Norio Shibamoto

Coriolus versicolor Laccase Catalyzes the Decarboxylation of 2-(4-Hydroxyphenyl)-glycine and 4-Hydroxymandelic Acid

Laccasc (benzenediol: oxygen oxidoreductase, EC 1.1O.3.2) has been found in some fungal strains belonging to various classes.i) The enzyme generally catalyzes the removal of hydrogen from phenolic hydroxyl groups or aromatic amino groups using molecular oxygcn as a primary electron acceptor to give radicals, which undergo free-radical additions and related reactions to give various products.2-s) During the investigation n a laccase from the fungus Coriolus versieotor, we found that the enzyme catalyzed the conversion of 2-(4-hydroxyphenyl)glycine (HPG) or 4hydroxyrnandelic acid (HMA) to 4-hydroxybenzaldehyde (HBA), which was a single product from either substrate and was not converted further. Laccase is known to remove

Colorimetric measurement of total activity of leucine aminopeptidase and arylamidase in serum using laccase-catalyzed oxidative decarboxylation

Abstract A simple colorimetric method for measuring the total activity of leucine aminopeptidase (EC 3.4.11.1) and arylamidase (EC 3.4.11.2) in serum was developed. The assay method is based on the following series of reactions; leucine aminopeptidase and arylamidase hydrolyze a substrate, l -leucyl- l -2-(4-hydroxyphenyl)glycine, to liberate 2-(4-hydroxyphenyl)glycine. The compound is then converted into 4-hydroxybenzaldehyde by laccase-catalyzed oxidative decarboxylation. Finally, the 4-hydroxybenzaldehyde produced is colorimetrically measured by treatment with 2,4-dinitrophenylhydrazine to evaluate the total activity of these aminopeptidases.

Colorimetric measurement of angiotensin I-converting enzyme activity using bilirubin oxidase-catalyzed oxidative decarboxylation

Abstract A simple colorimetric method for determining the activity of angiotensin I-converting enzyme (ACE) was developed. The assay method is based on the following series of reactions: ACE hydrolyzes a tripeptide substrate, N- benzoyl- l -2-(4-hydroxyphenyl)glycyl- l -histidyl- l -leucine to liberate N- benzoyl- l -2-(4-hydroxyphenyl)glycine . The compound is then converted into 4-hydroxybenzaldehyde (HBA) through oxidative decarboxylation catalyzed by bilirubin oxidase from Myrothecium verrucaria . Finally, HBA is measured colorimetrically by treatment with 2,4-dinitrophenylhydrazine to evaluate the activity of ACE. The optimum pH of ACE for the substrate was 8.3, and the K m value was 0.072 mM. The formation rate of HBA was proportional to the ACE concentration, and the correlation coefficient was 0.997.