weight of 33,000 in contrast to 29,000 for the exoenzyme, and contains 8 to 9 additional residues of aspartate or asparagine, 4 to 5 of serine, 7 of glutamate or glutamine, and 4 to 5 of glycine per mole. The COOH-terminal sequence of both membrane and exoenzymes is -Met-Asn-Gln-Lys-COOH; hence the extra peptide portion present in the membrane enzyme is not attached to the COOH-terminus of the exoenzyme. Procedures which readily detected the lysine residue at the NH2 terminus of the exoenzyme did not yield a positive test with the membrane form. The NH2 terminus of the membrane enzyme may be blocked by or linked to the phospholipid. A procedure for the preparation of membrane penicillinase on a large scale and an improved method for purification of the exoenzyme have been developed.
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PMID:Purification of plasma membrane penicillinase from Bacillus licheniformis 749/C and comparison with exoenzyme. 0 71

beta-D-Mannosidase (EC 3.2.1.25), a useful tool for the structural studies of heterosaccharide chains, has been isolated in a highly purified form from the fruiting bodies of the mushroom Polyporus sulfureus. This mushroom is unique among reported sources of this enzyme in that it has the advantage of being almost free of alpha-mannosidase activity. The purification procedure involves ammonium sulfate fractionation followed by Sephadex G-100 filtration and chromatography on columns of DEAE-cellulose and hydroxylapatite. The final enzyme preparation gives essentially a single band on disc gel electrophoresis. The purified enzyme liberates the beta-D-mannopyranosyl unit from various natural substrates such as the core glycopeptide, Man(GlcNAc)2-Asn isolated from ovalbumin, from Taka-amylase A, and from human alpha1-acid glycoprotein. It also hydrolyzes (Man)2-GlcNAc from the urine of an alpha-mannosidosis patient, 1,4-D-mannobiose and mannotriose isolated from ivory nut mannan, 4-O-beta-D-mannopyranosyl-L-rhamnose, 6-O-beta-D-mannopyranosyl-D-galactose and 4-O-beta-D-mannopyranosyl-N-acetylglucosamine. The molecular weight of this enzyme is estimated to be about 64,000 by gel filtration. For p-nitrophenyl-beta-D-mannopyranoside, the pH optimum is between 2.4 and 3.4 and the Km is 1.6 mM.
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PMID:beta-Mannosidase from the mushroom Polyporus sulfureus. 0 78

Hemoglobin from an adult camel (Camelus dromedarius) was prepared from the red cell lysate by CM- and DEAE-cellulose chromatography. The purified hemoglobin showed a lesser mobility on starch gel electrophoresis at pH 8.5 than that of human hemoglobin C. Native camel hemoglobin contains 95-99% alkali-resistant hemoglobin and in soluble in 2.94 M K2HPO4/KH2PO4 buffer. Different forms of camel hemoglobin show similar ammonium sulfate precipitation curves. Indirect evidence for the stability of camel hemoglobin solutions was obtained from several sources. Spontaneous met-hemoglobin formation is extremely slow and minimal quantities of degradation products appear on starch gel electrophoresis and on chromatographic separation. The alpha and beta chains of camel hemoglobin A were separated on a CM-23 column by the use of a pyridine formate gradient. Large peptide fragments were obtained by tryptic digestion of maleylated alpha and beta chains. The N-terminal structure of the alpha and beta chains and of tryptic maleylated peptides derived from alpha and beta chains are presented. Between adult camel hemoglobin and adult human hemoglobin six amino acid differences in the N-terminal 20 amino acid residues of the alpha chain, at residues: 4, 5, 12, 14, 17, and 19; eight amino acid substitutions were found in the beta chain at positions: 4, 5, 6, 9, 12, 13, 16, and 19. Substitutions at alpha5 Ala leads to Lys, and beta19 Asn leads to Lys, increase the net positive charge of camel hemoglobin by two, while other substitutions result in no charge differences. The molecular basis of the stability of camel adult hemoglobin is discussed.
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PMID:Studies on camel hemoglobin. 1. Physico-chemical properties and some structural aspects of camel hemoglobin (Camelus dromedarius). 0 5

A non-heme iron protein, rubredoxin has been isolated from the sulfate-reducing bacterium, Desulfovibrio vulgaris, strain Hildenborough. The complete amino acid sequence has been established. The 52 amino acid residues of the protein were aligned with the aid of tryptic and chymotryptic peptides and of a fragment produced by cleavage of the Asn-Gly bond (22-23) by hydroxylamine. The sequence of the first 30 residues of the molecule was determined using an automatic sequenator, after removal of the N-terminal methionine by CNBr. In comparing this sequence with those of Micrococcus aerogenes, Clostridium pasteurianum and Peptostreptococcus elsdenii rubredoxins, a high degree of mutation was observed between these homologous proteins. It has been shown that 20 amino acid residues occurred in identical positions. The locations of the four cysteine residues were found to be invariable. A crystallographic study of the Desulfovibrio vulgaris rubredoxin is in progress.
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PMID:Non-heme iron proteins. The amino acid sequence of rubredoxin from Desulfovibrio vulgaris. 0 8

The NADP-specific glutamate dehydrogenase (EC 1.4.1.4) of Neurospora crassa is inhibited by reaction with 1,2-cyclohexanedione which binds to arginine residues. With the 14C-labeled reagent, a peptide was isolated with the sequence: Gly-Gly-Leu-Arg-Leu-His-Pro-Ser-Val-Asn-Leu, corresponding to residues 78 through 88 in the protein. The arginine, residue 81, was present as N7,N8-(1,2-dihydroxycyclohex-1,2-ylene)-arginyl (or DHCH-arginine). Present evidence indicates that this arginine residue resides at or near the nicotinamide binding domain of the enzyme. Similar sequences are present in the bovine liver enzyme (EC 1.4.1.3) and the NAD-specific glutamate dehydrogenase of Neurospora (EC 1.4.1.2).
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PMID:Identification of a functional arginine residue involved in coenzyme binding by the NADP-specific glutamate dehydrogenase of Neurospora. 0 4

Position beta 82 in human hemoglobin (Hb) is normally occupied by lysine, a positively charged residue that is involved in the binding of anionic cofactors. This residue is substituted by a neutral residue in Hb Providence Asn and by a negatively charged residue in Hb Providence Asp. Hb Providence Asp shows more differences from Hb A than does Hb Providence Asn in studies of the kinetics and equilibria of ligand binding. For both forms, homotropic (cooperative) interactions are normal with n values of 2.5 to 2.7, while heterotropic (pH and anion) interactions are reduced greatly. The reduction in anion sensitivity is attributed to the absence of a positive residue at position beta 82. Reduction in pH sensitivity may be due to a ligand-linked change in the pK of a neighboring residue, beta 143 histidine, which normally is not a Bohr group. This change in pK would act in opposition to the normal Bohr effect. Reduction in the net positive charge of the central cavity has a further consequence. Relative to Hb A, both Hb Providence Asn and Hb Providence Asp show decreased oxygen affinities at neutral pH in the absence of cofactors. This suggests that in Hb A the binding of anionic cofactors directly influences the oxygen affinity by neutralizing the charged groups of the diphosphoglycerate binding site and thus stabilizing the low affinity (T) conformation. From pH 6 to 9 in the presence of 1 M NaCl, where all the charged groups may be masked, the oxygen-binding properties of Hb A and the Hb Providence mutants are identical. Moreover, subunit dissociation of the liganded Hb Providence mutants appears to be increased, as is known to occur for Hb A in the presence of high salt. The results obtained with Hb Providence Asn and Hb Providence Asp illustrate how single amino acid substitutions can modify hemoglobins' pH and anion interactions without altering cooperative interactions between subunits. The alteration in cofactor effects observed with these mutants also illustrates differences between the allosteric effects induced by organic and inorganic anions.
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PMID:Hemoglobin providence. Functional consequences of two alterations of the 2,3-diphosphoglycerate binding site at position beta 82. 1 72

A highly potent heart stimulant, anthopleurin A, from Anthopleura xanthogrammica was shown to exist as a single polypeptide chain consisting of 49 amino acid residues. The sequence of the peptide was shown to be: Gly-Val-Ser-Cys-Leu-Cys-Asp-Ser-Asp-Gly-Pro-Ser-Val-Arg-Gly-Asn-Thr-Leu-Ser-Gly-Thr-Leu-Trp-Leu-Tyr-Pro-Ser-Gly-Cys-Pro-Ser-Gly-Trp-His-Asn-Cys-Lys-Ala-His-Gly-Pro-Thr-Ile-Gly-Trp-Cys-Cys-Lys-Gln as judged by Edman degradation of the carboxymethylcysteine derivative and the tryptic peptides obtained from the derivative. Although six carboxymethylcysteine residues were present in the polypeptide, no cysteine residues were detectable in the native protein, indicating that there are three cystine residues in anthopleurin A.
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PMID:Amino acid sequence of the Anthopleura xanthogrammica heart stimulant, anthopleurin A. 1 6

The amide content of neocarzinostatin (NCS), an antitumor protein, has been determined by analysing asparagine and glutamine in the Pronase-aminopeptidase M digests of tetra-S-carboxymethyl-NCS and carboxyl-modified NCS (modified with a water-soluble carbodiimide and [14C]glycine methyl ester). Preneocarzinostatin (PRE) was separated and purified from a crude NCS preparation by CM-cellulose column chromatography. PRE was found to contain one mole less asparagine than NCS, and asparagine was deamidated to aspartic acid in PRE. A time-dependent conversion of NCS to PRE at pH 3.2 at 4 degrees or in 0.1 M acetic acid at 26 degrees was studied in two ways; first, by quantitative determination of NCS and PRE by CM-cellulose column chromatography and second, by following the release of free NH3 during dialysis in an air-tight container. Within experimental error, PRE was indistinguishable from NCS in amino acid content after acid hydrolysis, as well as in apparent molecular weight as determined by SDS-disc gel electrophoresis (10% acrylamide), and N- and C-terminal amino acid residues. Both NCS and PRE shared a common antigenicity as determined by Ouchterlony's agar diffusion method. Only a slight difference between the two in electrophoresis on a cellulose acetate membrane and on a peptide map of the tryptic digest was demonstrated. PRE, however, was completely devoid of biological activity. In addition to the chromatographic difference, a conformational difference was observed by CD spectroscopy, namely, an apparently looser structure of PRE was indicated by the shallowness of the trough in the 240-265 nm region. This interpretation was supported by the finding that digestions by Pronase were more extensive with PRE than with NCS. These results indicate an important role of the single asparagine residue (Asn 83) of NCS in the biological activity, which is evidently governed by the conformation.
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PMID:Spontaneous deamidation of a protein antibiotic, neocarzinostatin, at weakly acidic pH. Conversion to a homologous inactive preneocarzinostatin due to change of asparagine 83 to aspartic acid 83 accompanied by conformational and biological alterations. 1 34

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


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