G Explain the results obtained with the S to E mutant glycogen phosphorylase. The S to E mutant would mimic the phosphorylase in the T state. The reduced response is due to blockage of phosphorylase kinase’s catalytic site. Glutamate's negatively charged R group mimics a phosphorylated serine residue. The Vmax is reduced because the carboxyl group is smaller and less charged than a phosphate group. The S to E mutant would mimic the phosphorylase in the R state. The reduced response is due to blockage of phosphorylase kinase’s catalytic site. Glutamate's positively charged R group mimics the phosphoryl group on serine. There is a reduced response because the carboxyl group is smaller and less charged than the phosphate.