Effects of phosphorylation on binding of catecholamines to tyrosine hydroxylase: specificity and thermodynamics.
Effects of phosphorylation on binding of catecholamines to tyrosine hydroxylase: specificity and thermodynamics.
复制标题
磷酸化对儿茶酚胺与酪氨酸羟化酶结合的影响：特异性和热力学。
DOI：
10.1021/bi991901r
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发表时间：
2000
期刊：
影响因子：
2.9
通讯作者：
Fitzpatrick,PF
中科院分区：
文献类型：
--
作者：
Ramsey,AJ;Fitzpatrick,PF
作为儿茶酚胺类神经递质生物合成中限速步骤的催化剂，酪氨酸羟化酶的活性受到严格调节。翻译后调节的主要手段是N-末端调节结构域中丝氨酸残基的可逆磷酸化。丝氨酸40的磷酸化已显示对多巴胺解离的速率常数具有大的影响，而对DOPA解离的速率常数具有小得多的影响[Ramsey，A. J.，和菲茨帕特里克，P. F.（1998）Biochemistry37，8980 - 8986]。为了确定亲和力差异的结构基础，并进一步测试先前提出的调节模型的有效性，已经确定了丝氨酸40的磷酸化对一系列儿茶酚的亲和力的影响。由于解离速率的差异，未磷酸化酶的亲和力变化3个数量级。最高的亲和力被发现与缺乏羧酸根的儿茶酚胺。磷酸化酶的亲和力显示出小得多的范围。在结合二羟基苯丙氨酸的情况下，磷酸化后亲和力的降低主要是由于相互作用焓的降低。基于这些结果，提出了磷酸化作用的结构模型。
As the catalyst for the rate-limiting step in the biosynthesis of the catecholamine neurotransmitters, the activity of tyrosine hydroxylase is tightly regulated. A principle means of posttranslational regulation is reversible phosphorylation of serine residues in an N-terminal regulatory domain. Phosphorylation of serine 40 has been shown to have a large effect on the rate constant for dissociation of dopamine and a much smaller effect on that for DOPA [Ramsey, A. J., and Fitzpatrick, P. F. (1998)Biochemistry37, 8980−8986]. To determine the structural basis for the differences in affinity and to further test the validity of the previously proposed model for regulation, the effects of phosphorylation of serine 40 on the affinities for a series of catechols have been determined. The affinities of the unphosphorylated enzyme vary by 3 orders of magnitude due to differences in the rates of dissociation. The highest affinities are found with catecholamines which lack a carboxylate. The affinities of the phosphorylated enzyme show a much smaller range. In the case of binding of dihydroxyphenylalanine, the decrease in affinity upon phosphorylation is due primarily to a decrease in the enthalpy of the interaction. Based upon these results, a structural model for the effect of phosphorylation is proposed.