BIO203H5 Chapter Notes - Chapter 4: Atp Hydrolysis, Transfer Rna, Reading Frame
Document Summary
Enzymes are not only regulated by the binding of small molecules. Regulation a protein activity by protein phosphorylation; attaching a phosphate group covalently to one of it"s amino acids side chains. Each phosphate group carries two negative charges, the enzyme-catalyzed addition of phosphate group to a protein can cause major conformation change (by attracting a cluster of positively charged amino acid side chains. ) This conformational change has an affect on the binding of ligands elsewhere on the protein structure thus altering the protein"s activity. Removal of the phosphate group by a second enzyme returns the protein to its original conformation and restores its initial activity. Protein phosphorylation is a reversible process and it controls the activity of many types of protein in eukaryotic cells. More than one third of the 10,000 or so proteins in a typical mammalian cell appear to be phosphorylated at any minute.
