Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have labeled the large fragment of Escherichia coli DNA polymerase I (Pol I) with pyridoxal 5'-phosphate, a substrate binding site directed reagent for DNA polymerases [Modak, M. J. (1976) Biochemistry 15, 3620-3626]. A covalent attachment of pyridoxal phosphate to Pol I results in the loss of substrate binding as well as the polymerase activity. The inactivation was found to be strictly dependent on the presence of a divalent metal ion. Four moles of pyridoxal phosphate was found to react per mole of the enzyme, while in the presence of substrate deoxynucleoside triphosphate only 3 mol of pyridoxal phosphate was bound. To identify the substrate-protected site on the enzyme, tryptic peptides from enzyme labeled with pyridoxal phosphate and tritiated borohydride, in the presence and absence of substrate, were resolved on a C-18 reverse-phase column. A single peptide containing the substrate-protected site was identified and further purified. The amino acid composition and sequence analysis of this peptide revealed it to span residues 756-775 in the primary acid sequence of Pol I. Lys-758 of this sequence was found to be the site of the pyridoxal phosphate reaction. It is therefore concluded that Lys-758 is the site of binding for the metal chelate form of nucleotide substrates in E. coli DNA polymerase I.
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PMID:Identification and amino acid sequence of the deoxynucleoside triphosphate binding site in Escherichia coli DNA polymerase I. 329 33

Rabbit skeletal muscle calsequestrin was fragmented by using trypsin in the presence and absence of calcium. Calcium ion was found to protect calsequestrin from proteolysis, and the peptides produced in the presence of calcium were stable to further digestion. Peptides produced in the presence or absence of calcium had a decreased helical content but maintained their ability to bind calcium. The amino acid sequence of a 59-residue carboxyl-terminal tryptic peptide was determined by automated Edman degradation and carboxypeptidase Y digestion of carboxyl-terminal tryptic, chymotryptic, and cyanogen bromide peptides. This peptide is highly acidic (Asp + Glu = 42%, Lys + Arg = 0), and it bound a total of 15 calcium ions per mole of peptide (Kd = 8.5 mM). The intrinsic tryptophan fluorescence of the peptide was enhanced by 10% upon binding Ca2+ with the dissociation constant of 1 mM. Analyses of the circular dichroism spectra of the peptide showed that it was primarily in a random-coil conformation with little helical (2%) and moderate beta-structure (25%) regardless of the calcium concentration. This peptide also bound 7 mol of terbium per mole of peptide with high affinity (Kd = 7.5 microM).
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PMID:Fragmentation of rabbit skeletal muscle calsequestrin: spectral and ion binding properties of the carboxyl-terminal region. 342 87

Protease A of Bitis arietans venom is probably a metalloprotease, since it is inhibited by o-phenanthroline and contains 0.77 moles of zinc per mole protein. The enzyme comprises 213 amino acids, including 9 methionine residues and one free sulphydryl group. It contains one polypeptide chain, which is terminated at the carboxyl end by serine. The amino terminal sequence of protease A is: Arg-Ser-Ser-Asp-Pro-Asn-Lys-Tyr-Phe-Asn-Val-Ile-Val-Val-Val-Asp-Asn-Arg- Met-Val-Asn-Tyr-Tyr-Lys-Gly-Glu-Leu-Asn-Lys-Ile-Thr-. Despite difficulties with 'insoluble peptide core' formation, a number of peptides were purified from peptic and tryptic digests of S-derivatized protease A.
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PMID:Chemical studies on protease A of Bitis arietans (puff adder) venom. 352 Sep 56

An alanine racemase, encoded by the alr (dal) gene and believed to be the biosynthetic source of D-alanine for cell wall formation, was purified to homogeneity from an overproducing strain of Salmonella typhimurium (dadB), and the enzymological properties of this enzyme were compared with those of the dadB alanine racemase that functions in the catabolism of L-alanine [Wasserman, S. A., Daub, E., Grisafi, P., Botstein, D., & Walsh, C. T. (1984) Biochemistry 23, 5182]. The alr-encoded enzyme has a monomeric structure with a molecular weight of about 40 000. One mole of pyridoxal 5'-phosphate is bound per mole of enzyme, which is essential for catalytic activity of the enzyme. After the internal Schiff base with pyridoxal 5'-phosphate was reduced with NaB3H4, followed by carboxamidomethylation and tryptic digestion of the enzyme, the amino acid sequence of the pyridoxal 5'-phosphate binding peptide was determined. The sequence of 10 amino acid residues around the lysine residue, to which pyridoxal 5'-phosphate is bound, was identical with that of the dadB racemase. No homology was found in the amino-terminal amino acid sequence between the two enzymes. The enzyme was inactivated with D- and L-beta-fluoroalanine, D- and L-beta-chloroalanine, and D-O-acetylserine in a mechanism-based fashion with a common partition ratio of about 150. The enzyme was labeled with an equimolar amount of [14C]-D-beta-chloroalanine. The inactivator-pyridoxal 5'-phosphate adduct was isolated and shown to be the same structure formed in the dadB racemase inactivation [Roise, D., Soda, K., Yagi, T., & Walsh, C. (1984) Biochemistry 23, 5195].
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PMID:Biosynthetic alanine racemase of Salmonella typhimurium: purification and characterization of the enzyme encoded by the alr gene. 352 77

A basic (pI = 10.2) phospholipase A2 of the venom of the snake Agkistrodon halys blomhoffii is one of a few phospholipases A2 capable of hydrolyzing the phospholipids of Escherichia coli killed by a bactericidal protein purified from human or rabbit neutrophil granules. We have shown that modification of as many as 4 mol of lysine per mole of the phospholipase A2, either by carbamylation or by reductive methylation [Forst, S., Weiss, J., & Elsbach, P. (1982) J. Biol. Chem. 257, 14055-14057], had no effect on catalytic activity toward extracted E. coli phospholipids or the phospholipids of autoclaved E. coli. In contrast, modification of 1 mol of lysine per mole of enzyme substantially reduced activity toward the phospholipids of E. coli killed by the neutrophil protein. To explore further the role of lysines in the function of this phospholipase A2, we determined the amino acid sequence of the enzyme and the incorporation of [14C]cyanate into individual lysines when, on average, 1 lysine per molecule of enzyme had been carbamylated. After incorporation of approximately 1 mol of [14C]cyanate per mole of protein, the phospholipase A2 was reduced, alkylated, and exhaustively carbamylated with unlabeled cyanate. The amino acid sequence was determined of the NH2-terminal 33 amino acids of the holoprotein and of peptides isolated after digestion with trypsin and Staphylococcus aureus V-8 protease. The protein contains 122 amino acid residues, 17 of which are lysines. The NH2-terminal region is unique among more than 30 phospholipases A2 previously sequenced because of its high content of basic residues (His-1, Arg-6, and Lys-7, -10, -11, and -15).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Amino acid sequence of a basic Agkistrodon halys blomhoffii phospholipase A2. Possible role of NH2-terminal lysines in action on phospholipids of Escherichia coli. 353 Mar 22

We report results of chromatographic, pH titration and nuclear magnetic resonance (NMR) spectroscopy studies demonstrating that the bovine pineal antireproductive tripeptide, Thr-Ser-Lys (BPART), binds to luteinizing hormone-releasing hormone (LHRH) at a site comprised of LHRH 2-5 (His-Trp-Ser-Tyr). BPART and LHRH have been shown to be antagonists in vitro. The binding constant is ca. 2 X 10(3)/mole. An NMR study of fifty other peptide pairs demonstrates that the binding is sequence and residue specific. The binding provides evidence of the amino acid pairing hypothesis, and suggests the possibility of modulation of one peptide by directly binding with another peptide.
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PMID:Bovine pineal antireproductive tripeptide binds to luteinizing hormone-releasing hormone: a model for peptide modulation by sequence specific peptide interactions? 353

Creatine kinase from skeletal muscle (EC 2.7.3.2) was inactivated by means of imidazolides of AMP, ADP, ATP. Rates of the inactivation of the enzyme's M- and M'-subunits differ 50-100 fold and decrease in the presence of ADP and ATP. Differential spectrum of the native and modified enzymes corresponds to the spectrum of N,O-diacetyltyrosine. Kinetic curves of hydroxylamine-dependent destruction of N,O-diacetyltyrosine and of alteration of differential spectrum of the modified and native enzymes essentially coincide. The enzyme's inactivation appears to be caused mainly by the formation of a bond between nucleotide imidazolides activated carboxyl group of the active centre and OH-group of Tyr residue arranged in the close proximity. The stoichiometry of acyltyrosine formation is evaluated as 2.1 +/- 0.2 mole per mole of the functional dimer. Along with formation of ester bond between amino acid residues, a covalent attachment of 0.03-0.06 mole of [14C]nucleotides per mole of enzyme is observed. As the data of acid hydrolysis show, Im-ATP and Im-AMP block epsilon-amino group of Lys and guanidine group of Arg, respectively. Reasons of the multiple modification of creatine kinase by affinity reagents are discussed. The results obtained and literature data are summarised in the hypothetical scheme of disposition of various amino acid residues in the active centre of creatine kinase.
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PMID:[Creatine kinase from rabbit skeletal muscles: formation of O-acyltyrosine as a result of the activation of the carboxylic group of the enzyme active site by affinity reagents, nucleotide imidazolides]. 360 72

The 31P NMR method was first applied to characterize in vivo phosphorylation of H1 and H5 in calf thymus and chicken erythrocytes as well as in vitro phosphorylation of H1 and H5 by cAMP-dependent protein kinase. The amino acid residues phosphorylated in vivo in the histones were exclusively serine residues, and the mole fraction of phosphoserine was estimated to be 0.34 and 0.27 per molecule of calf thymus H1 and chicken erythrocyte H5, respectively. Interestingly, chicken erythrocyte H1 was not phosphorylated in vivo. Three H1 subtypes from calf thymus H1 varied in the 31P NMR spectra, and the bisected fragments of calf thymus H1 and chicken erythrocyte H5 exhibited characteristic spectral patterns, indicating that there are considerable diversities of the degree of phosphorylation and phosphorylation sites in very-lysine-rich histones. Furthermore, it was found that the microenvironment of phosphoserine residues phosphorylated in vivo in calf thymus H1 and chicken erythrocyte H5 is quite distinct from that of phosphoserine residues phosphorylated in vitro by bovine heart cAMP-dependent protein kinase.
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PMID:In vivo phosphorylation of histones H1 and H5 in calf thymus and chicken erythrocyte as studied by 31P nuclear magnetic resonance spectroscopy. 366 74

Diabetic patients in poor glycemic control show increased glycation of total plasma proteins, but little is yet known about the relative extents to which the various individual proteins are glycated. Thus, we studied the non-enzymic glycation of several major plasma proteins and plasma protein fractions in normal and diabetic patients. In vivo glycation for most plasma proteins was very low in non-diabetic patients, only gamma globulin showing more than 5% glycation. In diabetic plasmas, glycation was much greater, immunoglobulins again showing the greatest proportion, followed in descending order by albumin, complement C3, fibrinogen, transferrin, haptoglobin, and alpha-1-antitrypsin. When plasma proteins were glycated in vitro, this order was IgG greater than complement C3 greater than albumin greater than transferrin greater than haptoglobin greater than alpha-1-antitrypsin. In general, proteins with the longest biological half-lives, such as IgG and albumin, showed the greatest in vivo glycation. On the other hand, proteins with high intrinsic glycability, such as complement C3, showed moderate glycation, despite a short half-life. Except for albumin, more basic proteins showed greater glycation than acidic proteins, but there was poor correlation between mole percent lysine and glycation. Evidently the relative extents of glycation of different plasma proteins are a complex function of integrated glucose concentrations over time and of the half-life and chemical characteristics of each protein.
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PMID:Non-enzymic glycation of individual plasma proteins in normoglycemic and hyperglycemic patients. 369 Aug 40

Apparent kinetic constants (Km and Vmax values) were determined for human liver acyl-CoA: glycine acyltransferase (glycine-N-acylase) towards isobutyryl-CoA, 2-methyl butyryl-CoA, isovaleryl-CoA, butyryl-CoA, hexanoyl-CoA, octanoyl-CoA, and decanoyl-CoA. These acyl-CoA esters were selected because of their relevance to the human diseases with cellular accumulation of these esters, i.e., especially to metabolic defects in the acyl-CoA dehydrogenation steps of the branched-chain amino acids, lysine, 5-hydroxy lysine, tryptophan, and fatty acid oxidation pathways. With the acyl-CoA ester as the fixed substrate, the Km value for glycine ranged from 0.5 to 2.9 mole/liter, and with glycine as fixed substrate, the Km values for the acyl-CoA esters varied from 0.3 to 5.6 mmole/liter. It is concluded that the substrate concentration is decisive for the glycine conjugate formation and that the occurrence in urine of acylglycines reflects an intramitochondrial accumulation of the corresponding acyl-CoA ester.
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PMID:Acyl-CoA: glycine N-acyltransferase: in vitro studies on the glycine conjugation of straight- and branched-chained acyl-CoA esters in human liver. 370 52


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