The change in kcat between ph 6 and ph 7 must involve the change in k c a t between p h 6 and p h 7 must involve blank of a proton in the active site. the best candidate is blank. the increase in k m at higher p h must involve a change in the binding site. the group involved is probably the blank at i l e 16, created by the cleavage that activates chymotrypsin. of a proton in the active site. the best candidate is the change in k c a t between p h 6 and p h 7 must involve blank of a proton in the active site. the best candidate is blank. the increase in k m at higher p h must involve a change in the binding site. the group involved is probably the blank at i l e 16, created by the cleavage that activates chymotrypsin.. the increase in km at higher ph must involve a change in the binding site. the group involved is probably the the change in k c a t between p h 6 and p h 7 must involve blank of a proton in the active site. the best candidate is blank. the increase in k m at higher p h must involve a change in the binding site. the group involved is probably the blank at i l e 16, created by the cleavage that activates chymotrypsin. at ile 16, created by the cleavage that activates chymotrypsin.