Phosphoryl transfer from o-carboxyphenyl phosphate to tri(hydroxymethyl)-aminomethane catalysed by alkaline phosphatase from E. coli

Abstract

1. 1. A pH optimum of 8.1 and a weak ionic strength dependence were found in Tris buffer. 2. 2. A light rate enhancement was established with an increase in Tris. 3. 3. Transferase activity to Tris has been tested by ratios measurement of the products at different times and Tris concentrations. 4. 4. Transphosphorylation is not pH-dependent. 5. 5. The release of o-carboxyphenol and Tris-phosphate was Tris-dependent with a maximum at 1.0 M. A decreasing curve was found for phosphate. 6. 6. Lineweaver-Burk plot was maintained biphasic in Tris at high ionic strength, opposed to barbital buffer. 7. 7. These results suggest that phosphorylation of the enzyme is not the only controlling step in o-carboxyphenyl phosphate hydrolysis. New effects of Tris are also proposed. © 1980.