The Complete Primary Structure Elucidation of Aspergillus ficuum (Niger), pH-6.0, Optimum Acid-Phosphatase by Edman Degradation

Abstract

The primary structure of the Aspergillus ficuum (niger) NRRL 3135 extracellular, pH 6.0, optimum acid phosphatase (E.C.3.1.3.2) was elucidated by gas phase sequencing. It was deduced by sequence overlap of peptides obtained from trypsin, chymotrypsin, clostripain, and cyanogen bromide digests of the pyridylethylated protein. The mature, active protein is composed of 583 amino acids, including 13 glycosylated Asn residues. The unglycosylated protein has a MW of 64,245-KDa and a pl of 4.97. Two putative metal binding sites were identified in the molecule. This enzyme may represent a special class of high molecular weight acid phosphatase, since it lacks the active site sequence RHGXRXP and shows no significant homology with known acid phosphatases containing this active site. Homology to human type 5 and A.niger APases was detected, however.