Phosphoenolpyruvate carboxykinase activity

Atkin, B.M., Utter, M.F. and Weinberg, M.B. (1979b), Pyruvate carboxylase and phosphoenolpyruvate carboxykinase activity in leukocytes and fibroblasts from a patient with pyruvate carboxylase deficiency. Pediatr. Res., 13,38. 

Gene activated Lipoprotein lipase fatty acid transporter protein adipocyte fatty acid binding protein acyl-CoA synthetase malic enzyme GLUT-4 glucose transporter phosphoenolpyruvate carboxykinase... 

Phosphoenolpyruvate carboxykinase (PEPCK) deficiency is distinctly rare and even more devastating clinically than deficiencies of glucose-6-phosphatase or fructose-1,6-bisphosphatase. PEPCK activity is almost equally distributed between a cytosolic form and a mitochondrial form. These two forms have similar molecular weights but differ by their kinetic and immunochemical properties. The cytosolic activity is responsive to fasting and various hormonal stimuli. Hypoglycemia is severe and intractable in the absence of PEPCK [12]. A young child with cytosolic PEPCK deficiency had severe cerebral atrophy, optic atrophy and fatty infiltration of liver and kidney. 

Uptake of Ca2+ into cells, or release of this ion from intracellular stores, is a major regulatory mechanism in many if not all cells (see Section E). Mn2+ activates phosphoenolpyruvate carboxykinase (Eq. 13-46) and maybe a regulator of gluconeogenesis.142 Iron controls the synthesis of ferritin and of transferrin receptors137 (Chapter 16). The specific metal ions present in many biological macromolecules are likely to participate in additional regulatory processes. 

Most cestodes which have been investigated, however, conform to the second category, type 2, which is characterised by a C02-fixation step. Carbohydrate is degraded to the level of PEP by glycolysis, the steps involved being similar to those in mammalian tissue. At this point, the enzymes pyruvate kinase and phosphoenolpyruvate carboxykinase (PEPCK) compete for available substrate and a branch-point occurs (Fig. 5.4). The relative activities of these two enzymes determine the fate of the PEP and the subsequent types and amounts of end-products formed (see below). 

Hadziosmanovic, A. Kravica, S. (1982). [The activity of phosphoenolpyruvate carboxykinase (PEPCK.) and pyruvate kinase (PK) in some parasitic helminths.] In Russian. Veterinarski Arkiv, 52 55-63. [HA/52/1493]... 

Biotin acts to induce glucokinase, phosphofructokinase, and pyruvate kinase (key enzymes of glycolysis), phosphoenolpyruvate carboxykinase (a key enzyme of gluconeogenesis), and holocarboxylase synthetase, acting via a cell-surface receptor linked to formation of cGMP and increased activity of RNA polymerase. The activity of holocarboxylase synthetase (Section 11.2.2) falls in experimental biotin deficiency and increases with a parallel increase in... 

Activity-levels of phosphoenolpyruvate carboxylase (EC 4.1.1.31, PEPC) and phosphoenolpyruvate carboxykinase (EC 4.1.1.49, PEPK) were examined with Rhodopseudomonas sp. No.7 grown photoanaerobically in an ethanol-bicarbonate and in an acetate medium. PEPC and PEPK were purified from cells grown under these conditions, and several characteristics of the enzymes were discussed in connection with photoheterotrophy of purple nonsulfur bacteria. 

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