Delbaere L T, Brayer G D, James M N
Can J Biochem. 1979 Feb;57(2):135-44. doi: 10.1139/o79-017.
The 2.8 A (1 A = 0.1 nm) resolution structure of the crystalline orthorhombic form of the microbial serine protease Streptomyces griseus protease B (SGPB) has been solved by the method of multiple isomorphous replacement using five heavy-atom derivatives. The geometrical arrangement of the active site quartet, Ser-214, Asp-102, His-57, and Ser-195, is similar to that found for pancreatic alpha-chymotrypsin. SGPB and alpha-chymotrypsin have only 18% identity of primary structure but their tertiary structures are 63% topologically equivalent within a root mean square deviation of 2.07 A. The major tertiary structural differences between the bacterial enzyme SGPB and the pancreatic enzymes is due to the zymogen requirement of the multicellular organisms in order to protect themselves against autolytic degradation. The two pronase enzymes, SGPB and Streptomyces griseus protease A (SGPA), have 61% identity of sequence and their tertiary structures are 85% topologically equivalent within a root mean square deviation of 1.46 A. The active site regions of SGPA and SGPB are similar and their tertiary structures differ only in three minor regions of surface loops.
利用五个重原子衍生物,通过多同晶置换法解析了微生物丝氨酸蛋白酶灰色链霉菌蛋白酶B(SGPB)晶体正交晶型的2.8埃(1埃 = 0.1纳米)分辨率结构。活性位点四重奏Ser-214、Asp-102、His-57和Ser-195的几何排列与胰凝乳蛋白酶α的相似。SGPB与胰凝乳蛋白酶α的一级结构仅有18%的一致性,但它们的三级结构在均方根偏差为2.07埃的范围内拓扑等效性为63%。细菌酶SGPB与胰酶之间主要的三级结构差异是由于多细胞生物的酶原需求,以便保护自身免受自溶降解。两种链霉蛋白酶,SGPB和灰色链霉菌蛋白酶A(SGPA),序列一致性为61%,它们的三级结构在均方根偏差为1.46埃的范围内拓扑等效性为85%。SGPA和SGPB的活性位点区域相似,它们的三级结构仅在表面环的三个小区域有所不同。