O
OH
HOHO
AcHN
OO
OH
OHO
AcHNR
normal substrate type
O
OH
HOHO
AcHN
OF
OH
OHO
F
probe designed to trapintermediate
O
OH
HOHO
AcHN
OO
OH
OHO
AcHNR
normal substrate type
O
OH
HOHO
AcHN
OF
OH
OHO
F
probe designed to trapintermediate