Enzymatic Synthesis of a β-Hydroxy-β-methylglutaric Acid-derivative by a Cell-Free System from Sweet Potato with Black Rot

Abstract

When 1-C¹⁴-acetyl-CoA was incubated with an enzyme preparation obtained from the non-infected tissue adjacent to the infected region of sweet potato with black rot, a C¹⁴-labeled β-hydroxy-β-methylglutaric acid-derivative was synthesized. This was concluded from the fact that the main ethyl acetate-extractable substance after alkaline hydrolysis of the reaction products proved to be β-hydroxy-β-methylglutaric acid, as demonstrated by paper radiochromatography, paper radioautography and constancy of specific radioactivity through repeated crystallizations.
The slight enzymatic activities were detected in both healthy and cut tissues where furanoterpenoids did not occur. The activity was higher in the tissue after 2 days of infection than after 1 day in parallel with the accumulation of furanoterpenoids.
The enzymatic synthesis was localized both in microsomal and supernatant fractions. No essential cofactors have been detected for the reaction. Some sulfhydryl-blocking reagents strongly inhibited the enzymatic activity.