Sulfhydryl groups of rabbit muscle glycogen phosphorylase b. Reaction with dinitrophenylating agents
Biochemistry 7(6): 2106-2115
ISSN/ISBN: 0006-2960 PMID: 4873171 DOI: 10.1021/bi00846a013
The reaction of glycogen phosphorylase b from rabbit muscle with fluorodinitrobenzene (FDNB) and chlorodinitrobenzene (CDNB) was studied by following the absorbance at 335 m Both reagents react rapidly with 4 sulfhydryl groups and much more slowly with other sulfhydryl, amino, and phenolic hydroxyl groups. The reacting groups were identified from the ultraviolet absorption spectrum of the dinitrophenyl (DNP) protein and by means of the isotope dilution method using 14C-labeled reagents. Substrates and adenosine 5monophosphate (AMP) have little inhibitory effect on the reaction of the enzyme with FDNB; however AMP has a distinct, though small, protective effect upon the reactive sulfhydryl groups against CDNB.