title: Purification and characterization of lysozyme from plasma of the eastern oyster (Crassostrea virginica).
abstract: Lysozyme was purified from the plasma of eastern oysters (Crassostrea virginica) using a combination of ion exchange and gel filtration chromatographies. The molecular mass of purified lysozyme was estimated at 18.4 kDa by SDS-PAGE, and its isoelectric point was greater than 10. Mass spectrometric analysis of the purified enzyme revealed a high-sequence homology with i-type lysozymes. No similarity was found however between the N-terminal sequence of oyster plasma lysozyme and N-terminal sequences of other i-type lysozymes, suggesting that the N-terminal sequences of the i-type lysozymes may vary to a greater extent between species than reported in earlier studies. The optimal ionic strength, pH, cation concentrations, sea salt concentrations, and temperature for activity of the purified lysozyme were determined, as well as its temperature and pH stability. Purified oyster plasma lysozyme inhibited the growth of Gram-positive bacteria (e.g., Lactococcus garvieae, Enterococcus sp.) and Gram-negative bacteria (e.g., Escherichia coli, Vibrio vulnificus). This is a first report of a lysozyme purified from an oyster species and from the plasma of a bivalve mollusc.
authors.affiliation: Cooperative Aquatic Animal Health Research Program, Department of Veterinary Science, Louisiana State University Agricultural Center, 111 Dalrymple Building, Baton Rouge, LA 70803, USA.
authors.forename: Qing-Gang
authors.initials: QG
authors.lastname: Xue
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Schey
authors.forename: Aswani K
authors.initials: AK
authors.lastname: Volety
authors.forename: Fu-Lin E
authors.initials: FL
authors.lastname: Chu
authors.forename: Jerome F
authors.initials: JF
authors.lastname: La Peyre
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification; D002412:Cations / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006458:Hemolymph / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D008145:Louisiana; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009113:Muramidase / Q000097:blood* / Q000737:chemistry / Q000302:isolation & purification*; D009994:Osmolar Concentration; D010125:Ostreidae / Q000201:enzymology*; D012623:Seawater; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013696:Temperature
chemical_list: D000900:Anti-Bacterial Agents; D002412:Cations; D009113:Muramidase