4-hydroxycinnamoyl-CoA hydratase/lyase (HCHL) - An enzyme of phenylpropanoid chain cleavage from Pseudomonas

The enzyme 4-hydroxycinnamoyl-CoA hydratase/lyase (HCHL), which catalyzes a hydration and two-carbon cleavage step in the degradation of 4-hydroxycinn amic acids, has been purified and characterized from Pseudomonas fluorescen s strain AN103. The enzyme is a homodimer and is active with three closely related substrates, 4-coumaroyl-CoA, caffeoyl-CoA, and feruloyl-CoA (K-m va lues: 5.2, 1.6, and 2.4 mu M, respectively), but not with cinnamoyl-CoA or with sinapinoyl-CoA. The abundance of the enzyme reflects a low catalytic c enter activity (2.3 molecules s(-1) at 30 degrees C; 4-coumaroyl-CoA as sub strate). (C) 1999 Academic Press.