THE 2.5 A X-RAY CRYSTAL-STRUCTURE OF THE ACID-STABLE PROTEINASE-INHIBITOR FROM HUMAN MUCOUS SECRETIONS ANALYZED IN ITS COMPLEX WITH BOVINE ALPHA-CHYMOTRYPSIN
THE 2.5 A X-RAY CRYSTAL-STRUCTURE OF THE ACID-STABLE PROTEINASE-INHIBITOR FROM HUMAN MUCOUS SECRETIONS ANALYZED IN ITS COMPLEX WITH BOVINE ALPHA-CHYMOTRYPSIN
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DOI：
10.1002/j.1460-2075.1988.tb02819.x
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发表时间：
1988-02-01
期刊：
影响因子：
11.4
通讯作者：
BODE, W
中科院分区：
文献类型：
--
作者：
GRUTTER, MG;FENDRICH, G;BODE, W
牛α-之间形成的复合物的正交晶体胰凝乳蛋白酶和重组人粘液蛋白酶抑制剂（SLPI）生长。数据至2.3. ANG。在面积检测器衍射仪FAST上收集分辨率。以胰凝乳蛋白酶为搜索模型，用Patterson搜索技术求解了配合物的晶体结构。一个循环程序的建模和晶体学的完善，使SLPI结构的测定。目前的晶体学R值为0.19。SLPI具有回飞棒样形状，其两翼包含两个结构相似的良好分离的结构域。在每个结构域中，多肽链像伸展的螺旋一样排列。两条内部链形成规则的β-发夹环，其伴随有由蛋白酶结合片段连接的两条外部链。每个结构域的多肽片段通过四个二硫桥相互连接，具有迄今未观察到的连接模式。第二结构域的反应位点环具有弹性蛋白酶和胰凝乳蛋白酶结合特性。它含有Leu 72 I和Met 73 I之间的易断裂的肽键，并且具有与在其他丝氨酸蛋白酶蛋白抑制剂中观察到的构象相似的构象。该环的8个残基、相邻发夹环的2个残基、C-末端片段和Trp-30 I与同源酶直接接触。第一个结构域（可能具有抗胰蛋白酶活性）的结合环由于结晶过程中发生的蛋白水解裂解而无序。
Orthorhombic crystals of the complex formed between bovine .alpha.-chymotrypsin and a recombinant human mucous proteinase inhibitor (SLPI) were grown. Data to 2.3 .ANG. resolution were collected on the area-detector diffractometer FAST. The crystal structure of the complex was solved by Patterson search techniques using chymotrypsin as a search model. A cyclic procedure of modeling and crystallographic refinement enabled the determination of the SLPI structure. The current crystallographic R-value is 0.19. SLPI has a boomerang-like shape with both wings comprising two well separated domains of similar architecture. In each domain the polypeptide chain is arranged like a stretched spiral. Two internal strands form a regular .beta.-hairpin loop which is accompanied by two external strands linked by the proteinase binding segment. The polypeptide segment of each domain is interconnected by four disulfide bridges with a connectivity pattern hitherto unobserved. The reactive site loop of the second domain has elastase and cymotrypsin binding properties. It contains the scissile peptide bond between Leu72I and Met73I and has a similar conformation to that observed in other serine proteinase protein inhibitors. Eight residues of this loop, two of the adjacent hairpin loop, the C-terminal segment and Trp-30I are in direct contact with the cognate enzyme. The binding loop of the first domain (probably with antitrypsin activity) is disordered due to proteolytic cleavage occurring in the course of crystallization.