3- Phosphoglycerate dehydrogenase

Schuller, D. J., Grant, G. A., and Banaszak, L.J. (1995). The allosteric ligand site in the Vmax-type cooperative enzyme phosphoglycerate dehydrogenase. Nat. Struct. Biol. 2, 69-76. 

One excellent example of a Emax-type allosteric enzyme is Escherichia coli phosphoglycerate dehydrogenase (PGDH), a tetramer of identical subunits that catalyzes the formation of D-3-phosphohydroxypyruvate from D-3-phosphoglycerate in a reaction that uses NAD+ as a redox cofactor. This regulatory enzyme is allosteri-cally controlled by serine. All available information suggests that the effects on the for substrate are minor... 

Figure 24.21. Structure of 3-Phosphoglycerate Dehydrogenase. This enzyme, which catalyzes the committed step in the serine biosynthetic pathway, includes a serine-binding regulatory domain. Serine binding to this domain reduces the activity of the enzyme.

Figure 24.23. A Recurring Regulatory Domain. The regulatory domain formed by two subunits of 3-phosphoglycerate dehydrogenase is structurally related to the single-chain regulatory domain of threonine deaminase. Sequence analyses have revealed this amino acid-binding regulatory domain to be present in other enzymes as well.

Effects on muscle enzymes. In addition to mentioned above 5 -lipoxigenase, tirosine hydroxilase and NO-synthase, some other enzymes are known to be affected by carnosine. Carnosine (as well as histidine) protects 3-phosphoglycerate dehydrogenase from heavy metals [6] and activates phosphorylase a and b (the former— in the acidic pH areas) [77], Stimulation of the over-all glycolytic process by the dipeptides is usually explained by their pH-buflfering capacity and protection of individual glycolytic enzymes from contaminations of heavy metals [78]. 

IV The ser A gene (coding for phosphoglycerate dehydrogenase ) was amplified using a plasmid vector with strain III... 

Phosphoglycerate dehydrogenase catalyzes the conversion of 3-phosphoglycerate to 3-phosphohydroxypyruvate, an intermediate in the biosynthesis of serine. 

The precursor of cysteine is the amino acid serine. The biosyntiiesis of this amino acid is mainly regulated by feedback-inhibition. The enzyme, which is sensitive to higher serine concentrations in the cell is the 3-phosphoglycerate dehydrogenase. The serA, coding for this enzyme, was subjected to a mutagenesis procedure to obtain mutants with a reduced feedback inhibition but... 

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. 

Consider first three "homo-polymeric" enzymes, all shown to involve allosteric effects malate dehydrogenase, 3-phosphoglycerate dehydrogenase, and glutamate dehydrogenase. Malate dehydrogenase (Fig. 9.8), a dimer, has a single interface (29) 3-phospho-... 

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