▁changes ▁in ▁their ▁active ▁site . ▁ ▁In ▁ 1 9 6 8 ▁he ▁published ▁a ▁paper ▁on ▁the ▁prote as omic ▁dig est ive ▁en zym e ▁ch ym ot ry ps in : ▁“ Con formation ▁and ▁Activity ▁of ▁Ch ym ot ry ps in : ▁the ▁p H - Dep endant , ▁Sub str ate - Ind u ced ▁Pro ton ▁U pt ake .”   ▁His ▁find ings ▁summar ized ▁the ▁conform ational ▁change ▁that ▁ch ym ot ry ps in ▁under go es ▁in ▁reaction ▁to ▁a ▁change ▁in ▁p H ▁and ▁how ▁it ▁leads ▁to ▁a ▁pro ton ▁u pt ake . ▁ ▁He ▁detailed ▁the ▁k inet ics ▁and ▁determined ▁the ▁p K ▁of ▁the ▁en zym e . ▁ ▁H ess ▁used ▁his ▁phot ol ysis ▁technique ▁to ▁continue ▁to ▁study ▁ne uro trans mit ters .   ▁It ▁allowed ▁for ▁the ▁visual ization ▁of ▁the ▁g ly c ine ▁re ceptor ▁channels ▁and ▁the ▁blocking ▁of ▁the ▁use ▁of ▁the ▁car box yl ▁group ▁in ▁ne uro trans mit ters .   ▁He ▁published ▁his ▁results ▁in ▁ 1 9 9 3 ▁in ▁the ▁article : ▁“ Ph ot ol ysis ▁of ▁a ▁Prote ct ing ▁Group ▁for ▁the ▁Car box yl ▁Function ▁of ▁Ne uro trans mit ters ▁within ▁ 3 μ s ▁and ▁with ▁Product ▁Quant um ▁Y ield ▁of ▁ 0 . 2 ,” ▁where ▁he ▁also ▁discussed ▁the ▁effects ▁and ▁uses ▁of ▁the ▁phot ol ysis ▁technique . ▁ ▁He