Spivey H O, Merz J M
Bioessays. 1989 Apr;10(4):127-30. doi: 10.1002/bies.950100409.
Evidence for the association of 'soluble' enzymes in vivo is extensive and compelling. These associations occur in all compartments of the cell of both prokaryotes and eukaryotes. Several factors present in vivo promote these associations among enzymes whose association in vitro is often too weak to detect. Several physiological advantages of the associated enzyme complexes can be identified, most (but not all) of which are the consequence of microcompartmentation of metabolites (substrate channeling). Substrate channeling of intermediates by either a 'direct transfer' process or 'proximity effects' can occur. The latter mechanism does not require the special molecular features needed for the direct transfer mechanism and may, therefore, exist in more general situations in the cell. Criticisms of these views are discussed. We argue that these criticisms have been largely answered by experiment and theory in recent years. Studies on simple systems in vitro, nevertheless, contribute important insights concerning the more complex phenomena in vivo.
“可溶性”酶在体内存在关联的证据广泛且有说服力。这些关联发生在原核生物和真核生物细胞的所有区室中。体内存在的几个因素促进了酶之间的这些关联，而这些酶在体外的关联往往太弱而无法检测到。可以确定相关酶复合物的几个生理优势，其中大多数（但不是全部）是代谢物微区室化（底物通道化）的结果。中间体的底物通道化可以通过“直接转移”过程或“邻近效应”发生。后一种机制不需要直接转移机制所需的特殊分子特征，因此可能存在于细胞中更普遍的情况。本文讨论了对这些观点的批评。我们认为近年来这些批评在很大程度上已通过实验和理论得到解答。然而，体外简单系统的研究为体内更复杂的现象提供了重要的见解。
