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Research has been conducted on human group IIA secreted phospholipase A (sub)2. The preparation of phospholipase's H48Q and H48N mutants and the analysis of H48N and H48Q enzymes' activity are discussed.

The ability of fatty acid-binding proteins to interact with phospholipid interfaces that contain anionic phospholipids has been investigated. Results indicate that a complete loss of legand can be caused by the interaction with small phospholipid vesicles.

The mutation of the interfacial valine of human secreted phospholipase A2 (sPLA2) to a tryptophan was found to demonstrate the ability of this amphiphilic indole residue. The residue substantially improves the hydrolysis of zwitterionic interfaces found in the form of small unilamellar vesicles of phosphatidylcholine or cell membranes. Findings are in good agreement with the function of interfacial tryptophans of venom enzymes in permitting the penetration and hydrolysis of such condensed bilayers.

Human secretory group IIa phospholipase Asub2 (hIIa-PLAsub2) has high affinity for anionic surfaces such as anionic membranes. Site-directed mutagenesis of the protein was carried out to identify the cationic amino acid residues supporting binding to anionic membranes. Results suggest that electrostatic interactions between surface lysine and arginine residues and the interface contribute to interfacial hIIa-PLAsub2 binding to anionic vesicles.

The complex kinetic effects of gossypol and sulfated conjugates on phospholipid A2 activity were analyzed through quantitative determination of the primary rate and equilibrium constants for the catalytic turnover. Gossypol inactivated PLA2 through covalent modification of the alpha amino group at the amino terminal. Sulfated conjugates sequester the circulating PLA2 thereby altering the proteoglycan matrix which resulted in the loss of the regulatory role.

Research has been conducted on human group IIA phospholipase A (sub)2. Results demonstrate that the insertion of tryptophan produces mutants which can enhance human IIA enzyme activity against intact cell membranes and zwitterionic interfaces.