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Biochemistry Research International
Volume 2011, Article ID 925012, 7 pages
http://dx.doi.org/10.1155/2011/925012
Research Article

Characterization of Serum Phospholipase A2 Activity in Three Diverse Species of West African Crocodiles

1Department of Chemistry, McNeese State University, 450 Beauregard, Kirkman Hall 221A, Lake Charles, LA 70609, USA
2Department of Wildlife Ecology & Conservation, University of Florida, Gainesville, FL, USA

Received 27 March 2011; Revised 21 July 2011; Accepted 25 July 2011

Academic Editor: Sanford I. Bernstein

Copyright © 2011 Mark Merchant et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Secretory phospholipase A2, an enzyme that exhibits substantial immunological activity, was measured in the serum of three species of diverse West African crocodiles. Incubation of different volumes of crocodile serum with bacteria labeled with a fluorescent fatty acid in the sn-2 position of membrane lipids resulted in a volume-dependent liberation of fluorescent probe. Serum from the Nile crocodile (Crocodylus niloticus) exhibited slightly higher activity than that of the slender-snouted crocodile (Mecistops cataphractus) and the African dwarf crocodile (Osteolaemus tetraspis). Product formation was inhibited by BPB, a specific PLA2 inhibitor, confirming that the activity was a direct result of the presence of serum PLA2. Kinetic analysis showed that C. niloticus serum produced product more rapidly than M. cataphractus or O. tetraspis. Serum from all three species exhibited temperature-dependent PLA2 activities but with slightly different thermal profiles. All three crocodilian species showed high levels of activity against eight different species of bacteria.