title: Isolation, characterization, kinetics, and enzymatic and nonenzymatic microbicidal activities of a novel c-type lysozyme from plasma of Schistocerca gregaria (Orthoptera: Acrididae).
abstract: A protein, designated as Sgl, showing a muramidase lytic activity to the cell wall of the Gram-positive bacterium Micrococcus lysodeikticus was isolated for the first time from plasma of Escherichia coli-immunized fifth instar Schistocerca gregaria. The isolated Sgl was detected as a single protein band, on both native- and SDS-PAGE, has a molecular weight of ∼15.7 kDa and an isoelectric point (pI) of ca 9.3 and its antiserum has specifically recognized its isolated form. Fifty-nine percentage of Sgl lytic activity was recovered in the isolated fractions and yielded ca 126-fold increase in specific activity than that of the crude. The partial N-terminal amino acid sequence of the Sgl has 55 and 40% maximum identity with Bombyx mori and Gallus gallus c-type lysozymes, respectively. The antibacterial activity against the Gram-positive and the Gram-negative bacteria were comparatively stronger than that of the hen egg white lysozyme (HEWL). The detected Sgl poration to the inner membrane that reach a maximum ability after 3 h was suggested to operate as a nonenzymatic mechanism for Gram-negative bacterial cell lysis, as tested in a permease-deficient E. coli, ML-35 strain. Sgl showed a maximal muramidase activity at pH 6.2, 30-50°C, and 0.05 M Ca(2+) or Mg(2+); and has a Km of 0.5 μg/ml and a Vmax of 0.518 with M. lysodeikticus as a substrate. The Sgl displayed a chitinase activity against chitin with a Km of 0.93 mg/ml and a Vmax of 1.63.
authors.affiliation: Department of Entomology, Faculty of Science, Cairo University, P. O. Box 12613, Giza, Egypt Department of Biology, Faculty of Applied Science, Umm AlQura University, P.O. Box 673, Makkah, KSA.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Elmogy
authors.affiliation: Department of Entomology, Faculty of Science, Cairo University, P. O. Box 12613, Giza, Egypt taha@sci.cu.edu.eg.
authors.forename: Taha T M
authors.initials: TT
authors.lastname: Bassal
authors.affiliation: Department of Entomology, Faculty of Science, Cairo University, P. O. Box 12613, Giza, Egypt.
authors.forename: Hesham A
authors.initials: HA
authors.lastname: Yousef
authors.affiliation: Department of Entomology, Faculty of Science, Cairo University, P. O. Box 12613, Giza, Egypt.
authors.forename: Moataza A
authors.initials: MA
authors.lastname: Dorrah
authors.affiliation: Department of Entomology, Faculty of Science, Cairo University, P. O. Box 12613, Giza, Egypt.
authors.forename: Amr A
authors.initials: AA
authors.lastname: Mohamed
authors.affiliation: Institut National de la Recherche Agronomique (INRA), UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), 34095 Montpellier Cedex 05, France Université Montpellier 2, UMR Diversité, Génomes et Interactions Microorganismes-Insectes (DGIMI), 34095 Montpellier Cedex 05, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Duvic
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification*; D002688:Chitinases / Q000032:analysis; D006110:Grasshoppers / Q000201:enzymology*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000378:metabolism; D009113:Muramidase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000890:Anti-Infective Agents; D014442:Monophenol Monooxygenase; D002688:Chitinases; D009113:Muramidase
keywords: Schistocerca gregaria; antibacterial activity; kinetics; lysozyme c; muramidase