Reinvestigation of Molecular Weight and Terminal Amino Acid Residues of Alkaline Proteinase from Aspergillus sojae^†

Abstract

The partial specific volume of the alkaline proteinase from Aspergillus sojae, determined from density measurement, was 0.696 ml/g. This value is 4.1% lower than the value calculated from the known specific volumes of constituent amino acid residues. The difference between the two values of partial specific volume has a considerable influence on the calculation of molecular weight. The molecular weight, determined by the Yphantis’ procedure and based on the experimentally determined partial specific volume, gave a value of 22,600. The gel filtration behavior of the enzyme showed that the value of molecular weight appeared to be reasonable. The amino- and carboxyl-terminal amino acids of the enzyme were shown to be glycine and alanine, respectively, and leucine was the penultimate amino acid on the carboxyl-terminal of the enzyme.