Protein purification and gene isolation of chlamysin, a cold-active lysozyme-like enzyme with antibacterial activity

An antibacterial similar to 11 kDa protein designated chlamysin was isolate d from viscera of the marine bivalve Chlamys islandica. Chlamysin inhibited the growth of ail Grampositive and Gram-negative bacteria tested. The isol ated protein was highly efficient in hydrolyzing Micrococcus luteus cells o nly at low pH (4.5-6.2) and at low temperature (4-35 degrees C), No signifi cant loss of enzyme activity was observed after 30 days storage at room tem perature or after heating to 70 degrees C for 15 min, suggesting relatively high protein structure stability. Sequence-analyzed fragments of the prote in revealed data which guided the isolation of the cDNA gene, encoding a 13 7 amino acid chlamysin precursor in scallops. The deduced protein contains a high portion of cysteine, serine and histidine residues and has a predict ed isoelectric point below 7, The chlamysin protein was found to have seque nce homology to an isopeptidase and to a recently published bivalve lysozym e, (C) 1999 Federation of European Biochemical Societies.