Penaeus vannamei protease activating mechanism of sulfhydryl reducing compounds

For the very first time, protease enzyme from Penaeus vannamei was investigated for its activation with thiol reductant compounds. The mechanism by which sulfhydryl reductant compounds enhances the activity of P. vannamei protease still remains unclear. In this study, it was discovered that thiol-reactive compounds increase P. vannamei protease activity by a factor of about 4 with increasing V_max and decreasing Km parameters. Moreover, the reaction is an S_N2-type that does not require the initial binding of the thiol group of these compounds to the enzyme. Additionally, k₂ increased appreciably with increasing concentration of sulfhydryl reductant compounds. The linearity of this plot indicates that k₁ is unaffected by the addition of thiol compounds. Hence, the observed effect of thiol compounds on K_m seems to be due to an increase in k₂. These results suggest that the activation mechanism of P. vannamei protease almost certainly takes place by an S_N2 reaction mechanism.