NOS3 and endothelial dysfunction: Furthermore, Golser et al. [27] reported that Asp298 variant purified from a yeast expression system does not influence enzyme function and can not explain endothelial dysfunction associated with this polymorphism, while Dosenko et al. [28] demonstrated that eNOS activity in isolated human platelets from 894T/T homozygotes was not significantly lower than in normal homozygotes.