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Protein purification and nucleotide sequence of a lysozyme from the bacteria-induced larvae of the fall webworm, Hyphantria cunea

Park, H.Y., Park, S.S., Shin, S.W., Park, D.S., Kim, M.G., Oh, H.W., Joo, C.K.
Archives of insect biochemistry and physiology 1997 v.35 no.3 pp. 335-345
lysozyme, messenger RNA, Hyphantria cunea, complementary DNA, structural genes, phylogeny, amino acid sequences, gene expression, nucleotide sequences, immune response, enzyme activity, Escherichia coli
A protein with lytic activity against Micrococcus luteus was purified from the hemolymph of the fall webworm, Hyphantria cunea, larvae challenged with live E. coli. A bacteriolytic protein of about 14,000 daltons in mass was purified by cation exchange chromatography and reverse-phased HPLC. The optimum pH and optimum temperature range for activity were around pH 6.2 and 50 degrees C, respectively, in a 100 mM phosphate buffer. The amino-terminal amino acid sequence of this protein was determined and the corresponding cDNA was isolated and analyzed. The deduced protein of 142 amino acid residues was composed of a putative leader sequence of 20 residues and the mature enzyme of 122 residues. The cloned lysozyme gene was strongly induced in response to bacterial injection, implying that the enzyme is a part of the immune response of H. cunea. Comparison with other known lysozyme sequences shows that our lysozyme belongs to the chicken lysozyme.