Tryptophan residues of phospholipase A2 from the venom of an Australian elapid snake (Pseudechis australis)

摘要: Abstract S. Nishida and N. Tamiya . Tryptophan residues of phospholipase A2 from the venom an Australian elapid snake (Pseudechis australis). Toxicon29, 429–439, 1991.—Tryptophan 31 69 (Trp-31 Trp-69) in (Pa-11) snake, Pseudechis australis, were modified with N-bromosuccinimide (NBS) or 2-nitrophenylsulphenylchloride (NPSC1). NBS oxidized only Trp-31, whereas NPSC1 reacted both Trp-31 Trp-69. Treatment enzyme at various pH values resulted losses enzymic lethal activities. No protective effect on oxidation was observed by addition calcium ion (20 mM) lecithin (4 mM). The observations suggest that is exposed to surface molecule, composes a part lipid-water interface recognition site around active essential for activity. Calcium solution caused change ultraviolet spectrum native Pa-11. difference indicates charge typical tryptophan blue shift Ca2+-enzyme complex. Pa-11 showed smaller absorption Ca2+ ion. results show hypochromic induced upon binding due perturbation specific residue (Trp-31) which involved site. Dissociation constant, Kd, complex calculated be 3.4 × 10−4 M 8.0.