Isolation and biochemical characterization of a gamma-type phospholipase A2 inhibitor from Macropisthodon rudis snake serum

•Isolation of a novel gamma-type PLA2 inhibitory protein from Macropisthodon rudis snake serum.•The amino acid sequences of the cDNAs were analyzed with other related inhibitors by multiple sequence alignment.•Phylogenetic trees were constructed to study their evolutionary relationship.•PLIγ neutralizes the enzymatic, inflammatory, and antibacterial activities of a PLA2 isolated from Agkistrodon acutus.

A novel phospholipaseA2 (PLA2) inhibitory protein (PLI) was purified from the serum of Macropisthodon rudis, a non-venomous snake mainly found in southern China. The molecular mass of the purified PLI was 160 kDa as determined by Superdex 200HR; however, the PLI protein had only one subunit of 25.4 kDa as determined by 12% SDS-PAGE, indicating an oligomeric protein. PLI cDNA obtained by PCR from the liver of Macropisthodon rudis, revealed 549 bps coding for a mature protein of 183 amino acid residues. Based on an amino acid sequence alignment with venomous and non-venomous snakes, this inhibitor was determined to be in the γ type family of PLI. In vitro experiments showed that PLIγ inhibited enzymatic, inflammatory, and antibacterial activities of snake venom PLA2 isolated from Agkistrodon acutus.