STRUCTURE OF HUMAN ALPHA-THROMBIN Y225F MUTANT BOUND TO D-PHE-PRO-ARG-CHLOROMETHYLKETONE

Unexpected crucial role of residue 225 in serine proteases.

IVEGSDAEIGMSPWQVMLFRKSPQELLCGASLISDRWVLTAAHCLLYPPWDKNFTENDLLVRIGKHSRTRYERNIEKISM
LEKIYIHPRYNWRENLDRDIALMKLKKPVAFSDYIHPVCLPDRETAASLLQAGYKGRVTGWGNLKETWTANVGKGQPSVL
QVVNLPIVERPVCKDSTRIRITDNMFCAGYKPDEGKRGDACEGDSGGPFVMKSPFNNRWYQMGIVSWGEGCDRDGKFGFY
THVFRLKKWIQKVIDQFGE

D-PHE-PRO-ARG-CHLOROMETHYLKETONE HAS FORMED TWO COVALENT
CONNECTIONS TO THROMBIN:
1) VIA A HEMIKETAL GROUP TO OG SER B 195.
2) VIA A METHYLENE GROUP TO NE2 HIS B 57.

THE PROTEIN USED IN THE PRESENT STRUCTURE DETERMINATION COMPRISED AMINO ACIDS 1H TO 247 (CHYMOTRYPSIN NUMBERING) OF HUMAN ALPHA THROMBIN. RESIDUE TYR B 225 WAS MUTATED TO PHE. DUE TO LACK OF ELECTRON DENSITY RESIDUES 1H THROUGH 1B (7 TOTAL) COULD NOT BE BUILT, AS WELL AS RESIDUES 147 THROUGH 149E (8 TOTAL), AND RESIDUES 246 AND 247.

SERINE PROTEASE, HYDROLASE-HYDROLASE INHIBITOR complex

IVEGSDAEIGMSPWQVMLFRKSPQELLCGASLISDRWVLTAAHCLLYPPWDKNFTENDLLVRIGKHSRTRYERNIEKISM
LEKIYIHPRYNWRENLDRDIALMKLKKPVAFSDYIHPVCLPDRETAASLLQAGYKGRVTGWGNLKETWTANVGKGQPSVL
QVVNLPIVERPVCKDSTRIRITDNMFCAGYKPDEGKRGDACEGDSGGPFVMKSPFNNRWYQMGIVSWGEGCDRDGKYGFY
THVFRLKKWIQKVIDQFGE