| 摘要 |
PURPOSE: To obtain the subject enzyme having activity to also catalyze the transformative reaction between a 2-oxocarboxylic acid and 2-hydroxycarboxylic acid, thus useful for diversification of substance transformation by enzymatic reaction. CONSTITUTION: This new malic acid enzyme with NAD or NADP as a coenzyme is obtained by culturing e.g. Streptococcus bovis ATCC 15352 as rumen microbe, having activity to reversibly catalyze the following reactions: (a) L-malic acid is transformed into pyruvic acid and CO2 ; (b) 2-oxoisovaleric acid is transformed into 2-hydroxyisovaleric acid; and (c) 2-oxoisocaproic acid is transformed into 2-hydroxyisocaproic acid, and having the following properties: (1) having an amino acid sequence of the formula in the N-terminal domain; (2) molecular weight: about 80000 under reducing condition, about 40000 under non-reducing condition, determined by SDS-PAGE; and (3) the reaction (a) needs divalent cations, being promoted by monovalent cations. |
