F. Kurosaki et M. Arisawa, Free CoA as activator of 6-hydroxymellein synthase, a multifunctional polyketide biosynthetic enzyme in carrot, PHYTOCHEM, 50(4), 1999, pp. 565-569
The activity of 6-hydroxymellein (6HM) synthase, a multifunctional polyketi
de biosynthetic enzyme in carrot, was appreciably inhibited in the presence
of ATP: citrate lyase, a CoA-scavenging enzyme. Catalytic rate of the synt
hase markedly decreased when deuterium-labeled NADPH was employed in the en
zyme reaction, however, the isotope effect was appreciably reduced by the a
ddition of free CoA. These observations suggest that CoA is the activator o
f 6HM synthase both in low and high concentrations, and the compound functi
ons as the acyl acceptor for proper entry of the substrates and enhances th
e ketoreducing reaction, the rate limiting step of 6HM biosynthesis. (C) 19
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