Primary structure of a nuclease (nuclease PA3) from a Penicillium sp

The complete primary structure of a nuclease from a Penicillium sp. [nuclease PA3 (Kazama et al., Chem. Pharm. Bull., 38, 3081 (1990)] was determined. The sequencing was done by analysis of the peptides generated by digestion of reduced and carboxymethylated nuclease PA3 (RCM nuclease PA3) with lysylendopeptidase, and by digestion with staphylococcal V8 protease or chemical cleavage with BrCN. It consisted of 270 amino acid residues and carbohydrate moieties attached to the 92nd, 138th, 184th, and 197th asparagine residues. The molecular weight of the protein moiety deduced from the sequence was 29,211. It contains four half cystine residues. The amino acid sequence was identical with that of P1 nuclease from Penicillium citrinum [K. Maekawa, S. Tsunasawa, G. Dibo, and F. Sakiyama, Abstracts of Papers, the 62nd Meeting of the Biochemical Society of Japan, Seikagaku, 61, 1013 (1989)] except that the 190th Thr residue was Ile in P1 nuclease.