Characterization Of The pH And Temperature Stability Of Convulxin Using Dynamic Light Scattering.

Viçoti, M. M.;  Zela, S.P.; Murakami, M.T.; Arni, R.K.

Departamento de Física, IBILCE/UNESP, São José do Rio Preto, São Paulo, Brasil.

Convulxin (CVX) is a heterotetrameric C-type lectin isolated from the venom of the Brazilian Rattlesnake Crotalus durissus terrificus, which causes cardiovascular and respiratory disturbances and is a powerful platelet activator which functions via binding and clustering of GPVI-receptors. CVX utilizes a Ca²⁺ dependent mechanism which is independent of galactose or mannose, fibrinogen and ADP. The crystal structure of CVX indicates that it exists under physiological conditions as a disulfide linked cyclic tetramer which leads to the formation of a large solvent channel with a diameter of 60 Å. We have undertaken a dynamic light scattering study to determine the pH and temperature stability of this tetramer and to characterize the formation of higher order multimers.

CVX was purified from crude venom and the stability was followed by dynamic light scattering (DYNAPRO 801-Protein Solutons) equipped with a temperature controlled cell. The pH was varied between 3.4 to 10.6 and the temperature was varied from 20 to 70ºC in steps of 5ºC. This data was analyzed and indicated that the tetrameric state of CVX was most stable at pH 5.4 in all ranges of temperature analyzed.

This research was supported by grants from FAPESP, CNPq and CAPES.

Correspondence to: sandropz@bol.com.br