From: H.KE,L.D.ZYDOWSKY,J.LIU,C.T.WALSH (1991) CRYSTAL STRUCTURE OF RECOMBINANT HUMAN T CELL CYCLOPHILIN A AT 2.5 ANGSTROMS RESOLUTION. PROC.NAT.ACAD.SCI.USA 88 9483.

Courtesy of Molecules R Us, a wonderful web site set up by the National Institutes of Health.