The 1 ml assay
contained 50 mM MOPS, pH 7.0, 1 mM DTT, 75 mM acetoacetyl-CoA
(Sigma), 0.15 mM NADH (Sigma) and 5 ml of purified enzyme. Assays
were carried out at 30 uC and absorbance at 340 nm was followed. The
initial rate of Hbd was calculated using an extinction coefficient of
6.22 mM21 cm21 for NADH. The Crt assay was a modification of a prior
protocol (Waterson & Hill, 1972).