Presence of Acetyl-CoA Synthetase in Ripened Bananas

Abstract

Acetyl-CoA synthetase (ACS) activity in fully ripened bananas was determined by HPLC. The ACS activity was higher for acetate as a substrate than for butyrate. The higher substrate specificity for acetate than for butyrate evidences that banana produces a great amount of acetate esters and a less amount of butyrate esters. The K. for MgCl2 for butyryl-CoA formation was 5-fold higher than that for acetyl-CoA formation. ACS activity was assayed in mitochondrial, microsomal, and cytosol fractions isolated from ripened banana pulp and the highest total enzyme activity was detected in the cytosol fraction. This is the first report on the presence of this enzyme, ACS, in fruit pulp.

Functional Characteristics of Aldehyde Dehydrogenase and Its Involvement in Aromatic Volatile Biosynthesis in Postharvest Banana Ripening

“…Many enzymes regarding the conversions between volatile alcohols, aldehydes/ketones, acids, and esters have been studied extensively in fruits and plants, and/or adapted from microorganism studies [8][9][10]. In banana fruit ripening, gene expression and enzyme activity of alcohol dehydrogenase (ADH, short and medium chains), which facilitates the interconversion between alcohols to aldehydes [11,12], acyl-CoA synthetase (ACS), which activates carboxylic acids to acyl-CoAs [13] thus can be used to biosynthesize esters, and alcohol acetyl transferase (AAT), which catalyzes ester biosynthesis, have been intensively studied (Figure 1) [14][15][16][17]. ALDH dehydrogenizes aldehydes to carboxylic acids in different plant tissues [1,18].…”

“…The purpose of the current study was to determine the enzyme which converts volatile straight and branched aldehydes to carboxylic acids, to identify their involvement in Beekwilder, Alvarez-Huerta et al [16] showed that when incubating petunia leaves with 3-methylbutanol vapor for 24 h, 3-methylbutyl 3-methylbutanoate was the dominant volatile, in addition to 3-methylbutanol in the headspace, indicating a strong dehydrogenization of 3-methylbutanol to 3-methylbutanal, further to 3-methylbutanoic acid, then passing through 3-methylbutanoyl-CoA, and finally synthesizing 3-methylbutyl 3methylbutanoate, catalyzed by ADH, ALDH, ACS, and AAT, respectively [13][14][15][16].…”