ROLE OF ASCORBATE IN PROLYL HYDROXYLASE REACTION
ROLE OF ASCORBATE IN PROLYL HYDROXYLASE REACTION
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DOI：
10.1016/0006-291x(78)91010-0
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发表时间：
1978-01-01
影响因子：
3.1
通讯作者：
KIVIRIKKO, KI
中科院分区：
文献类型：
--
作者：
MYLLYLA, R;KUUTTISAVOLAINEN, ER;KIVIRIKKO, KI
2-氧戊二酸与纯脯氨酰羟化酶的结合不需要抗坏血酸，在没有抗坏血酸的情况下，该酶催化羟基化的最大速率为5-10秒，相当于15-30个反应周期。大约1分钟后，在没有抗坏血酸的情况下，反应速率很低，即使只有1 - 2%的游离二价铁被氧化。这些和其他数据表明，脯氨酸羟化酶可以在没有抗坏血酸的情况下催化许多反应循环，但在某些阶段，羟化作用停止，可能是由于酶结合铁的氧化，这时需要抗坏血酸作为一种相当特定的还原剂来重新激活酶。
Ascorbate was not required for the binding of 2-oxoglutarate to pure prolyl hydroxylase, and the enzyme catalyzed hydroxylation in the absence of ascorbate at an essentially maximal rate for 5–10 s, corresponding to 15–30 reaction cycles. After about one min the reaction rate in the absence of ascorbate was very low, even though only 1–2 % of the free bivalent iron had become oxidized. These and additional data indicate that prolyl hydroxylase can catalyze a number of reaction cycles without ascorbate, but at some stage the hydroxylation ceases, probably due to oxidation of the enzyme-bound iron, and ascorbate is then required as a quite specific reductant to re-activate the enzyme.