Purification and Properties of a Proteinase from a Marine Luminous Bacterium, Vibrio harveyi Strain FLA-11

Abstract

A proteolytic, marine luminous bacterium was isolated from seawater and identified as Vibrio harveyi strain FLA-11. A proteinase from this strain, with a specific activity 61-fold higher than that of the culture supernatant, was purified to homogeneity. The purified enzyme had a molecular weight of 84,000, comprising a tetramer of 21,000 molecular weight subunits. The enzyme was most active at pH 8.0 and 55°C, and stable below 40°C. The enzyme activity was completely inhibited by EDTA, orthophenanthrolin and phosphoramidon. Metal ions such as Cu²⁺, Hg^{2 +}, Ni^{2 +}, Cd^{2 +} and Co²⁺ also inhibited the activity. These results indicate that this enzyme is a metal-chelater- sensitive, alkaline proteinase.