What is the role of Mg++,Zn++ in various steps of glycolysis ?
Answers
Answer:
Cofactors are often classified as inorganic substances that are required for, or increase the rate of, catalysis.
Examples of some enzymes that require metal ions as cofactors is shown in the table below
cofactor
enzyme or protein
Zn++
carbonic anhydrase
Zn++
alcohol dehydrogenase
Fe+++ or Fe++
cytochromes, hemoglobin
Fe+++ or Fe++
ferredoxin
Cu++ or Cu+
cytochrome oxidase
K+ and Mg++
pyruvate phosphokinase
OR
magnesium is an important coherent controller of glycolysis and the Krebs cycle. Many of the glycolytic enzymes are sensitive to Mg2+. The most important effect is due to MgATP2-being a cofactor for a number of these enzymes while other chelation forms are inactive or inhibitory. The means by which Mg2+ and Mg2+ chelates of adenine nucleotides regulate the most important glycolytic enzymes--hexokinase, phosphofructokinase, aldolase, phosphoglycerate kinase, and pyruvate kinase--are described in detail. Creatine kinase, which is important in energy metabolism and highly sensitive to both metal ions and pH, is also discussed. It is necessary to properly control the composition of assay mixtures (particularly with regard to metal ions) in order to determine what actually regulates the activity of an enzyme OR