Demidkina T V, Myagkikh I V, Azhayev A V
Institute of Molecular Biology, USSR Academy of Sciences, Moscow.
Eur J Biochem. 1987 Dec 30;170(1-2):311-6. doi: 10.1111/j.1432-1033.1987.tb13701.x.
The interactions of tyrosine phenol-lyase with its substrates: L-tyrosine and L-serine, and the competitive inhibitors: L-alanine, L-phenylalanine, L-m-tyrosine, were studied. It was demonstrated that the enzyme catalyzed a half-transamination reaction between substrates or inhibitors and the protein-bound pyridoxal phosphate. The products of this side-reaction, pyridoxamine phosphate and the respective keto acids, were identified. The kinetic parameters were determined for beta-elimination of L-tyrosine and of L-serine, and for the transamination of L-serine and the inhibitors used. The transfer of the amino group to the coenzyme takes place in the direction from amino acid to pyridoxal phosphate, but not in the opposite direction, i.e. the transamination is irreversible.
研究了酪氨酸酚裂解酶与其底物L-酪氨酸和L-丝氨酸，以及竞争性抑制剂L-丙氨酸、L-苯丙氨酸、L-间酪氨酸之间的相互作用。结果表明，该酶催化底物或抑制剂与蛋白质结合的磷酸吡哆醛之间的半转氨反应。鉴定了该副反应的产物磷酸吡哆胺和相应的酮酸。测定了L-酪氨酸和L-丝氨酸β-消除反应以及L-丝氨酸与所用抑制剂转氨反应的动力学参数。氨基向辅酶的转移是从氨基酸到磷酸吡哆醛的方向进行的，而不是相反的方向，即转氨反应是不可逆的。
