STEREOCHEMICAL EVIDENCE FOR EVOLUTION OF PYRIDOXAL-PHOSPHATE ENZYMES OF VARIOUS FUNCTION FROM A COMMON ANCESTOR
STEREOCHEMICAL EVIDENCE FOR EVOLUTION OF PYRIDOXAL-PHOSPHATE ENZYMES OF VARIOUS FUNCTION FROM A COMMON ANCESTOR
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DOI：
10.1073/pnas.71.10.3888
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发表时间：
1974-01-01
影响因子：
11.1
通讯作者：
VOET, JG
中科院分区：
文献类型：
--
作者：
DUNATHAN, HC;VOET, JG
几种依赖于磷酸吡哆醛的酶可以将结合的辅因子转化为磷酸吡哆胺。这种转化可能是正常催化序列的必需部分，就像转氨酶一样，也可能是使酶失活的异常途径。这种转化需要辅因子的C4‘碳的质子化，现在已经证明这是在七种完全不同的吡哆醛-磷酸酶中以相同的绝对立体化学方式进行的。我们报道了其中之一，色氨酸合成酶B蛋白。质子化立体化学中的这种规律性表明辅因子与脱辅酶结合的几何构型具有显著的规律性。这种规律性被解释为整个酶家族从一个共同的前体进化而来的证据，在进化过程中，如果不经过催化不活跃的构象，就无法逆转其原始的、任意的结合立体化学。
Several pyridoxal-phosphate-dependent enzymes can convert the bound cofactor to pyridoxamine phosphate. This conversion may be an obligatory part of the normal catalytic sequence, as with transaminases, or may be an abnormal path, inactivating the enzyme. This conversion requires protonation of the C4′ carbon of the cofactor, which has now been shown to proceed stereospecifically andwith the same absolute stereochemistryin seven quite different pyridoxal-phosphate enzymes. We report on one of these, tryptophan synthase B protein. This regularity in protonation stereochemistry suggests a remarkable regularity in the geometry of cofactor binding to the apoenzyme. This regularity is interpreted as evidence for the evolution of this entire family of enzymes from a common progenitor which, through the course of evolution, could not invert its original, arbitrary binding stereochemistry without passing through catalytically inactive conformations.