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121.
Myeloperoxidase-catalyzed inactivation of alpha 1-protease inhibitor by human neutrophils 总被引:18,自引:0,他引:18
R A Clark P J Stone A El Hag J D Calore C Franzblau 《The Journal of biological chemistry》1981,256(7):3348-3353
We have examined the effect of the myeloperoxidase-hydrogen peroxide-halide system and of activated human neutrophils on the ability of serum alpha 1-protease inhibitor (alpha 1-PI) to bind and inhibit porcine pancreatic elastase. Exposure to the isolated myeloperoxidase system resulted in nearly complete inactivation of alpha 1-PI. Inactivation was rapid (10 to 20 s); required active myeloperoxidase, micromolar concentrations of H2O2 (or glucose oxidase as a peroxide generator), and a halide cofactor (Cl- or I-); and was blocked by azide, cyanide, and catalase. Intact neutrophils similarly inactivated alpha 1-PI over the course of 5 to 10 min. Inactivation required the neutrophils, a halide (Cl-), and a phorbol ester to activate secretory and metabolic activity. It was inhibited by azide, cyanide, and catalase, but not by superoxide dismutase. Neutrophils with absent myeloperoxidase or impaired oxidative metabolism (chronic granulomatous disease) failed to inactivate alpha 1-PI, and these defects were specifically corrected by the addition of myeloperoxidase or H2O2, respectively. Thus, stimulated neutrophils secrete myeloperoxidase and H2O2 which combine with a halide to inactivate alpha 1-PI. We suggest that leukocyte-derived oxidants, especially the myeloperoxidase system, may contribute to proteolytic tissue injury, for example in elastase-induced pulmonary emphysema, by oxidative inactivation of protective antiproteases. 相似文献
122.
Treatment of 2,3,6-trideoxy-1,4-di-O-(p-nitrobenzoyl)-3-(trifluoroacetamido)-l-lyxo-hexopyranose (1) with benzyl 2,3-dideoxy-d-glycero-pentopyranoside and p-toluenesulfonic acid gave a mixture of benzyl 2,3,6-trideoxy-4-O-p-nitrobenzoyl-3- (trifluoroacetamido)-l-lyxo-hexopyranoside (49%) and benzyl 2,3-dideoxy-4-O-[2,3,6-trideoxy-4-O-(p-nitrobenzoyl)-3-(trifluoroacetamido)-α-l-lyxo-hexopyranosyl]-d-glycero-pentopyranoside (4, 20 %). The structure of the disaccharide 4 was confirmed by a detailed, mass-spectrometric analysis in three modes, namely, negative- and positive-ion, chemical ionization, and electron impact. Similar treatment of the bis(p-nitrobenzoate) 1 with ethyl 2,3-dideoxy-d-glycero-pentopyranoside gave the ethyl glycoside and the desired disaccharide, showing that the transglycosylation is not restricted to benzyl glycosides. Removal of the p-nitrobenzoyl and the benzyl groups from 4 gave the disaccharide 2,3-dideoxy-4-O-(2,3,6-trideoxy-3-trifluoroacetamido-α-l-lyxo-hexopyranosyl)-d-glycero-pentopyranose. 相似文献
123.
The 13C.n.m.r spectra of water-soluble and -insoluble glucans synthesized by enzymes isolated from six strains of Streptococcus mutans are interpreted. The glucans are shown to be composed primarily of α(1→3)- and α-(1→6)-linked glucosyl residues, and the relative abundance of each linkage is estimated from peak areas. Treatment of water-insoluble glucans with dextranase is found to result in water-soluble and -insoluble products, the former enriched in α-(1→6)-linkages and the latter in α-(1→3)-linkages. The structural conclusions arrived at by 13C-n.m.r. spectroscopy are consistent with data from methylation analysis and 1H-n.m.r. spectroscopy. 相似文献
124.
The stability constants of the ternary Cu(II), Ni(II), and Co(II) complexes containing pyridoxamine (PM) and as a second ligand (L) glycine, DL-alanine, DL-valine, and β-phenylalnine were determined by pH-metric titration in 0.50 M KNO3 at 30°C. The corresponding constants of the equilibrium,
log X, are greater than would be expected for purely statistical reasons (log X = 0.6), except for few complex cases of Co(II). It has been also concluded that amino acids compete more than pyridoxamine for Ni(II) and Co(II) through the formation of 1:2:1:0 species rather than 2:1:1:0 of PM−:L−:M2+:H+. 相似文献
125.
Alcohol dehydrogenase was prepared from 2-day germinating maize and 3-day germinating broad-bean seeds by ammonium sulphate fractionation of sodium phosphate extracts, chromatography onDEAE cellulose and Sephadex G-200. The activity of the broad beanADH amounted to182 800 units per mg protein, that of maizeADH 79 000 units per mg protein. Besides oxidation of a series of alcohols at pH optimum in the alkaline region and with KM equalling 10-2M, alcohol dehydrogenases isolated from both plants catalyze the reduction of acetaldehyde, n-propanal, n-butanal, isobutanal and crotonal at pH optimum in the neutral region with KM equalling 10-3M. The inhibition studies using fatty acids and chloride ions revealed that the oxidation of alcohols is inhibited competitively by both types of inhibitors, with inhibition constants of 10-2M and 10-1M, respectively. The inhibition in the presence of acetaldehyde is non-competitive since the inhibitors do not compete with acetaldehyde and do not form an enzyme-NADH-inhibitor complex, yet they obviously react with the enzyme-NAD product only, thus giving rise to an enzyme-NAD-inhibitor complex. These differences in the behaviour of inhibitors may be interpreted in the sense that the binding sites of ethanol and acetaldehyde as substrates for broad bean and maize alcohol dehydrogenases are non equivalent. The nonequivalency discussed in the text. 相似文献
126.
The 1-methyl derivatives (3 and 4) of 3-(1-phenyl- (1) and 3-(1-p-bromophenylhydrazono-L-threo-2,3,4-trihydroxybutyl)-2-quinoxalinone (2) were prepared by methylation. Periodate oxidation of 3 gave 1-methyl-3-[1-(phenylhydrazono)glyoxal-1-yl]-2-quinoxalinone (5), which, on reduction with sodium borohydride, gave the corresponding 3-[2-hydroxy-1-(phenylhydrazono)ethyl] derivative (8). Reaction of 5 with hydroxylamine or benzoylhydrazine gave the corresponding 2-oxime (6) and 2-(benzoylhydrazone) (7), respectively. Acetic anhydride causes one molecule of 3 or 4 to undergo elimination of two molecules of water, with simultaneous acetylation and ring closure to afford pyrazoles 9 and 10, respectively. Pyrolysis of the triacetate of 3 led to the elimination of acetic acid from the sugar and the hydrazone residue, to give the 3-[5-(acetoxymethyl)-1-phenylpyrazol-3-yl] derivatives (9). Acetic acid was found to effect the same rearrangement, but without acetylation, of 1, 2, and 3 to give the 3-[5-(hydroxymethyl)] derivatives 11, 12, and 13, respectively. The structure of these pyrazoles was confirmed by a series of reactions, including methylation and acetylation. The n.m.r. and i.r. spectra of the compounds were investigated. 相似文献
127.
Condensation of 4,6-di-O-acetyl-2,3-O-carbonyl-α-d-mannopyranosyl bromide with benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-α-d-glucopyranoside (2) gave an α-d-linked disaccharide, further transformed by removal of the carbonyl and benzylidene groups and acetylation into the previously reported benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl)-α-d-glucopyranoside. Condensation of 3,4,6-tri-O-benzyl-1,2-O-(1-ethoxyethylidene)-α-d-glucopyranose or 2-O-acetyl-3,4,6-tri-O-benzyl-α-d-glucopyranosyl bromide with 2 gave benzyl 2-acetamido-3-O-(2-O-acetyl-3,4,6-tri-O-benzyl-β-d-glucopyranosyl)-4,6-O-benzylidene-2-deoxy-α-d-glucopyranoside. Removal of the acetyl group at O-2, followed by oxidation with acetic anhydride-dimethyl sulfoxide, gave the β-d-arabino-hexosid-2-ulose 14. Reduction with sodium borohydride, and removal of the protective groups, gave 2-acetamido-2-deoxy-3-O-β-d-mannopyranosyl-d-glucose, which was characterized as the heptaacetate. The anomeric configuration of the glycosidic linkage was ascertained by comparison with the α-d-linked analog. 相似文献
128.
129.
Injections of urine of patients with bladder cancer linked with bilharziasis, simple urinary bilharziasis, ascariasis or ancylostomiasis, induced cyst formation found in Opalina sudafricana when injected into its host Bufo regularis. It is suggested that the carcinogenic tryptophan metabolites present in the injected urine reach the parasites in the recta of the experimental toads and stimulate them to divide mitotically to form small forms which eventually encyst. This test may be of a diagnostic help in detecting any abnormality in tryptophan metabolism in some human patients. 相似文献
130.