G lu 3 5 ) ▁and ▁as part ate ▁ 5 2 ▁( A sp 5 2 ) ▁have ▁been ▁found ▁to ▁be ▁critical ▁to ▁the ▁activity ▁of ▁this ▁en zym e . ▁G lu 3 5 ▁acts ▁as ▁a ▁pro ton ▁don or ▁to ▁the ▁g ly cos id ic ▁bond , ▁cle aving ▁the ▁C - O ▁bond ▁in ▁the ▁substr ate , ▁whereas ▁Asp 5 2 ▁acts ▁as ▁a ▁nucle oph ile ▁to ▁generate ▁a ▁g ly cos yl ▁en zym e ▁intermediate . ▁The ▁G lu 3 5 ▁react s ▁with ▁water ▁to ▁form ▁hydro x yl ▁ion , ▁a ▁stronger ▁nucle oph ile ▁than ▁water , ▁which ▁then ▁attacks ▁the ▁g ly cos yl ▁en zym e ▁intermediate , ▁to ▁give ▁the ▁product ▁of ▁hydro ly s is ▁and ▁leaving ▁the ▁en zym e ▁un changed . ▁This ▁c oval ent ▁mechanism ▁was ▁named ▁after ▁K osh land , ▁who ▁first ▁proposed ▁this ▁type ▁of ▁mechanism . ▁ ▁More ▁recently , ▁quantum ▁mechan ics / ▁mole cular ▁mechan ics ▁( Q M / MM ) ▁mole cular ▁dynamics ▁simulations ▁have ▁been ▁using ▁the ▁cry stal ▁of ▁HE W L ▁and ▁predict ▁the ▁existence ▁of ▁a ▁c oval ent ▁intermediate . ▁ ▁Ev idence ▁for ▁the ▁E SI - MS ▁and ▁X - ray ▁structures ▁indicate ▁the ▁existence ▁of ▁c oval ent ▁intermediate , ▁but ▁primarily ▁rely ▁on ▁using ▁a ▁less ▁active ▁mut ant ▁or ▁non - native ▁substr ate . ▁Thus , ▁Q M / MM ▁mole cular