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首页> 外文期刊>Journal of Molecular Biology >CARBOHYDRATE AND PROTEIN-BASED INHIBITORS OF PORCINE PANCREATIC ALPHA-AMYLASE - STRUCTURE ANALYSIS AND COMPARISON OF THEIR BINDING CHARACTERISTICS
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CARBOHYDRATE AND PROTEIN-BASED INHIBITORS OF PORCINE PANCREATIC ALPHA-AMYLASE - STRUCTURE ANALYSIS AND COMPARISON OF THEIR BINDING CHARACTERISTICS

机译：猪胰腺α-淀粉酶的碳水化合物和基于蛋白质的抑制剂-结构分析和结合特性的比较

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The crystal structures of porcine pancreatic alpha-amylase isozyme II (PPA II) in its free form and complexed with the trestatin A derived pseudo-octasaccharide V-1532 have been determined using Patterson search techniques at resolutions of 2.3 and 2.2 Angstrom, respectively. Seven rings of the competitive inhibitor V-1532 could be detected in the active site region as well as two maltose units in secondary binding sites on the surface. V-1532 occupies the five central sugar binding subsites similar to the PPA/acarbose structure. A sixth ring exists at the reducing end, connecting two symmetry related PPA molecules. The seventh moiety, a 6-hydroxymethylconduritol ring, is located at the non-reducing end. The electron density for this ring is relatively weak, indicating considerable disorder. This study shows that PPA is able to accommodate more than five rings in the active site region, but that additional rings would increase the binding affinity only slightly, which is in accordance with kinetic experiments. A comparison of the structures of free PPA, PPA/V-1532 and PPA/Tendamistat shows the characteristic conformational changes that accompany inhibitor binding and distinguish pseudo-oligosaccharide inhibitors from proteinaceous inhibitors. Although both classes of inhibitors block the sugar binding subsites in the active site region, the extreme specificity and binding affinity of the proteinaceous inhibitors is probably due to an intricate interaction pattern involving areas further away from the catalytic center. (C) 1996 Academic Press Limited [References: 50]
机译：游离胰腺猪胰α-淀粉酶同工酶II（PPA II）的晶体结构，并与视黄素A衍生的伪八糖V-1532复合，已使用Patterson搜索技术确定了分辨率，分别为2.3和2.2埃。可以在活性位点区域检测到七个竞争抑制剂V-1532的环，并在表面的次级结合位点检测到两个麦芽糖单元。 V-1532占据了五个中心糖结合亚位点，类似于PPA /阿卡波糖的结构。第六环存在于还原端，连接两个对称相关的PPA分子。第七部分是6-羟甲基conduritol环，位于非还原端。该环的电子密度相对较弱，表明存在相当大的混乱。这项研究表明，PPA能够在活性位点区域容纳5个以上的环，但是额外的环只会稍微增加结合亲和力，这与动力学实验一致。游离PPA，PPA / V-1532和PPA / Tendamistat的结构比较表明，伴随抑制剂结合而发生的特征性构象变化，使伪寡糖抑制剂与蛋白质抑制剂区别开来。尽管这两类抑制剂都阻断了活性位点区域中的糖结合亚位点，但蛋白质抑制剂的极高特异性和结合亲和力可能是由于复杂的相互作用模式所致，该相互作用模式涉及了远离催化中心的区域。 （C）1996 Academic Press Limited [参考：50]

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