Loop closure and intersubunit communication in tryptophan synthase.

摘要: Crystal structures of wild-type tryptophan synthase α2β2 complexes from Salmonella typhimurium were determined to investigate the mechanism allosteric activation α-reaction by aminoacrylate intermediate formed at β-active site. Using a flow cell, (A-A) β-reaction ( ) was generated in crystal under steady state conditions presence serine and α-site inhibitor 5-fluoroindole propanol phosphate (F-IPP). A model for conformation Schiff base between β-subunit cofactor pyridoxal (PLP) is presented. The structure compared with enzyme absence (TRPS) (TRPSF-IPP) F-IPP. detailed binding F-IPP α-subunit In contrast findings Hyde et al. [(1988) J. Biol. Chem. 263,17857−17871] Rhee [(1997) Biochemistry 36, 7664−7680], we find that an alone ligand sufficient loop αL...