Department of Biochemistry, University of Cambridge, Tennis Court Road, CB2 1QW, Cambridge, UK.
Planta. 1976 Jan;130(3):283-90. doi: 10.1007/BF00387834.
Exogenous supplies of phenylalanne, cinnamic acid and p-coumaric acid can inhibit the appearance of phenylalanine ammonia-lyase (PAL, E.C. 4.3.1.5) activity in potato tuber discs, and exogenous supplies of cinnamic acid and p-coumaric acid can inhibit the appearance of cinnamic acid 4-hydroxylase (CA4H, E.C. 1.14.13.11) activity. The time-courses of the inhibitory effects of (a) exogenous phenylalanine on the appearance of PAL activity and (b) exogenous cinnamic acid on the appearance of CA4H activity suggest that the respective substrates of the two enzymes have no inhibitory effects per se, but rather that metabolic derivatives are the active agents. Accordingly, cinnamic acid and p-coumaric acid, but not phenylalanine can inhibit the initial appearance of PAL activity. Similarly, p-coumaric acid but not cinnamic acid can inhibit the initial appearance of CA4H activity. The inhibitory effects of exogenous cinnamic acid and p-coumaric acid on the initial appearance of PAL activity are independent. These findings are discussed in relation to the control in vivo of the levels of activity of PAL and CA4H.
外源性苯丙氨酸、肉桂酸和对香豆酸的供应可以抑制马铃薯块茎中苯丙氨酸解氨酶（PAL，EC 4.3.1.5）活性的出现，外源性肉桂酸和对香豆酸的供应可以抑制肉桂酸 4-羟化酶（CA4H，EC 1.14.13.11）活性的出现。（a）外源性苯丙氨酸对 PAL 活性出现的抑制作用和（b）外源性肉桂酸对 CA4H 活性出现的抑制作用的时间进程表明，两种酶的各自底物本身没有抑制作用，而是代谢衍生物是活性物质。因此，肉桂酸和对香豆酸，但不是苯丙氨酸，可以抑制 PAL 活性的初始出现。同样，对香豆酸而不是肉桂酸可以抑制 CA4H 活性的初始出现。外源性肉桂酸和对香豆酸对 PAL 活性初始出现的抑制作用是独立的。这些发现与体内控制 PAL 和 CA4H 活性水平的关系进行了讨论。
