Evidence for essential histidine residues in bovine-liver mitochondrial monoamine oxidase.
Ethoxyformic acid anhydride, amino-1H-tetrazole, and photooxidation in the presence of rose bengal, which are reagents known to react with histidine residues of proteins, were shown to inactivate monoamine oxidase. Ethoxyformic acid anhydride reacted with about 6 histidine residues per 100 000 g of protein under the experimental conditions adopted and completely inactivated the enzyme. However, NH2OH reactivated the ethaxyformic acid derivative t only. Since NH2OH specifically deacylates N-ethoxyformylimidazole, it was shown that at least some of the histidine residues are essential for activity. In addition, photooxidation experiments in the presence of 0.01% rose bengal confirmed that only histidine residues of bovine hepatic monoamine oxidase are destroyed under the designated experimental conditions. About 9 histidine residues per 100 000 g of protein were destroyed during the photooxidation experiments. In the presence of substrate, kynuramine or benzylamine, only 7 histidine residues were destroyed, which indicates that 2 histidine residues per 100 000 g of protein are essential for activity.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D005019:Ethyl Ethers / Q000494:pharmacology; D005182:Flavin-Adenine Dinucleotide / Q000032:analysis; D005561:Formates / Q000494:pharmacology; D006639:Histidine / Q000032:analysis; D007461:Iodoacetates / Q000494:pharmacology; D007700:Kinetics; D008930:Mitochondria, Liver / Q000201:enzymology*; D008995:Monoamine Oxidase / Q000032:analysis*; D010084:Oxidation-Reduction; D010777:Photochemistry; D011485:Protein Binding; D012395:Rose Bengal / Q000494:pharmacology; D013777:Tetrazoles / Q000494:pharmacology
D000596:Amino Acids; D005019:Ethyl Ethers; D005561:Formates; D007461:Iodoacetates; D013777:Tetrazoles; D005182:Flavin-Adenine Dinucleotide; D012395:Rose Bengal; D006639:Histidine; D008995:Monoamine Oxidase