3-Phosphoglycerate phosphatase

Fig. 1. Main routes involved in the synthesis and interconversion of glycine and serine in plants. The various steps are numbered, and the necessary enzymes are as follows 1, glycolate oxidase, E.C. 1.1.3.1 2, aminotransferases, serine, E.C. 2.6.1.45, and glutamate, E.C. 2.6.1.4, glyoxylate aminotransferases 3, enzyme complex in mitochondria (see Fig. 2) 4, serine-glyoxylate aminotransferase, E.C. 2.6.1.45 5, glycerate dehydrogenase, E.C. 1.1.1.29 6, glycerate kinase E.C. 2.7.1.31 7, D-3-phosphoglycerate phosphatase, E.C. 3.1.3.38 8, d-3-phosphoglycerate dehydrogenase, E.C. 1.1.1.95 9, phosphoserine aminotransferase, E.C. 2.6.1.52 10, phosphoserine phosphatase, E.C. 3.1.3.3 11, serine hydroxymethyltransferase E.C. 2.1.2.1 12, nonenzymatic decarboxylation 13, formyl tetrahydrofolate synthetase, E.C. 6.3.4.3 14, isocitrate iyase, E.C. 4.1.3.1.

Fig. 4. Biosynthesis of mannosyiglycerate in Rhodothermus marinus. The reaction scheme was proposed based on measurements of enzyme activities in cmde cell extracts and C-labeling experiments. The numbers refer to the following enzymes 1, mannosyiglycerate synthase 2, mannosyl-3-phosphoglycerate synthase 3, mannosyl-3-phosphoglycerate phosphatase. Data from L. O. Martins, N. Empadinhas, J. D. Marugg, C. Miguel, C. Ferreira, M. S. da Costa, and H. Santos, J. Biol. Chem. 274,35407 (1999).

The widespread occurrence of a specific phosphoglycerate phosphatase in leaves (Randall et al., 1971) makes D-glyceric acid available from photo-... 

Bisphosphoglycerate is synthesized from 1,3-bisphosphoglycerate, a reaction catalyzed by 2.3-bisphosphoglycerate synthase. The enzyme 2,3-bisphosphoglycerate phosphatase catalyzes the hydrolysis of 2,3-bisphosphoglycerate to 3-phosphoglycerate. 

To date phosphorothioates have with very few exceptions, been found to be acceptable substrates for stereochemical experiments. They generally react more slowly than naturally occurring substrates, from 1 to 10% of the rates for phosphates in many cases of phosphotransferases and 10 to 100% of the normal rates in the cases of nucleotidyltransferases acting on a-thionucleotides. In a very few cases, notably alkaline phosphatase and phosphoglycerate mutase, phosphorothioates are unacceptable as substrates, necessitating the development of methods for synthesiz-... 

Despite the broad utility of chiral phosphorothioates, certain enzymes, such as alkaline phosphatase and phosphoglycerate mutase, do not accept phosphorothioates as substrates. Stereochemical studies of these enzymes awaited the development of methods to synthesize and assign configurations to chiral phosphates. Chiral [l60, l70,180]phosphomonoesters and [l8OJphosphodiesters have been elegantly... 

Figure 2.5 Gluconeogenesis is the reversal of glycolysis, attained through the use of four unique enzymes glucose-6-phosphatase (A), fructose-1,6-bisphosphatase (5), PEP carboxykinase (6) and pyruvate carboxylase (7). Although phosphoglycerate kinase is shared with glycolysis, in gluconeogenesis this reaction requires the input of ATP.

Examination of the first partial reaction reveals that the mutase functions as a phosphatase—it converts 2,3-bisphosphoglycerate into 2-phosphoglycerate. However, the phosphoryl group remains linked to the enzyme. This phosphoryl group is then transferred to 3-phosphoglycerate to reform 2,3-bisphosphoglycerate. 

The 3-carbon intermediate compound 3-phosphoglycerate is also of interest in nutrition, because it is a precursor to serine. In the body, conversion occurs as follows the 2-hydroxyl group is oxidized to a 2-ketogroup, which when converted to a 2-amine yields phosphoserine. This conversion is catalyzed by a vitamin Bfi-dependent enzyme. Finally, hydrolysis of the 3-phosphate by a phosphatase yields serine. 

The mutase then functions as a phosphatase it converts 2,3-bisphosphoglycerate into 2-phosphoglycerate. The mutase retains the phosphoryl group to regenerate the modified histidine. 

Fig. 1 Three-dimensional representation of phosphoglycerate mutase left) [47] and rat prostatic acid phosphatase (right). Based on Schneider et al. [1]...

Serine is synthesized in a direct pathway from glycerate-3-phosphate that involves dehydrogenation, transamination, and hydrolysis by a phosphatase (Figure 14.6). Cellular serine concentration controls the pathway through feedback inhibition of phosphoglycerate dehydrogenase and phosphoserine phosphatase. The latter enzyme catalyzes the only irreversible step in the pathway. 

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