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)

Human carboxypeptidase A has been isolated from activated pancreatic juice by means of affinity chromatography employing the competitive inhibitor benzylsuccinic acid as an affinity ligand. The structural and functional features of the human and bovine enzymes are quite analogous. The molecular weights of human and bovine carboxypeptidases A are virtually identical, their amino acid compositions are similar, both contain 1 g-atom of zinc/mole, and the activities of both are restored by addition of zinc to the apoenzyme. The inhibition of human carboxypeptidase by chelating agent is reversed by either dilution or addition of a metal such as Cu2+. When other metals are substituted for the native zinc, peptidase activity of the human metallocarboxypeptidases follows the order: cobalt greater than nickel greater than manganese greater than cadmium, while the sequence for esterase activities is: manganese greater than cobalt = cadmium greater than nickel. The latter sequence differs from that observed for the bovine enzyme. Human carboxypeptidase A crystallizes after dialysis at low ionic strength. Hydrolysis of the dipeptide carbobenzoxyglycyl-L-phenylalanine and of the ester benzoylglycyl-L-alpha-hydroxy-beta-phenyllactate exhibits kinetic anomalies, but that of their longer homologues does not. Chemical modifications with tyrosine reagents alters esterase and peptidase activities. The affinity chromatographic method here described should greatly facilitate future studies of this enzyme from human and other sources.
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PMID:Purification and crystallization of human carboxypeptidase A. 93 22

A naturally occurring monodisperse Cu-thionein was prepared using ammonium sulfate precipitation followed by ion exchange (DEAE 23) and gel chromatography (Sephadex G-75). The chromatographic steps were repeated at least twice, or until the Cu-thionein remained homogeneous when subjected to analytical polyacrylamide disc electrophoresis. The molecular weight of this copper protein was 9500+/-500. Up to 24.3% cysteine residues were determined, indicating the relationship to the metallothioneins. Aromatic amino acids were virtually absent, while there were about three times as many acidic amino acid residues, including aspartate and glutamate, as in metallothioneins. 10 g atoms of Cu were measured per mole of protein. The copper binding strength of thionein was extremely high. Displacement by protons (pH 1.5) and gel chromatography or dialysis employing EDTA were not effective. Dialysis against diethyldithiocarbamate produced a protein essentially free of copper. Both the ultraviolet properties and the circular dichroism measurements proved identical with those properties reported for artificially prepared Cu-thionein (see ref.[1]. The major absorption was in the far ultraviolet region with a weak shoulder at 270 nm attributable to copper charge-transfer transititions. 6 Cotton extrema were seen at 213, 283 and 302 nm (negative) and 245, 328 and 359 nm (positive). The possible role of Cu-thionein as an electron transport system was discussed.
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PMID:A naturally occurring Cu-thionein in Saccharomyces cerevisiae. 110 11

Chlorophyllin (CHL), a copper/sodium salt of chlorophyll used in the treatment of geriatric patients, is an anti-mutagen that has been demonstrated to inhibit carcinogen--DNA binding in vivo. To study the mechanism of inhibition, the microsomal metabolism of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and the kinetics of IQ--DNA binding were investigated in the presence and absence of CHL. In time-course studies, CHL produced greater than 80% inhibition of IQ--DNA binding and blocked the metabolism of IQ, such that 80% of the initial dose of carcinogen was recovered unmetabolized from the incubations after 1 h. Kinetic constants were determined for the in vitro DNA binding reaction, with the reaction rate measured as 'pmol IQ bound/mg DNA/min/mg microsomal protein'. Without altering V(max), the Km of the IQ--DNA binding reaction was increased by CHL, and the replot of Km/V(max) versus CHL concentration yielded a straight line with an inhibitor constant of 58.3 microM CHL. Spectrophotometric studies provided evidence in vitro for the formation of a non-covalent complex between CHL and IQ. The CHL--IQ complex had a stoichiometric ratio of 2:1 (mole ratio method) and an apparent dissociation constant from the Benesi-Hilderbrand plot of 1.41 x 10(-4)M at pH 7.4. These results are discussed in the context of a CHL inhibitory mechanism involving enzyme inhibition and molecular complex formation.
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PMID:Inhibition of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ)-DNA binding by chlorophyllin: studies of enzyme inhibition and molecular complex formation. 163 77

ESR studies of two copper(II) complexes of substituted dibenzotetraaza [14]annulenes, CuL and CuLA, in dimyristoylphosphatidylcholine (DMPC) and egg yolk phosphatidylcholine (EYPC) are reported. Our data show that both complexes partition into the membranes and that the rotational motion of CuL is faster than CuLA. Analysis of the ESR spectra of these complexes in DMPC vesicles indicate that the Cu-motion parameter, which is a measure of the degree of resolution of the nitrogen hyperfine structure, changes abruptly at the main phase transition. At 1 mole %, both complexes lowered the fluid/gel phase transition temperature by 2 degrees C as measured by the Cu-motion parameter. A gradual change of the Cu-motion parameter is observed in EYPC liposomes over the same temperature range. ESR spectra of both CuL and CuLA in oriented membranes reveal that both complexes are well oriented with the plane of the complex perpendicular to the bilayer surface.
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PMID:Orientational and motional properties of copper (II) complexes of dibenzotetraaza [14]annulenes in lipid bilayers: an ESR study. 166 72

Acetylcholinesterase (EC 3.1.1.7) activity was demonstrated in whole worm homogenates of adult Ascaridia galli with acetylthiocholine as substrate. The pH optimum was not measurable because of an autohydrolysis of the substrate. The Michaelis constant (Km) was 4 mM with saturation by excess substrate. Optimum enzyme activity was noted at a protein concentration of 200 mg/ml assay medium and at a temperature of 37 degrees C. Arrhenius plot of temperature dependence of the enzyme activity showed an energy of activation (delta Ea) of 28.962 K joule/mole above, and 25.448 K joule/mole below, the transition temperature (37 degrees C). Complete inhibition by eserine (physostigmine), a specific and classical acetylcholinesterase inhibitor, established the identity of the enzyme. A marginally higher enzyme activity was observed in females than in males as well as in homogenates from worms of mixed sexes. The enzyme was markedly activated by divalent metal cations such as Fe2+, Mg2+, Cd2+, Cu2+, Zn2+ and Ca2+, while Co2+ and Mn2+ inhibited the activity. Piperazine adipate at a concentration of 10(-3) M caused 45.5% and albendazole, a benzimidazole anthelmintic, 37.5% inhibition in the enzyme activity, while levamisole and mebendazole proved to be practically ineffective, causing an inhibition of 12 and 9%, respectively.
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PMID:Study of the acetylcholinesterase activity of Ascaridia galli: kinetic properties and the effect of anthelmintics. 178 36

The present article considers several physicochemical aspects of the complexation reaction of sodium amoxicillin and Cu(II) ion in a methanolic medium. Analysis of spectrophotometric data demonstrated the formation of two complex species with amoxicillin:Cu(II) ion mole ratios of 1:1 and 2:1. Stability constants (beta) and molar absorptivities at 610 nm (epsilon) of the complexes (20 degrees C) in methanol were calculated simultaneously by a computer program on the basis of absorbance data obtained at 610 nm. The values thus calculated for the 1:1 complex were as follows: log beta 1 = 5.48 +/- 0.21 L.mol-1, epsilon 1 = 70 +/- 2 L.mol-1.cm-1. The values for the 2:1 complex were as follows: log beta 2 = 8.98 +/- 0.17 L2.mol-2 and epsilon 2 = 138 +/- 4 L.mol-1.cm-1. The amoxicillin:Cu(II) ion complexes were quite stable over time.
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PMID:Reaction of sodium amoxicillin with Cu(II) ion in a methanolic medium. 180 Jul 18

Histochemical determinations of copper, zinc, and iron in intradermal pigmented nevi and melanomas revealed the presence of copper and iron in melanoma but not in nevi. Zinc was not detected in either melanomas or nevi. However, melanin was removed from the tissues prior to staining; therefore, it is possible that zinc was also removed by the procedure. Although the function of copper and iron in the melanoma cell is not known, they may be components of abnormal enzymes.
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PMID:Histochemical determinations of copper, zinc, and iron in pigmented nevi and melanoma. 151 Feb 28

The binding of Cd(II) and Zn(II) to human serum albumin (HSA) and dog serum albumin (DSA) has been studied by equilibrium dialysis and 113Cd(II)-NMR techniques at physiological pH. Scatchard analysis of the equilibrium dialysis data indicate the presence of at least two classes of binding sites for Cd(II) and Zn(II). On analysis of the high-affinity class of sites, HSA is shown to bind 2.08 +/- 0.09 (log K = 5.3 +/- 0.6) and 1.07 +/- 0.12 (log K = 6.4 +/- 0.8) moles of Cd(II) and Zn(II) per mole of protein, respectively. DSA bound 2.02 +/- 0.19 (log K = 5.1 +/- 0.8), and 1.06 +/- 0.15 (log K = 6.0 +/- 0.2) moles of Cd(II) and Zn(II) per mole of protein, respectively. Competition studies indicate the presence of one high-affinity Cd(II) site on both HSA and DSA that is not affected by Zn(II) or Cu(II), and one high-affinity Zn(II) site on both HSA and DSA that is not affected by Cd(II) or Cu(II). 113Cadmium-HSA spectra display three resonances corresponding to three different sites of complexation. In site I, Cd(II) is most probably coordinated to two or three histidyl residues, site II to one histidyl residue and three oxygen ligands (carboxylate), while for the most upfield site III, four oxygens are likely to be involved in the binding of the metal ion. The 113Cd(II)-DSA spectra display only two resonances corresponding to two different sites of complexation. The environment around Cd(II) at sites I and II on DSA is similar to sites I and II, respectively, on HSA. No additional resonances are observed in any of these experiments and in particular in the low field region where sulfur coordination occurs. Overall, our results are consistent with the proposal that the physiologically important high-affinity Zn(II) and Cd(II) binding sites of albumins are located not at the Cu(II)-specific NH2-terminal site, but at internal sites, involving mostly nitrogen and oxygen ligands and no sulphur ligand.
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PMID:Binding of cadmium(II) and zinc(II) to human and dog serum albumins. An equilibrium dialysis and 113Cd-NMR study. 181 86

The urinary excretion of chromium, copper and manganese was determined in 185 diabetics and in an equal number of control subjects by measuring the concentration of each of these metals using electrothermal atomic spectrophotometry and dividing the values by the urinary concentration of creatinine (creat) in each subject. The mean (SEM) values for the overall diabetics and the control group were 2.32 (0.17) and 2.62 (0.22) mumol Cr/mole of creat, 76.5 (5.5) and 73.9 (6.1) mumol Cu/mole of creat, and 3.56 (0.44) and 2.66 (0.3) mumol Mn/mole of creat, respectively. There was no correlation between the urinary excretion of any of the metals examined and age or sex of either group. While the cardiovascular or ophthalmologic diseases associated with diabetes did not influence the excretion of any of these metals, significantly higher urinary excretion of Cu was exhibited by diabetics with neuropathy (p < 0.0027) or infections (p < 0.014) than by those without. Also, diabetics with liver disorders or those who were not treated with insulin excreted significantly more Mn than did their diabetic counterparts.
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PMID:Urinary excretion of chromium, copper, and manganese in diabetes mellitus and associated disorders. 184 23

An allergen from Phleum pratense (timothy) pollen, Phl p V, has been isolated by a combination of copper chelate affinity chromatography and ion exchange chromatography. Phl p V binds IgE from serum of grass-sensitized donors as revealed in immunoelectrophoretic techniques and in SDS-PAGE immunoblot, and luminescence immunoassay (LIA) inhibition experiments indicate that the allergen represents a significant part of the IgE binding capacity of the extract. In immunoelectrophoresis, Phl p V is revealed as a single precipitate. However, molecular weight studies show that Phl p V consists of at least two isoforms with similar immunochemical properties, but with different molecular size. After SDS-PAGE treatment purified Phl p V is identified as two IgE-binding components, Phl p Va and Phl p Vb, with molecular weights 33 and 29 kD. After HPLC gel filtration, Phl p Va and Phl p Vb are identified in the major 30-kD eluate. After Sephadex G75 gel filtration of whole pollen extract, Phl p V is identified in fractions corresponding to molecular weights 47 and 25 kD. The 47-kD fraction corresponds to Phl p Va/Phl p Vb as seen in SDS-PAGE, while the 25-kD component presumably corresponds to a degradation product present in whole pollen extract. The NH2-terminal sequence of Phl p V, corresponding to approximately 10% of the molecule, has been determined. The sequence shows minor variations in some residues and contains besides many alanine residues also hydroxyproline; the sequence reveals no homologies to any known NH2 terminal sequence of other proteins. The amino acid composition, revealing 26 mole % alanine and no cysteine, does not show any similarities to other known amino acid compositions of allergens. From the amino acid composition determination and an immunoelectrophoretic comparison, Phl p V is estimated to represent 6% (w/w) of the whole pollen extract.
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PMID:Group V allergens in grass pollens. I. Purification and characterization of the group V allergen from Phleum pratense pollen, Phl p V. 186 92


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