Lysine241 of tyrosine hydroxylase is not required for binding of tetrahydrobiopterin substrate.
Lysine241 of tyrosine hydroxylase is not required for binding of tetrahydrobiopterin substrate.
复制标题
四氢生物蝶呤底物的结合不需要酪氨酸羟化酶的赖氨酸 241。
DOI：
10.1006/abbi.1993.1239
复制
发表时间：
1993
影响因子：
3.9
通讯作者：
Fitzpatrick,PF
中科院分区：
文献类型：
--
作者：
Daubner,SC;Fitzpatrick,PF
苯丙氨酸羟化酶中194和198位的赖氨酸残基已显示与作为苯基四氢蝶呤类似物的光亲和标记反应（Gibbs，B. S.，和Benkovic，S. J.（1991）Biochemistry 30，6795-6802），以表明这些赖氨酸残基参与四氢生物蝶呤结合的方式。相关酶酪氨酸羟化酶在241位具有赖氨酸，鉴于其C-末端330个氨基酸与苯丙氨酸羟化酶的氨基酸之间75%的同一性，该赖氨酸对应于苯丙氨酸羟化酶的赖氨酸194。用定点突变法将酪氨酸羟化酶的赖氨酸241突变为丙氨酸。稳态动力学参数测定野生型和K241 A酪氨酸羟化酶。野生型和K241 A酶之间没有动力学参数差异，包括Vmax值，四氢生物蝶呤，6-甲基-四氢蝶呤和酪氨酸的米氏常数，以及去甲肾上腺素的抑制常数。这些结果表明赖氨酸241对于四氢生物蝶呤与酪氨酸羟化酶的结合不是必需的。
The lysine residues at positions 194 and 198 in phenylalanine hydroxylase have been shown to react with a photoaffinity label which is an analog of phenyltetrahydropterin (Gibbs, B. S., and Benkovic, S. J. (1991)Biochemistry30, 6795-6802), in a manner suggesting that these lysine residues are involved in tetrahydrobiopterin binding. The related enzyme tyrosine hydroxylase has a lysine at position 241 which, given the 75% identity between its C-terminal 330 amino acids and those of phenylalanine hydroxylase, corresponds to lysinel94 of phenylalanine hydroxylase. Site-directed mutagenesis was used to alter lysine241 of tyrosine bydroxylase to alanine. Steady-state kinetic parameters were measured for wild-type and K241A tyrosine bydroxylase. No kinetic parameter differed between the wild-type and K241A enzymes, includingVmaxvalues, Michaelis constants for tetrahydrobiopterin, 6-methyl-tetrahydropterin, and tyrosine, and the inhibition constants for norepinephrine. These results show that lysine241 is not required for tetrahydrobiopterin binding to tyrosine hydroxylase.