Purification and partial characterization of a calcium‐stimulated protease from the cyanobacterium, Anabaena variabilis

Publisher Website
Google Scholar
Abstract
A calcium-stimulated protease was purified to apparent homogeneity from the heterocyst-forming cyanobacterium Anabaena variabilis ATCC 29413. As judged from experiments with inhibitors and chromogenic peptide substrates, the enzyme is a serine protease with a substrate specificity like trypsin. Its apparent relative molecular mass is 52000. Calcium depletion inhibits the enzymic activity by 92%. Half-maximal activity requires about 0.5 .mu.M free Ca2+. The enzyme binds to a hydrophobic column in a calcium-dependent manner, indicating calcium-induced exposure of a hydrophobic domain. The possible role of the protease in heterocyst differentiation is discussed.