Role of Na+ and K+ in Enzyme Function

• Published in: Physiological reviews Vol. 86; no. 4; pp. 1049 - 1092
• Main Authors: Page, Michael J, Di Cera, Enrico
• Format: Journal Article
• Language: English
• Published: United States Am Physiological Soc 01.10.2006; American Physiological Society
• Subjects: Analysis; Animals; Binding Sites - physiology; Catalysis; Enzyme Activation - physiology; Enzyme kinetics; Enzymes - chemistry; Enzymes - metabolism; Humans; Metals; Potassium - metabolism; Proteins; Sodium - metabolism; Studies
• ISSN: 0031-9333; 1522-1210
• DOI: 10.1152/physrev.00008.2006

Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri Metal complexation is a key mediator or modifier of enzyme structure and function. In addition to divalent and polyvalent metals, group IA metals Na + and K + play important and specific roles that assist function of biological macromolecules. We examine the diversity of monovalent cation (M + )-activated enzymes by first comparing coordination in small molecules followed by a discussion of theoretical and practical aspects. Select examples of enzymes that utilize M + as a cofactor (type I) or allosteric effector (type II) illustrate the structural basis of activation by Na + and K + , along with unexpected connections with ion transporters. Kinetic expressions are derived for the analysis of type I and type II activation. In conclusion, we address evolutionary implications of Na + binding in the trypsin-like proteases of vertebrate blood coagulation. From this analysis, M + complexation has the potential to be an efficient regulator of enzyme catalysis and stability and offers novel strategies for protein engineering to improve enzyme function.