黑色素对酪氨酸羟化酶和苯丙氨酸羟化酶的影响。

Effects of melanin on tyrosine hydroxylase and phenylalanine hydroxylase.

作者信息

Nagatsu T, Numata(Sudo) Y, Kato T, Sugiyama K, Akino M

出版信息

Biochim Biophys Acta. 1978 Mar 14;523(1):47-52. doi: 10.1016/0005-2744(78)90007-4.

Abstract

Melanin inhibited rat liver phenylalanine hydroxylase, but activated tyrosine hydroxylase from rat brain (caudate nucleus), rat adrenal glands, and bovine adrenal medulla. Activation of tyrosine hydroxylase by melanin was demonstrated with the extensively dialyzed enzyme and in suboptimal concentrations of the substrate (tyrosine) and the cofactor (6-methyltetrahydropterin). Tyrosine hydroxylase from rat brain was activated by melanin more markedly than that from rat adrenal glands. Purified and extensively dialyzed bovine adrenal tyrosine hydroxylase had two Km values with 6-methyltetrahydropterin, depending upon its concentrations, but the melanin-activated tyrosine hydroxylase had a single Km value and showed the classical Michaelis-Menten kinetics.

摘要

黑色素抑制大鼠肝脏苯丙氨酸羟化酶，但激活大鼠脑（尾状核）、大鼠肾上腺以及牛肾上腺髓质中的酪氨酸羟化酶。黑色素对酪氨酸羟化酶的激活作用在经过充分透析的酶以及底物（酪氨酸）和辅因子（6-甲基四氢蝶呤）处于次优浓度的情况下得到了证实。大鼠脑内的酪氨酸羟化酶比大鼠肾上腺中的酪氨酸羟化酶更显著地被黑色素激活。纯化并经过充分透析的牛肾上腺酪氨酸羟化酶对于6-甲基四氢蝶呤有两个Km值（取决于其浓度），但黑色素激活的酪氨酸羟化酶有单一的Km值，并呈现出典型的米氏动力学。