Information AboutBeta-galactosidase |
| CATEGORIES ABOUT BETA-GALACTOSIDASE | |
| ec 3.2.1 | |
| hydrolases | |
| enzymes | |
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STRUCTURE The 1,023 Amino Acid s of ''E. coli'' Beta-galactosidase were first sequenced in 1970 1. Four such chains comprise the Protein , which was discovered to be a 464- KDa Tetramer with 222-point Symmetry twenty-four years later. Each unit of beta-galactosidase consists of five domains, the third of which is an active site2. REACTION The active site of Beta-galactosidase catalyzes the hydrolysis of its Disaccharide substrate via "shallow" and "deep" binding. Optimal activity of the enzyme requires monovalent Sodium Ion s (Na+) as well as divalent Magnesium ions (Mg2+). The beta-linkage of the substrate is cleaved by a terminal Carboxyl group on the side chain of a Glutamic Acid . In ''E. coli'', the Nucleophile in the Substitution reaction was thought to be the Glu-4613; it is now known that Glu-461 is an Acid catalyst. Glu-537 is the actual nucleophile4, binding to a galactosyl intermdiate. In Human s, the nucleophile of the hydrolysis reaction is Glu-2685. BIOLOGY Beta-galactosidase is an essential enzyme in the human body. Deficiencies in the protein result can result in Galactosialidosis or Morquio B Syndrome . In '' E. Coli '', beta-galcatosidase is produced by activation of the ''lac Z'' operon. REFERENCES |
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