Evidence of a novel role for monovalent cations in pyruvate kinase catalysis

1976 ◽  
Vol 54 (5) ◽  
pp. 393-397 ◽  
Author(s):  
James L. Robinson
Keyword(s):  
Pyruvate Kinase ◽  
Divalent Cation ◽  
Monovalent Cation ◽  
Monovalent Cations ◽  
Forward Reaction ◽  
Cation Concentration ◽  
High Concentrations ◽  
Reaction Inhibition

In the pyruvate kinase (EC 2.7. 1.40) reaction, the complete enzyme–products complex consists of enzyme, pyruvate, ATP, a divalent cation, and a monovalent cation, usually K+. The dissociation of this, complex can be slow permitting reversible enolization of pyruvate in this complex during the course of the forward reaction. High concentrations of each component in the enzyme–products complex inhibits the forward reaction, but only elevated concentrations of the monovalent cation decrease the net rate of product dissociation relative to that of pyruvate enolization. This result indicates that the monovalent cation can be the first component released from the enzyme–products complex and that the presence of an inhibiting monovalent cation concentration leads to re-formation of the complete complex, which is necessary for pyruvate enolization. The evidence suggests that the monovalent cation can bind and release with each turnover of the enzyme. While the data do not permit the conclusion that first release of monovalent cation is the exclusive pathway for dissociation of the enzyme–products complex, no other component once released can reassociate rapidly enough to form a complete complex during the forward reaction. Inhibition by these components must be attributed to the formation of abortive complexes.

Cell-associated cations of the moderate halophile Micrococcus varians ssp. halophilus grown in media of high concentrations of LiCl, NaCl, KCl, RbCl, or CsCl

1982 ◽  
Vol 28 (2) ◽  
pp. 155-161 ◽  
Author(s):  
Masahiro Kamekura ◽  
Hiroshi Onishi
Keyword(s):  
Exponential Phase ◽  
Monovalent Cations ◽  
Complex Media ◽  
Moderate Halophile ◽  
Cation Concentration ◽  
Equivalent Concentration ◽  
High Concentrations

Micrococcus varians ssp. halophilus ATCC 21971 showed abundant growth in complex media containing 1 M NaCl, NaBr, NaI, NaNO3, Na2SO4, KCl, KBr, KI, or KNO3, and 2 M RbCl or RbBr at 30 °C.Spontaneous mutants were isolated which were able to grow in a medium of 1.5 M LiCl (strain Li-5) or 2.5 M CsCl (strain Cs-7-Cs). Determination of cell-associated cation concentration at the exponential phase of growth showed that the cells contained monovalent cations of almost equivalent concentration as that in the medium: 0.570 m Li+ + 0.951 m Na+ in 1.5 M LiCl grown cells; 2.88 m Na+ in 3.0 M NaCl grown cells; 2.66 m K+ in 3.0 M KCl grown cells; 1.57 m Rb+ in 2.0 M RbCl grown cells; 1.44 m Cs+ in 1.5 M CsCl grown cells.

X-ray microanalysis of HeLa S3 cells. II. Analysis of elemental levels during the cell cycle

1983 ◽  
Vol 62 (1) ◽  
pp. 339-350
Author(s):  
A. Warley ◽  
J. Stephen ◽  
A. Hockaday ◽  
T.C. Appleton
Keyword(s):  
Cell Cycle ◽  
Monovalent Cation ◽  
The Other ◽  
G1 Phase ◽  
Sodium Potassium ◽  
X Ray ◽  
Cation Concentration ◽  
Cell Compartments ◽  
Hela S3 ◽  
Hela S3 Cells

HeLa S3 cells were synchronized using hydroxyurea. Cryoultramicrotomy and X-ray microanalysis were used to study changes occurring in concentrations of elements during the cell cycle of the synchronized cells. Three subcellular compartments were studied: cytoplasm, nucleus and nucleolus. Potassium concentrations showed little fluctuation in all of the cell compartments during the cell cycle. Sodium concentrations increased during S. and M phases, returning to lower levels in the G1 phase. Chlorine concentrations were highest during the S and G2 phases. At all stages of the cell cycle respective concentrations of potassium, sodium, sulphur and chlorine were similar in the cytoplasm and nucleus. Concentrations of phosphorus increased in the nucleus during S, G2 and M, and also showed fluctuations in the nucleolus during the cycle; these were not seen in the cytoplasm. In S, M and M/G1 sodium concentrations were highest in the nucleolus compared with the other compartments. In the cytoplasm these changes resulted in an increase in total monovalent cation concentration (i.e. sodium + potassium) during S, G2 and M, which returned to base levels after mitosis. This increase in monovalent cation concentration is due almost entirely to the increase in sodium, with little change occurring in the concentration of potassium.

scholarly journals The role of monovalent cations in the ATPase reaction of DNA gyrase

2015 ◽  
Vol 71 (4) ◽  
pp. 996-1005 ◽  
Author(s):  
Stephen James Hearnshaw ◽  
Terence Tsz-Hong Chung ◽  
Clare Elizabeth Mary Stevenson ◽  
Anthony Maxwell ◽  
David Mark Lawson
Keyword(s):  
Escherichia Coli ◽  
Binding Sites ◽  
Dna Gyrase ◽  
Monovalent Cation ◽  
Cation Binding ◽  
Monovalent Cations ◽  
Atpase Domain ◽  
Atpase Reaction ◽  
Resolution Structure

Four new crystal structures of the ATPase domain of the GyrB subunit ofEscherichia coliDNA gyrase have been determined. One of these, solved in the presence of K+, is the highest resolution structure reported so far for this domain and, in conjunction with the three other structures, reveals new insights into the function of this domain. Evidence is provided for the existence of two monovalent cation-binding sites: site 1, which preferentially binds a K+ion that interacts directly with the α-phosphate of ATP, and site 2, which preferentially binds an Na+ion and the functional significance of which is not clear. The crystallographic data are corroborated by ATPase data, and the structures are compared with those of homologues to investigate the broader conservation of these sites.

THE CULTURE OF DUNALIELLA TERTIOLECTA BUTCHER—A EURYHALINE ORGANISM

1960 ◽  
Vol 6 (3) ◽  
pp. 367-379 ◽  
Author(s):  
Jack McLachlan
Keyword(s):  
Sodium Chloride ◽  
Sea Water ◽  
Dunaliella Tertiolecta ◽  
Monovalent Cations ◽  
Minimum Requirement ◽  
Fresh Waters ◽  
Wide Range ◽  
Calcium And Magnesium ◽  
Low Levels ◽  
High Concentrations

Dunaliella tertiolecta Butcher was found to be a euryhaline organism which grew at salinities ranging from 3.75 to 120‰. All the conservative elements of sea water, with the exception of chlorine, were found necessary for growth of the alga. The minimum requirement for sodium was much greater than that for any other element, and it was not possible to substitute other monovalent cations for the minimum requirement. Also, the alga could tolerate high concentrations of sodium chloride. The potassium and sulphur concentrations of the medium could be reduced to very low levels. Dunaliella could also tolerate high concentrations of these two elements. The addition of lithium to the medium inhibited the growth of the alga. High concentrations of sodium could partially eliminate the inhibition due to lithium. The minimum concentrations of calcium and magnesium necessary for growth approached the concentrations found in fresh waters. Calcium and magnesium were inhibitory at high concentrations, but the inhibition at high concentrations could be prevented if a Mg/Ca ratio of 4 was maintained over a wide range of concentrations in the medium.

scholarly journals DNA A-tracts Are Not Curved in Solutions Containing High Concentrations of Monovalent Cations

Biochemistry ◽  
2013 ◽  
Vol 52 (24) ◽  
pp. 4138-4148 ◽  
Author(s):  
Earle Stellwagen ◽  
Justin P. Peters ◽  
L. James Maher ◽  
Nancy C. Stellwagen
Keyword(s):  
Monovalent Cations ◽  
High Concentrations
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