scholarly journals Pyruvate kinase variants of the Alaskan king-crab. Evidence for a temperature-dependent interconversion between two forms having distinct and adaptive kinetic properties

1969 ◽  
Vol 114 (2) ◽  
pp. 237-241 ◽  
Author(s):  
George N. Somero
Keyword(s):  
Pyruvate Kinase ◽  
Kinetic Properties ◽  
Protein Species ◽  
Temperature Dependent ◽  
King Crab ◽  
Temperature Changes ◽  
Sigmoidal Kinetics ◽  
Opposite Situation ◽  
Pyruvate Kinases ◽  
Substrate Concentrations

1. Pyruvate kinase of Alaskan king-crab leg muscle exists in two kinetically distinct forms, each of which displays a different temperature-dependence in the Km for phosphoenolpyruvate. 2. A ‘cold’ variant of the enzyme has hyperbolic kinetics and exhibits a minimal Km for substrate at 5°. At physiological concentrations of phosphoenolpyruvate the ‘cold’ enzyme is active only below 10°. A ‘warm’ pyruvate kinase has a minimal Km for substrate at about 12°. This enzyme displays sigmoidal kinetics and is likely to be inactive, at physiological substrate concentrations, at temperatures below 9°. 3. The combined activities of these two pyruvate kinases yield highly temperature-independent rates of catalysis, at physiological substrate concentrations, over the range of habitat temperatures encountered by the organism, namely 4–12°. 4. The two variants of pyruvate kinase do not appear to be isoenzymes in the conventional sense. Electrophoretic and electrofocus analyses revealed only single peaks of activity. 5. The results suggest that the ‘warm’ pyruvate kinase and the ‘cold’ pyruvate kinase are formed by a temperature-dependent interconversion of one protein species. This interconversion has major adaptive significance: as the temperature is lowered the ‘warm’ enzyme is converted into the ‘cold’ enzyme; the opposite situation obtains when the temperature is raised. Temperature changes thus mimic the effects noted for fructose 1,6-diphosphate on certain mammalian pyruvate kinases.

scholarly journals Thermal Stability of Glucokinases inThermoanaerobacter tengcongensis

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Zhong Qian ◽  
Jingjing Zhao ◽  
Xue Bai ◽  
Wei Tong ◽  
Zhen Chen ◽  
...  
Keyword(s):  
Enzyme Assays ◽  
Kinetic Properties ◽  
Heat Shock Protein 60 ◽  
Culture Temperature ◽  
Temperature Dependent ◽  
Temperature Changes ◽  
Thermoanaerobacter Tengcongensis ◽  
Different Temperatures ◽  
Thermal Stability Of ◽  
Optimal Ph

In the genome ofThermoanaerobacter tengcongensis, three genes belonging to ROK (Repressor, ORF, and Kinase) family are annotated as glucokinases (GLKs). Using enzyme assays, the three GLKs were identified as ATP-dependent GLK (ATP-GLK), ADP-dependent GLK (ADP-GLK), and N-acetyl-glucosamine/mannosamine kinase (glu/man-NacK). The kinetic properties of the three GLKs such asKm,Vmax, optimal pH, and temperature were characterized, demonstrating that these enzymes performed the specific functions against varied substrates and under different temperatures. The abundance of ATP-GLK was attenuated when culture temperature was elevated and was almost undetectable at 80°C, whereas the ADP-GLK abundance was insensitive to temperature changes. Using degradation assays, ATP-GLK was found to have significantly faster degradation than ADP-GLK at 80°C. Co-immunoprecipitation results revealed that heat shock protein 60 (HSP60) could interact with ATP-GLK and ADP-GLK at 60 and 75°C, whereas at 80°C, the interaction was only effectively with ADP-GLK but not ATP-GLK. The functions of GLKs inT. tengcongensisare temperature dependent, likely regulated through interactions with HSP60.

Chromatographic Isolation of the LDH-Isoenzymes of Human Blood Platelets and an Investigation of Their Enzyme Kinetics

1968 ◽  
Vol 20 (03/04) ◽  
pp. 301-313 ◽  
Author(s):  
W Schneider ◽  
K Schumacher ◽  
B Thiede ◽  
R Gross
Keyword(s):  
Human Blood ◽  
Blood Platelets ◽  
Deae Cellulose ◽  
Order Reaction ◽  
Kinetic Properties ◽  
Ldh Isoenzymes ◽  
Kinetic Investigations ◽  
Substrate Concentrations ◽  
Chromatographic Isolation ◽  
Human Blood Platelets

SummaryThe LDH-isoenzymes of human blood platelets show a distinct predominance of the isoenzymes 2 and 3 upon chromatography on DEAE-cellulose. Small amounts of LDH-1 are also present, while only traces of LDH-4 and -5 can be detected.Enzyme kinetic investigations of the principal isoenzymes LDH-1, -2 and -3 clearly show that the differences in inhibition constants with pyruvate as substrate which are demonstrable at 25° largely disappear at 37°. On the other hand, the differences among the isoenzymes in their affinity for pyruvate and lactate as substrate as well as in with respect to the optimal substrate concentrations of pyruvate are more marked at 37° than at 25°. Also, the type of inhibition found with lactate as substrate is increasingly the expression of a higher order reaction in going from LDH-1 to LDH-3. A dependence of the LDH distribution pattern upon the metabolism of the cell is discussed. A comparison of our results with thrombocytes with those of other workers with erythrocytes and leucocytes makes it unlikely that the LDH pattern is directly dependent upon the existence of an oxidative metabolism. Rather, the redox potential of the cell could be of importance for the nature of the pattern of isoenzymes and for their differing kinetic properties.

Pyruvate kinase from the liver and kidney of Arapaima gigas

1978 ◽  
Vol 56 (4) ◽  
pp. 852-859 ◽  
Author(s):  
H. Guderley ◽  
J. H. A. Fields ◽  
J. M. Cardenas ◽  
P. W. Hochachka
Keyword(s):  
Pyruvate Kinase ◽  
Arapaima Gigas ◽  
Liver And Kidney ◽  
Low Levels ◽  
Pyruvate Kinases ◽  
Regulatory Properties ◽  
Partial Reversal

Pyruvate kinases from the kidney and liver of the osteoglossid Arapaima gigas were partially purified and characterized kinetically. The two enzymes have different elect rophoretic mobilities at pH 7.0, and while they share some qualitative similarities they show quantitative differences in their catalytic and regulatory properties. Both enzymes are activated by fructose 1.6-bisphosphate and inhibited by low levels of alanine and MgATP. The liver isozyme shows hyperbolic phosphoenolpyruvate binding, with a K1 for alanine inhibition of 0.7 mM and a K1 for MgATP inhibition of 1.0 mM. In contrast, the kidney isozyme shows cooperative phosphoenolpyruvate binding, which is accentuated at low levels of ADP. MgATP inhibition does not increase the cooperativity and shows an apparent K1 of 1.68 mM. The inhibition of alanine leads to considerable increases in the cooperativity and is effective at 1 mM and lower levels. Fructose 1.6-bisphosphate completely reverses the inhibition by alanine for both isozymes, while only leading to a partial reversal of the MgATP inhibition. These regulatory properties of both the kidney and the liver isozymes suit them for function in tissues which undergo both glycolysis and gluconeogenesis.

Temperature-Dependent Photoluminescence Spectra of PbSe Quantum Dots for Temperature Markers

2012 ◽  
Vol 482-484 ◽  
pp. 2547-2550
Author(s):  
Peng Fei Gu ◽  
Ya Nan Wang ◽  
Jia Jia Cao ◽  
Yu Yan ◽  
Tie Qiang Zhang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Temperature Sensitivity ◽  
Peak Position ◽  
Strong Temperature Dependence ◽  
Photoluminescence Spectra ◽  
Temperature Dependent ◽  
Temperature Variations ◽  
Temperature Changes ◽  
Optical Readout ◽  
Temperature Dependent Photoluminescence

We here report the temperature effect on photoluminescence(PL) spectra of PbSe quantum dots (QDs), which exhibit a strong temperature dependence on their spectra position and intensity. They potentially act as the temperature marker, sensing temperature variations and reporting temperature changes remotely through optical readout. In addition, the temperature sensitivity characterized by peak position of PbSe QDs was found to be 0.39nm/°C in a range of 10-100 °C.

Kinetic properties of the muscular pyruvate kinase from the giant marine barnacle, Austromegabalanus psittacus (Molina, 1782) (Cirripedia, Balanomorpha)

Crustaceana ◽  
2005 ◽  
Vol 78 (10) ◽  
pp. 1203-1218
Author(s):  
Daniel López ◽  
Robert Simpfendörfer ◽  
Karin Oelckers ◽  
David Nash
Keyword(s):  
Pyruvate Kinase ◽  
Kinetic Properties

scholarly journals Pyruvate kinases have an intrinsic and conserved decarboxylase activity

2014 ◽  
Vol 458 (2) ◽  
pp. 301-311 ◽  
Author(s):  
Wenhe Zhong ◽  
Hugh P. Morgan ◽  
Matthew W. Nowicki ◽  
Iain W. McNae ◽  
Meng Yuan ◽  
...  
Keyword(s):  
Pyruvate Kinase ◽  
Dicarboxylic Acids ◽  
Enzyme Mechanism ◽  
Decarboxylase Activity ◽  
Solution Studies ◽  
Pyruvate Kinases

We provide an enzyme mechanism for the decarboxylase activity of pyruvate kinase which is conserved from protozoa to mammals. Structural and solution studies of range of related dicarboxylic acids suggest the decarboxylase activity is restricted to oxaloacetate as a substrate.

scholarly journals Emission Characteristics of Fluorescent Labels with Respect to Temperature Changes and Subsequent Effects on DNA Microchip Studies

2005 ◽  
Vol 71 (10) ◽  
pp. 6453-6457 ◽  
Author(s):  
Wen-Tso Liu ◽  
Jer-Horng Wu ◽  
Emily Sze-Ying Li ◽  
Ezrein Shah Selamat
Keyword(s):  
Melting Curve ◽  
Melting Curve Analysis ◽  
Emission Characteristics ◽  
Fluorescent Labels ◽  
Temperature Dependent ◽  
Temperature Changes ◽  
Formamide Concentration ◽  
Effects Of Temperature ◽  
Microarray Studies ◽  
Texas Red

ABSTRACT The effects of temperature, salt concentration, and formamide concentration on the emission characteristics of commonly used fluorescent labels were evaluated on DNA microchips. The emission intensities of different fluorophores without hybridization were observed to vary, each to a different extent, to mainly temperature changes. Rhodamine red, TAMRA (tetramethylrhodamine), and dyes from the carbocyanide group exhibited the largest variations, and Texas Red and Oregon Green exhibited the smallest variations. This temperature dependency was shown to affect results obtained during melting curve analysis in DNA microarray studies. To minimize the bias associated with the temperature-dependent emission of different fluorescent labels, a normalization step was proposed.

The Temperature-Dependent Ideal Shear Strength of Solid Single Crystals

2018 ◽  
Vol 85 (3) ◽  
Author(s):  
Tianbao Cheng ◽  
Daining Fang ◽  
Yazheng Yang
Keyword(s):  
Shear Strength ◽  
Theoretical Model ◽  
Melting Point ◽  
Single Crystals ◽  
Elevated Temperatures ◽  
Absolute Zero ◽  
Temperature Dependent ◽  
Temperature Changes ◽  
First Time ◽  
The Ideal

Knowledge of the ideal shear strength of solid single crystals is of fundamental importance. However, it is very hard to determine this quantity at finite temperatures. In this work, a theoretical model for the temperature-dependent ideal shear strength of solid single crystals is established in the view of energy. To test the drawn model, the ideal shear properties of Al, Cu, and Ni single crystals are calculated and compared with that existing in the literature. The study shows that the ideal shear strength first remains approximately constant and then decreases almost linearly as temperature changes from absolute zero to melting point. As an example of application, the “brittleness parameter” of solids at elevated temperatures is quantitatively characterized for the first time.

Effects of anoxia on the extra- and intracellular acid-base status in the land snail helix lucorum (L.): lack of evidence for a relationship between pyruvate kinase down-regulation and acid-base status

1999 ◽  
Vol 202 (12) ◽  
pp. 1667-1675
Author(s):  
B. Michaelidis ◽  
A. Pallidou ◽  
P. Vakouftsi
Keyword(s):  
Pyruvate Kinase ◽  
Active Form ◽  
Land Snail ◽  
Land Snails ◽  
Kinetic Properties ◽  
Acid Base ◽  
Down Regulation ◽  
Helix Lucorum ◽  
End Products ◽  
Acid Base Status

The aims of the present study were to describe a possible correlation between the regulation of the key glycolytic enzyme pyruvate kinase and the acid-base status in the haemolymph and in several other tissues of land snails during anoxia. To illustrate whether such a relationship exists, we determined (i) the acid-base variables in the haemolymph and tissues of the land snail Helix lucorum, (ii) the kinetic properties of pyruvate kinase from several tissues and (iii) the levels of the anaerobic end-products d-lactate and succinate in the haemolymph and tissues of aerobic and anoxic Helix lucorum. The results showed that the pH of haemolymph (pHe) decreased significantly over the first 20 h of anoxia and then recovered slowly towards control values. A similar pattern was observed for intracellular pH (pHi), which decreased significantly over the first 16 h of anoxia and slowly returned towards control levels. The reduction and recovery of pHi and pHe seem to reflect the rate of anaerobic metabolism. The main anaerobic end-products, d-lactate and succinate, accumulated rapidly during the initial stages of anoxia and more slowly as anoxia progressed. The decrease in the rate of accumulation of anaerobic end-products during prolonged anoxia was due to the conversion of tissue pyruvate kinase to a less active form. The results demonstrate a correlation between pyruvate kinase down-regulation and the recovery of acid-base status in the haemolymph and the tissues of land snails during anoxia.

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