Studies on sulfhydryl groups of Aspergillus niger amine oxidase.
Amino acid analysis of the amine oxidase of Aspergillus niger (monoamine:O2 oxidoreductase (deaminating), EC 1.4.3.4) showed a composition similar to that of bovine plasma enzyme. One molecule of enzyme contained 25 Cys residues. It was shown that 9 to 11 residues of Cys were titrated to be SH groups. The amine oxidase reaction was markedly inhibited by metal ions (Cu2+, Hg2+, Ag+). The enzyme was inactivated with SH reagents (phenyl mercuric acetate, Cl-HgBzO-) and the extent of this inactivation was dependent on the time of incubation with SH reagents. Also, the Cl-HgBzO- -inactivated enzyme was reactivated with cysteine and this reactivation was biphasic with the time of incubation. The Cl-HgBzO--inactivated amine oxidase was compared with the native enzyme in their reactivity with phenylhydrazine and their spectral properties. The results showed that the Cl-HgBzO--inactivated enzyme had lower reactivity with phenylhydrazine than the native enzyme and had higher absorbance values than the native enzyme around 400 nm wavelengths.
D000596:Amino Acids / Q000032:analysis; D001230:Aspergillus / Q000201:enzymology*; D001234:Aspergillus niger / Q000201:enzymology*; D002241:Carbohydrates / Q000032:analysis; D002413:Cations, Divalent / Q000494:pharmacology; D007501:Iron / Q000494:pharmacology; D007700:Kinetics; D008995:Monoamine Oxidase / Q000032:analysis* / Q000378:metabolism; D011485:Protein Binding; D012834:Silver / Q000494:pharmacology; D013053:Spectrophotometry; D013438:Sulfhydryl Compounds / Q000032:analysis; D013439:Sulfhydryl Reagents / Q000494:pharmacology
D000596:Amino Acids; D002241:Carbohydrates; D002413:Cations, Divalent; D013438:Sulfhydryl Compounds; D013439:Sulfhydryl Reagents; D012834:Silver; D007501:Iron; D008995:Monoamine Oxidase