Enzymic Synthesis of Lignin Precursors

摘要: A cinnamoyl-coenzyme reductase catalyzing the NADPH-dependent reduction of substituted cinnamoyl-CoA thiol esters to corresponding cinnamaldehydes was isolated from cell suspension cultures soybean (Glycine max L. var. Mandarin). 1660-fold purification enzyme achieved by (NH4)2SO4 fractionation, chromatography on DEAE-cellulose, hydroxyapatite and Sephadex G-100 affinity 5′-AMP-Sepharose. The apparent molecular weight found be about 38000 basis elution volume a column. Maximum rate reaction observed between pH 6.0 6.2 in 0.1—0.2 M citrate buffer at 30 °C. markedly inhibited reagents. The showed high degree specificity for esters. Feruloyl-CoA substrate with lowest Km value (73 μM) highest V (230 nkat/mg) followed 5-hydroxyferuloyl-CoA, sinapoyl-CoA, p-coumaroyl-CoA, caffeoyl-CoA cinnamoyl-CoA. No took place acetyl-CoA. NADPH varied type substrate. values 28, 120, 290 pM were feruloyl-CoA, respectively. NADH only 5 % that NADPH. The products CoASH NADP+ reaction. Ki range 0.5—1 mM inhibition noncompetitive (mixed) type. role biosynthesis lignin precursors is discussed.