Heparin reduces the α-helical content of cobra basic phospholipase A2 and promotes its complex formation

The interaction of phospholipase A2 (PLA2) with glycosaminoglycans (GAGs) has recently attracted attention in view of its implication on inflammation and cell proliferation. By using Fourier Transformed Infrared (FTIR) spectroscopic measurements, we demonstrate here that binding of cobra basic phospholipase A2 from Naja nigricollis (N-PLA2) to heparin may induce a significant conformational change observed in the amide I region of the enzyme’s α-helical and β-sheet structure. It is observed that notable conformational change of N-PLA2 due to heparin binding occurs only when heparin’s chain length is at least an octasaccharide as evidenced by circular dichroism and optical density measurements. This correlation may be an important factor in the aggregation of N-PLA2 and N-PLA2–heparin complexes. Heparin induced change in conformation of PLA2 is suggested to be a notable link in understanding the diversity in PLA2 activity when rendered to the extracellular matrix of cell membranes that is full of GAG molecules.