Pyruvate Kinase PK

Synthetic peptide aptamers were used to bind to M2-PK and shift the isoenzyme into the low affinity dimeric conformation.228 A high throughput 

An opposite approach was followed by Jiang et al., who were looking for activators (instead of inhibitors) of M2-PK with the aim of returning cancer cells to a metabolic state characteristic of normal cells.234 

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Pyruvate kinase (PK) deficiency (MIM 255200) Presumably a variety of mutations in the gene for the R (red cell) isozyme of PK... 

Pyruvate kinase (PK) is one of the three postulated rate-controlling enzymes of glycolysis. The high-energy phosphate of phosphoenolpyruvate is transferred to ADP by this enzyme, which requires for its activity both monovalent and divalent cations. Enolpyruvate formed in this reaction is converted spontaneously to the keto form of pyruvate with the synthesis of one ATP molecule. PK has four isozymes in mammals M, M2, L, and R. The M2 type, which is considered to be the prototype, is the only form detected in early fetal tissues and is expressed in many adult tissues. This form is progressively replaced by the M( type in the skeletal muscle, heart, and brain by the L type in the liver and by the R type in red blood cells during development or differentiation (M26). The M, and M2 isozymes display Michaelis-Menten kinetics with respect to phosphoenolpyruvate. The Mj isozyme is not affected by fructose-1,6-diphosphate (F-1,6-DP) and the M2 is al-losterically activated by this compound. Type L and R exhibit cooperatively in... 

Fig. 4. Schematic representation of expression of the rat pyruvate kinase (PK) gene. Exons specific to each isozyme are indicated by marked boxes. The exons common to Mj- and M2-type PK and common to L- and R-type PK are shown by open boxes. CAAT, CAT box TATA, TATA box AATAAA, polyadenylation signal.

Deficiency of pyruvate kinase (PK) is the most common and well-characterized enzymatic deficiency involving the glycolytic pathway and causing hereditary he-... 

B30. B ianchi, P Terragna, C., Zappa, M., Alfinito, F and Zanella, A., Molecular characterization of L-PK gene in pyruvate kinase (PK) deficient Italian patients. Blood 84 (Suppl. 1), 14a (1994). 

K5. Kanno, H Fujii, H Hirono, A., Omine, M., and Miwa, S., Identical point mutations of the R-type pyruvate kinase (PK) cDNA found in unrelated PK variants associated with hereditary hemolytic anemia. Blood 79, 1347-1350 (1992). 

K13. Kanno, H Morimoto, M., Fujii, H., Kasugai, T., Noguchi, T., Kitamura, Y., and Miwa, S., Pri-mary structure of murine red cell type pyruvate kinase (PK) and molecular characterization of PK deficiency identified in the CBA strain. Blood 86,3205-3210 (1995). 

Na salts of ribonucleotide triphosphates (Roche or Sigma) bovine serum albumin RNase-free, 20 mg/ml (Roche) RNasin ribonuclease inhibitor, 40 U/ml (Promega) both bacteriophage T7 RNA polymerase and RNA Cap structure analog m7G(5/)ppp(5/)G are from BioLabs DNase-RNase-free (Roche) complete EDTA-free proteinase inhibitors cocktail (Roche) pyruvate kinase (PK) (Roche). 

Examples of substrate level phosphorylation are to be found in glycolysis. Phos-phoglycerate kinase (PGK) and pyruvate kinase (PK) catalyse the following reactions ... 

Muscle pyruvate kinase (PK) responds hyperbolically to its substrate, PEP, but the liver form of the enzyme responds sigmoidally. Fructose-1,6-bisphos-phate is an allosteric activator of liver pyruvate kinase, but it apparently has no effect on the muscle enzyme. 

Pyruvate kinase (PK) from F. hepatica closely resembles L-type PK from mammalian liver (Behm and Bryant, 1980). It shows cooperative kinetics with PEP, but in the presence of... 

Mizutani et al. [34] Acetic acid Wines Acetate kinase (AK), pyruvate kinase (PK) and pyruvate oxidase (PyOx)/on a photocross-linkable poly(vinyl alcohol) bearing stilbazolium group membrane Platinum electrode coated with poly (dimethylsilaxane)/-0.4 V vs. Ag/AgCl ... 

However, nucleoside diphosphates (NDP) are still expensive substrates, which can be obtained from much more cheaper nucleoside monophosphates (NMP). In this respect we have combined the SuSy-catalyzed cleavage of sucrose with the enzymatic formation of NDPs from NMPs catalyzed by nucleoside monophosphate kinase (NMPK, EC 2.7.4.4) or myokinase (MK, EC 2.7.4.3), including in situ regeneration of ATP with pyruvate kinase (PK, EC 2.7.1.40) (Fig. 20) [272]. Testing the substrate spectrum of four different kinases disclosed that none of them accepted dTMP as substrate [272], However, dUMP was well accepted by NMPK and dUDP-activated glucose could also substitute dTDP-activated glucose as precursor for the synthesis of activated deoxysugars (see below). The excellent enzyme stabilities under synthesis... 

Figure I. Composite diagram summarizing the roles of histidine imidazole groups at the active sites of the phosphotransferase enzymes creatine kinase (CrK), pyruvate kinase (PK), and adenylate...

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]... 

Figure 2. Hemoglobin, Maximal oxygen consumption (VO2 max), mitochondrial pyruvate kinase (PK), and endurance capacity of rats during seven days of iron repletion. Data from Ref. 29.

Figure 5-25. The conversion of pyruvate to phosphoenolpyruvate (PEP). Follow the diagram by starting with the precursors alanine and lactate. OAA = oxaloacetate FA = fatty acid TG = triacylglycerol PDH = pyruvate dehydrogenase PC = pyruvate carboxylase PEPCK = phosphoenolpyruvate PK = pyruvate kinase PK-P = phos- phorylated pyruvate kinase.

Pyruvate kinase (PK EC 2.7.1.40) catalyzes the conversion of phosphoenolpymvate to pyruvate with the concomitant generation of the second molecule of ATP in glycolysis. The activity of PK depends on red cell age. The younger the red cells, the higher the activity. 

The cascade begins with stoichiometric amounts of phosphoenolpyruvate (PEP), 8-allyl-A-acetyl lactosamine 120, NeuAc 1, and catalytic quantities of ATP and CMP. Initially, CMP is converted to CDP by nucleoside monophosphate kinase (NMK) in the presence of ATP. The CDP produced reacts with PEP under pyruvate kinase (PK) catalysis to form CTP. Next, CMP-NeuAc synthetase catalyzes the in situ formation of the sialyl donor from NeuAc and CTP. The pyrophosphate byproduct is decomposed to inorganic phosphate by inorganic pyrophosphatase (PPase). Subsequently, the a-2,6-sialyltransferase accomplishes the sialyation of the lactosamine acceptor 120 and produces the ttansferase inhibitor CMP as a by-product. The CMP concentrations are kept low by conversion to CDP, and in so doing the problem of product inhibition is minimized. The cycle afforded 21% of the sialylated ttisac-charide 121, which is remarkable considering the complexity of the system and number of synthetic steps that can be avoided. 

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