The denaturation of rabbit muscle phosphorylase b by guanidinium chloride.
The denaturation of phosphorylase b by guanidinium chloride (GdnHCl) was studied. The enzyme is unusually sensitive to the denaturing agent, being more than 50% inactivated after incubation for 15 min in 0.1 M-GdnHCl. Full activity can be regained on dilution of the GdnHCl to 0.01 M, provided that the initial concentration of GdnHCl is less than 0.5 M. Studies of protein fluorescence, thiol-group reactivity, circular dichroism and absorption spectroscopy indicate that phosphorylase b undergoes slow structural changes in the range of GdnHCl concentrations from 0.5 to 0.8 M. The enzyme retains considerable folded structure even after 15 min incubation in 1 M-GdnHCl, but is rapidly and completely unfolded in 3 M-GdnHCl.
D000818:Animals; D002942:Circular Dichroism; D019791:Guanidine; D006146:Guanidines / Q000494:pharmacology*; D009132:Muscles / Q000201:enzymology*; D010763:Phosphorylase b / Q000378:metabolism*; D006005:Phosphorylases / Q000378:metabolism*; D011487:Protein Conformation; D011489:Protein Denaturation / Q000187:drug effects; D011817:Rabbits; D013053:Spectrophotometry; D013381:Subtilisins; D013438:Sulfhydryl Compounds; D014508:Urea
D006146:Guanidines; D013438:Sulfhydryl Compounds; D014508:Urea; D010763:Phosphorylase b; D006005:Phosphorylases; D013381:Subtilisins; D019791:Guanidine