EN
A new crystal form of papain from the latex of Carica papaya, complexed with an inhibitor (Z-Arg-Leu-Val-Gly-CHN2) was obtained by the vapor-diffusion method using a methanol/ethanol mixture as a precipitant. The slat-like crystals are monoclinic, space group P2 1, with unit cell parameters a = 42.6 A, b = 49.8 A, c = 50.5 A, β= 111.9°, and contain one molecule in the asymmetric unit. The crystals are stable in the X-ray beam and diffract beyond 1.8 A. A molecular model has been placed in the unit cell by molecular replacement.