1rmh
From Proteopedia
RECOMBINANT CYCLOPHILIN A FROM HUMAN T CELL
Overview
The crystal structure of human recombinant cyclophilin A complexed with a substrate of succinyl-Ala-Ala-Pro-Phe-p-nitroanilide (AAPF) has been determined and refined to an R-factor of 0.189 at 2.4 A resolution. The structure revealed only the cis form of the substrate bound to cyclophilin A in a stoichiometry of 1:1. This binding ratio is different from the structure of cyclophilin A complexed with the tetrapeptide N-acetyl-Ala-Ala-Pro-Ala-amidomethylcourmarin. Model docking revealed that the trans form of AAPF does not fit into the active site. The observation that only the trans cis form of AAPF binds to cyclophilin A implies that cyclophilin A predominantly catalyzes the trans to cis isomerization of a peptidylprolyl amide bond. On the basis of the structure, it is proposed that Arg55 hydrogen-bonds to the nitrogen to deconjugate the resonance of the prolyl amide bond and thus facilitates the cis-trans rotation.
About this Structure
1RMH is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Crystal structure implies that cyclophilin predominantly catalyzes the trans to cis isomerization., Zhao Y, Ke H, Biochemistry. 1996 Jun 11;35(23):7356-61. PMID:8652511 Page seeded by OCA on Sat May 3 07:40:20 2008
