Bifunctional peptidylglcine alpha-amidating enzyme requires two copper atoms for maximum activity.
Bifunctional peptidylglcine alpha-amidating enzyme requires two copper atoms for maximum activity.
复制标题
双功能肽基甘氨酸α-酰胺化酶需要两个铜原子才能获得最大活性。
DOI：
10.1006/abbi.1994.1225
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发表时间：
1994
影响因子：
3.9
通讯作者：
Merkler,DJ
中科院分区：
文献类型：
--
作者：
Kulathila,R;Consalvo,AP;Fitzpatrick,PF;Freeman,JC;Snyder,LM;Villafranca,JJ;Merkler,DJ
C-末端甘氨酸延伸多肽转化为C-末端α-酰胺化肽有两个不同的反应，这两个反应都是由双功能的甘氨酸α-酰胺化酶催化的。第一步是C端甘氨酸残基的α-羟基化，第二步是α-羟基甘氨酸延伸肽的脱烷基，生成α-酰胺化肽和乙醛。结果表明，在较高的酶浓度(∼80μM)条件下，该双功能酶需要1.9±0.2摩尔的铜/摩尔酶才能达到最大的丹氨酰-酪氨酸-赖氨酸-甘氨酸酰胺化活性。纯化后的酶含有亚化学计量比的铜，并且只有微量的酰胺化活性。在最佳铜化学计量比下，外源铜(II)离子使∼的酰胺化活性增加3000倍，过量的铜(II)则抑制该酶的活性。二价金属离子：Mn(II)、Fe(II)、Ni(II)、Cd(II)和氧钒离子VO(II)的加入对酰胺化活性无刺激作用。酶催化的α-羟基马尿酸脱烷基制苯甲酰胺反应不依赖于铜，表明酰胺化反应对铜的依赖必须归因于多肽α-羟基化对铜的依赖。
The conversion of C-terminal glycine-extended peptides to C-terminal α-amidated peptides occurs in two distinct reactions, both of which are catalyzed by bifunctional peptidylglycine α-amidating enzyme. The first step is the α-hydroxylation of the C-terminal glycine residue and the second step is the dealkylation of the α-hydroxyglycine-extended peptide to the α-amidated peptide and glyoxylate. We show that the bifunctional enzyme requires 1.9 ± 0.2 mol of copper/mol of enzyme for maximal dansyl-Tyr-Lys-Gly amidation activity under the conditions of high enzyme concentration (∼80 μM) required to measure initial rates for this poor substrate. The enzyme, as purified, contains a substoichiometric amount of copper and has only trace levels of amidation activity. Addition of exogenous Cu(II) ions stimulates amidation activity ∼3000-fold at the optimum copper stoichiometry and the enzyme is then inhibited by excess Cu(II). No stimulation of amidation activity is observed upon the addition of the following divalent metal ions: Mn(II), Fe(II), NI(II), Cd(II), and the oxovanadium cation, VO(II). The enzyme-catalyzed dealkylation of α-hydroxyhippuric acid to benzamide shows no dependence on copper, indicating that the copper dependence of the amidation reaction must be attributed to a copper dependence in peptide α-hydroxylation.