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首页> 外文期刊>Critical Reviews in Biochemistry and Molecular Biology >Structural and functional comparison of polysaccharide-degrading enzymes [Review]
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Structural and functional comparison of polysaccharide-degrading enzymes [Review]

机译：多糖降解酶的结构和功能比较[综述]

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摘要

Sugar molecules as well as enzymes degrading them are ubiquitously present in physiological systems, especially for vertebrates. Polysaccharides have at least two aspects to their function, one due to their mechanical properties and the second one involves multiple regulatory processes or interactions between molecules, cells, or extracellular space. Various bacteria exert exogenous pressures on their host organism to diversity glycans and their structures in order for the host organism to evade the destructive function of such microbes. Many bacterial organism produce glycan-degrading enzymes in order to facilitate their invasion of host tissues. Such polysaccharide degrading enzymes utilize mainly two modes of polysaccharide-degradation, a hydrolysis and a beta-elimination process. The three-dimensional structures of several of these enzymes have been elucidated recently using X-ray crystallography. There are many common structural motifs among these enzymes, mainly the presence of an elongated cleft transversing these molecules which functions as a polysaccharide substrate binding site as well as the catalytic site for these enzymes. The detailed structural information obtained about these enzymes allowed formulation of proposed mechanisms of their action. The polysaccharide lyases utilize a proton acceptance and donation mechanism (PAD), whereas polysaccharide hydrolases use a direct double displacement (DD) mechanism to degrade their substrates. [References: 119]
机译：糖分子以及降解它们的酶普遍存在于生理系统中，特别是对于脊椎动物而言。多糖的功能至少有两个方面，一方面是由于其机械性能，另一方面则涉及多个调节过程或分子，细胞或细胞外空间之间的相互作用。为了使宿主生物逃避这种微生物的破坏性作用，各种细菌在其宿主生物上施加外源压力以使聚糖及其结构多样化。许多细菌有机体会产生降解聚糖的酶，以促进它们入侵宿主组织。这样的多糖降解酶主要利用多糖降解的两种模式，即水解和β-消除过程。最近已经使用X射线晶体学阐明了其中几种酶的三维结构。这些酶中有许多常见的结构基序，主要是存在横穿这些分子的细长裂缝，这些裂缝起着多糖底物结合位点以及这些酶的催化位点的作用。获得的有关这些酶的详细结构信息允许制定其作用机制。多糖裂解酶利用质子接受和捐赠机制（PAD），而多糖水解酶利用直接双置换（DD）机制降解其底物。 [参考：119]

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