ROLE ALDONOLACTONASE IN CONVERSION OF L-GULONATE TO L-ASCORBATE
ROLE ALDONOLACTONASE IN CONVERSION OF L-GULONATE TO L-ASCORBATE
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DOI：
10.1016/0006-3002(61)90289-x
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发表时间：
1961-01-01
期刊：
影响因子：
--
通讯作者：
LEHNINGER, AL
中科院分区：
文献类型：
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作者：
BUBLITZ, C;LEHNINGER, AL
大鼠肝脏可溶性部分经等电沉淀和丙酮等电沉淀及热处理，再经羧甲基纤维素柱层析，可将大鼠肝脏可溶性部分的醛内酯酶纯化110倍，得率为34%。在酶的纯化过程中，醛内酯酶活性与大鼠肝微粒体中的L-古龙内酯氧化酶促进L-古龙内酯酶转化为L-抗坏血酸的活性呈基本恒定的比例关系。因此，该醛内酯酶被确定为在内酯氧化之前催化L-古龙酸内酯(反应a)(反应b)：L-古龙内酯L-古龙内酯+水(A)L-古龙内酯+1/2-O2-[前进箭头]L-抗坏血酸+水(B)。醛内酯酶能催化从游离的L-古罗酸盐中净积累平衡量的内酯。讨论了该酶的组织分布和底物专一性与不同物种合成L-抗坏血酸能力的关系。
Aldonolactonase of the soluble fraction of rat liver has been purified 110-fold in a yield of 34% by isoelectric precipitation and heat treatment in the presence of MN++ fractionation with acetone, and finally chromato-graphy on carboxymethylcellulose columns. During the purification of the enzyme, the aldonolactonase activity and the activity in stimulating conversion of L-gulonate to L-ascorbate by the L-gulonolactone oxidase of rat liver microsomes accompanied each other in an essential constant ratio. The aldonolactonase thus was identified as catalyzing the lactonization of L-gulonate (reaction a) prior to the oxidation of the lactone (reaction b): L-gulonateL-gulonolactone + H2O (a) L-gulonolactone + 1/2-O2-[forward arrow]L-ascorbate + H2O (b). Aldonolactonase was shown to catalyze the net accumulation of equilibrium quantities of lactone from free L-gulonate. The tissue distribution and substrate specificity of the enzyme are discussed in relation to the ability of various species to synthesize L-ascorbic acid.