Notes: The authors studied the structure and function of Protein Kinase A (PKA) as a model for protein kinases. Two amino acids with contacts to other side chains, Thr197 and Ser338, were replaced with Alanine, expressed and purified from E. coli, and the enzymatic activity compared to that of wildtype PKA. The Kinase-Glo^® Luminescent Kinase Assay and the Kemptide peptide were used to determine the activities of the wildtype and mutant PKAs in the presence and absence of the known inhibitor, H7. (3290)