Topic
Pyruvate kinase
About: Pyruvate kinase is a research topic. Over the lifetime, 5683 publications have been published within this topic receiving 180020 citations. The topic is also known as: ATP:pyruvate 2-O-phosphotransferase & phosphoenolpyruvate kinase.
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TL;DR: 5-Oxo-L-prolinase, an enzyme that catalyzes the conversion of 5-oxo- L-proline to L-glutamate coupled with the cleavage of ATP to ADP and Pi, has been purified about 1600-fold from rat kidney.
59 citations
TL;DR: The cytosolically located pyruvate kinase of T. brucei lacks the specific features found in the majority of the glycolytic enzymes of this organism that are sequestered in a microbody-like organelle, the glycosome.
Abstract: In Trypanosoma brucei (stock 427) genes encoding the glycolytic enzyme pyruvate kinase are present on two homologous chromosomes We have cloned and characterized one of the alleles Two large, tandemly arranged open reading frames were found, each coding for a pyruvate kinase polypeptide of 498 amino acids The gene sequences differ at 15 positions, resulting in five amino acid substitutions The calculated molecular masses of the polypeptides are 54,378 Da and 54,363 Da These values are somewhat smaller than those reported for the subunit molecular mass of the purified protein, which is 57-59 kDa However, in vitro translation of the DNA region corresponding to the open reading frame, and translation of the RNA in a wheat-germ lysate, yielded a product that comigrated exactly with the native polypeptide in SDS/PAGE The overall identity between the sequences of the trypanosomal enzyme and the enzymes from other sources is 41-51% The conserved residues are not equally distributed over the polypeptide The primary structure of domains A and, to a lesser extent, B, which constitute the active site, are rather well conserved In contrast, the sequence of domain C, which supposedly is involved in the regulation of the enzyme activity, is much more variable The cytosolically located pyruvate kinase of T brucei lacks the specific features found in the majority of the glycolytic enzymes of this organism that are sequestered in a microbody-like organelle, the glycosome It has neither a relatively high subunit molecular mass, due to unique insertions or terminal extensions, nor a high excess of positively charged amino acids The polypeptide is shorter than that of most other pyruvate kinases and the calculated net charge is only +3
59 citations
TL;DR: The binding of various regulatory ligands and substrates to the fructose bisphosphate activated pyruvate kinase from Escherichia coli has been studied at equilibrium on the basis of a two-site model, where the substrate and fructose bisPhosphate bind to one conformation and the inhibitors to the other.
Abstract: The binding of various regulatory ligands and substrates to the fructose bisphosphate activated pyruvate kinase from Escherichia coli has been studied at equilibrium The allosteric activator, fructose bisphosphate, and the substrate phosphoenolypyruvate bind in a cooperative manner to the enzyme There is one site for each of these ligands per monomer In the presence of fructose bisphosphate the binding of phosphoenolpyruvate follows an absorption isotherm, ie, all homotropic interactions of the substrate are lost In reciprocal experiments, however, both phosphoenolpyruvate and KCl are required in order to facilitate binding of the activator The allosteric inhibitors of pyruvate kinase, ATP, succinyl-CoA, and GTP compete on the enzyme surface with the binding of the activator, fructose bisphosphate, Inhibitor pairs such as ATP and succinyl-CoA together bring about not cooperative but only additive inhibition of the binding of the activator The nucleotide substrate GDP and the allosteric inhibitor GTP have in contrast to the activator two seemingly noninteracting sites on each monomer In the saturating presence of fructose bisphosphate, however, binding of GDP and possibly also of GTP occurs at only one site on each monomer Magnesium ions inhibit binding of GDP and GTP KCl which is an activator of the enzyme along with its analogues, such as ammonia, thallium, rubidium, etc, enhances the binding of phosphoenolpyruvate but not of the nucleotides or fructose bisphosphate The data are analyzed on the basis of a two-site model, where the substrate and fructose bisphosphate bind to one conformation and the inhibitors to the other
59 citations
TL;DR: Purification of four isozymes of pyruvate kinase L, M1, M2 and R was much improved to give good yields by affinity elution chromatography and Amino acid analyses showed that the compositions of types L and R, and of types M1 and M2, respectively, were very similar.
59 citations
TL;DR: Studies with the partially purified erythrocytic guanylate kinase showed that GMP, dGMP, 8-azaGMP and IMP serve as substrates while UMP, CMP and 6-thioIMP do not.
59 citations