1ANE

ANIONIC TRYPSIN WILD TYPE

Summary for 1ANE

• Entry DOI: 10.2210/pdb1ane/pdb
• Descriptor: ANIONIC TRYPSIN, BENZAMIDINE (3 entities in total)
• Functional Keywords: trypsin, anionic, serine protease, hydrolase
• Biological source: Rattus rattus (black rat)
• Cellular location: Secreted, extracellular space: P00763
• Total number of polymer chains: 1
• Total formula weight: 23934.99

Authors

Fletterick, R.J.,Mcgrath, M.E. (deposition date: 1994-12-21, release date: 1997-04-01, Last modification date: 2024-06-05)

Primary citation

McGrath, M.E.,Haymore, B.L.,Summers, N.L.,Craik, C.S.,Fletterick, R.J.
Structure of an engineered, metal-actuated switch in trypsin.
Biochemistry, 32:1914-1919, 1993

PubMed Abstract: The X-ray crystal structure of the copper complex of the rat trypsin mutant Arg96 to His96 (trypsin R96H) has been determined in order to ascertain the nature of the engineered metal-binding site and to understand the structural basis for the metal-induced enzymatic inhibition. In the structure, the catalytically essential His57 residue is reoriented out of the active-site pocket and forms a chelating, metal-binding site with residue His96. The copper is bound to the N epsilon 2 atoms of both histidine residues with Cu-N epsilon 2 = 2.2 A and N epsilon 2-Cu-N epsilon 2 = 89 degrees. The metal is clearly bound to a third ligand leading to a distorted square planar geometry at Cu. The X-ray results do not unambiguously yield the identity of this third ligand, but chemical data suggest that it is a deprotonated, chelating Tris molecule which was used as a carrier to solubilize the copper in alkaline solution (pH 8.0). Upon reorientation of His57, a unique water molecule moves into the active site and engages in hydrogen-bonding with Asp102-O delta 2 and His57-N delta 1. Except for small movements of the peptide backbone near His96, the remainder of the trypsin molecule is isostructural with the native enzyme. These data support the notion that the effective inhibition of catalytic activity by metal ions observed in trypsin R96H is indeed caused by a specific and reversible reorganization of the active site in the enzyme.

PubMed: 8448149
DOI: 10.1021/bi00059a005

Experimental method

X-RAY DIFFRACTION (2.2 Å)