Crystal and molecular structure of the inhibitor eglin from leeches in complex with subtilisin Carlsberg

Abstract

The crystal structure of the molecular complex of eglin, a serine proteinase inhibitor from leeches, with subtilisin Carlsberg has been determined at 2.0 A resolution by the molecular replacement method. The complex has been relined by restrained-parameter least-squares. The present crystallographic R factor (=CI ]13,\-]1;1 I/ClF,I) is 0.183. Eglin is a member of the potato inhibitor 1 family, a group of serine proteinase inhibitors lacking disultide bonds. Eglin shows strong structural homology to CL2, a related inhibitor from barley seeds. The structure of subtilisin Carlsberg in this complex is very similar to the known structure of subtilisin novo, despite changes of 84 out of 274 amino acids. Potato inhibitor 1 Serine proteinase Molecular replacement method Hirudo medicinalisCrystallography

Complex between the subtilisin from a mesophilic bacterium and the Leech inhibitor eglin-C

“…In contrast, the Ca2 site reported for SBPN is different in character, and may not be occupied by calcium. The crystallization conditions reported for SBCARL-eglin-C did not include calcium (McPhalen, Schnebli et al, 1985;Bode et al, 1986). In the present study 5 mM CaCI2 was present in the crystallization solution.…”

Subtilisin enzymes: A note on time‐resolved fluorescence and circular dichroism properties

“…These two proteins have about 70% sequence identity [1]. X-ray crystal structures [2][3][4][5] show that the two proteins have very similar structure: the a-carbon backbone conformations differ only to an r.m.s, deviation of 0.53 A for 274 residues, [4]. Most of the 84 sequence substitutions involve surface residues.…”

Amino‐acid‐sequence Determination and Biological Activity of Cytin, a Naturally Occurring Specific Chymotrypsin Inhibitor from the Leech Theromyzon tessulatum

“…bdellins [9]). Cytin, similarly to eglin, possesses sequence identity with the substilisin/ chymotrypsin-inhibitor (I) family isolated from barley seeds [23]. Alignment of N-terminal sequences (first 22 residues) of the B chain of cytin with CI-2a revealed 73% residue identity (Table 2) and 52-67% residue identities with CI-1 (a, b and c) and CI-2b, respectively.…”