Thrombin derivatives and medicinal composition containing the same

It is intended to provide a thrombin derivative comprising A and B chains wherein the B chain has an amino acid sequence derived from the amino acid sequence of thrombin B chain by the substitution at one or more active center amino acids selected from among serine at the 205-position, glycine at the 203-position, aspartic acid at the 99-position and histidine at the 43-position, and (1) in the case of reacting with a thrombin substrate at 37C for 3 hours in a 50 mM tris hydrochloride buffer (pH 7.4) containing 0.1 M of NaCl, the ratio of the thrombin substrate decomposed by the thrombin derivative being 10% or lower; and (2) sustaining the structure of exocite I.