Involved in the biosynthesis of volatile esters which confer ripe apple fruit flavor (PubMed:24661745, Ref.3). Alcohol acyl transferase that can use a wide range of alcohols as substrate, including 2-methylbutanol, hexanol and ethanol, to produce esters such as butyl butanoate, butyl hexanoate, hexyl butanoate, 2-methylbutyl acetate (2MBA), butyl acetate, hexyl acetate and 2-methylbutyl butanoate (2MBB), and, to some extent, ethyl butanoate and ethyl hexanoate (PubMed:24661745, PubMed:15955071). acetyl-CoA + butan-1-ol = butyl acetate + CoA acetyl-CoA + hexan-1-ol = CoA + hexyl acetate 2-methylbutan-1-ol + acetyl-CoA = 2-methylbutyl acetate + CoA butanoyl-CoA + hexan-1-ol = CoA + hexyl butanoate hexan-1-ol + hexanoyl-CoA = CoA + hexyl hexanoate 2-methylbutan-1-ol + butanoyl-CoA = 2-methylbutyl butanoate + CoA butan-1-ol + butanoyl-CoA = butyl butanoate + CoA butan-1-ol + hexanoyl-CoA = butyl hexanoate + CoA butanoyl-CoA + ethanol = CoA + ethyl butanoate ethanol + hexanoyl-CoA = CoA + ethyl hexanoate hexan-1-ol + octanoyl-CoA = CoA + hexyl octanoate 2-methylbutan-1-ol + hexanoyl-CoA = 2-methylbutyl hexanoate + CoA Repressed by metal ions, zinc ions having the strongest impact, and magnesium, cobalt, nickel, manganese and calcium ions acting as partial inhibitors (PubMed:15955071). Strongly inhibited by p-chloromercuribenzoic acid (PCMB) and, to a lower extent, by dithiothreitol (PubMed:15955071). Optimum pH is 7-9. Optimum temperature is 20-37 degrees Celsius. Highly expressed in the cortex and skin of ripe fruit. Accumulates progressively during fruit development. Slightly induced by ethylene. Reduction in total esters production but accumulation of precursor alcohols and aldehydes in ripening apple fruits, leading to modified aroma and flavor. The fruit of cv. Royal Gala exhibits a high ester accumulation, whereas the cv. Granny Smith contains low ester levels; this influences strongly the ripe apple fruit aroma. Belongs to the plant acyltransferase family. The intimacy of flavour - Issue 231 of December 2020