degradation of the penicillin g derived from ( 2r,3r ) - [ u-14c,2,3-3h2 ] cysteine hydrochloride has indicated that in fact about 87 % of the original c-3 tritium of cysteine is retained at c-5 of penicillin g .
C0724565
cysteine hydrochloride
C0010654
cysteine