III — Isolation and characterization of the α and β subunits of the platelet-activating glycoprotein from the venom of Crotalus durissus cascavella

It was concluded in a previous paper 13] that the high M_r platelet-activating glycoprotein isolated earlier from the venom of Crotalus durissus cascavella 11–12] has an hexameric structure of the α₃β₃ type involving two distinct subunits. Data reported here demonstrate that these two subunits are separable from each other by ion exchange chromatography under denaturating conditions, have similar M_rs (α = 12,540 et β = 13,770) and exist in a one to one ratio within the native molecule. Carbohydrate analysis indicated that they are both similarly glycosylated to a small extent. They have slightly different amino-acid compositions, a common N-terminal sequence up to the fifth residue and similar extinction coefficients at 280 nm. The native molecule has a calculated M_r of 78,930. Additional data demonstrated that convulxin from the venom of Crotalus durissus terrificus 3] is the same platelet-activating agent as the presently described platelet-activating glycoprotein (PAG) from the venom of Crotalus durissus cascavella 11–13].