Amino acid sequence of alkaliphilic serine protease from silkworm, <i>Bombyx mori</i>, larval digestive juice

Abstract

Alkaliphilic protease, P-IIc, from silkworm, Bombyx mori, larval midgut digestive juice consists of 232 amino acids. It has a catalytic triad, Asp-His-Ser, invariably found in a serine protease. A shift of optimal pH value towards the alkaline side diminished at mu = 1.0. This suggests the existence of an electrostatic interaction that affects the proteolytic activity. The higher Arg content may be responsible for this phenomenon. Two cysteine residues probably exist unpaired in a novel position among serine proteases.