Purification of Alkaline Proteinase from Aspergillus candidus

Abstract

An alkaline proteinase of Aspergillus candidus was purified from wheat bran solid culture by batchwise treatment with Amberlite IRC-50 and sequential chromatography on DEAE-cellulose, hydroxylapatite and Sephadex G-100 gel. This purification results in a 18-fold increase of proteolytic activity and the enzyme preparation was homogeneous in sedimentation analysis of the ultracentrifuge and polyacrylamide gel disc electrophoresis. The molecular weight was estimated to be about 23, 000 by gel glltration and 22, 000 by calculation from the amino acid composition. The enzyme consisted of Lys₁₄, His₄, Arg₃, Asp₂₅, Thr₁₅, Ser₂₃, Glu₁₅, Pro₇, Gly₂₂, Ala₂₄, Met₂, Val₁₆, Ile₁₁, Leu₁₀, Tyr₆, Phe₇, Trp₂ and amide ammonia₁₄ and did not contain cysteine or cystine.