Abstract
RC-RNases are ribonucleases from Rana catesbeiana oocytes with pyrimidine-guanine sequence specificity. They also possess cell cytotoxicity and lectin activity. Protein crystals of three RC-RNase isozymes, RC-RNase 3, RC-RNase 4 and RC-RNase 6, were grown in various crystal systems under different conditions. Crystals of RC-RNase3 belong to the orthorhombic C222 1 space group, with unit-cell parameters a = 66.66, b = 97.38, c = 85.74 Å. Crystals of RC-RNase 4 belong to the trigonal space group P3 1 or P3 2 , with unit-cell parameters a = b = 32.22, c = 92.12 Å. Crystals of RC-RNase 6 complexed with cytidylyl 2′-5′ guanosine belong to the tetragonal space group P4 1 2 1 2 or P4 3 2 1 2, with unit-cell parameters a = b = 61.80, c = 65.96 Å.