Effects of seasonal change and prolonged anoxia on metabolic enzymes of Littorina littorea

2001 ◽  
Vol 79 (5) ◽  
pp. 907-915 ◽  
Author(s):  
Steven C Greenway ◽  
Kenneth B Storey
Keyword(s):  
Pyruvate Kinase ◽  
Digestive Gland ◽  
Seasonal Change ◽  
Littorina Littorea ◽  
Kinetic Properties ◽  
Enzyme Kinetic ◽  
Seasonal Differences ◽  
Exposure In Vivo ◽  
Induced Changes

The effects of seasonal change (July versus November) and prolonged anoxia (N2 atmosphere at 5 or 10°C for 6 days) exposure in vivo on the activities of 18 enzymes, as well as the kinetic properties of phosphofructokinase (PFK) and pyruvate kinase (PK), were investigated in foot muscle and digestive gland of the marine periwinkle Littorina littorea L. Seasonal differences in enzyme maximal activities were tissue-specific, with generally increased activities during the summer and changes in a greater number of enzymes in digestive gland than in foot muscle. Seasonal differences in the kinetic properties of PFK and PK were observed in both tissues. PK from digestive gland of winter animals showed a much higher S0.5 for phosphoenolpyruvate and stronger changes in enzyme kinetic properties in response to anoxia than did the enzyme in summer animals; this may suggest the presence of seasonal isozymes. The effects of anoxia were tissue- and season-specific. Anoxia exposure during the winter induced a greater number of changes in enzyme maximal activities in foot muscle than in digestive gland. Anoxia-induced changes in the kinetic properties of both PFK and PK were also seen in both organs. For PK, these changes were consistent with less active enzyme forms in the anoxic state. Hence, both seasonal and environmental (anoxia) factors influence enzyme maximal activities and kinetic properties in L. littorea.

Postnatal regulation of canine oxygen delivery: control of erythrocyte 2,3-DPG levels

1982 ◽  
Vol 242 (4) ◽  
pp. H500-H506
Author(s):  
P. A. Mueggler ◽  
J. A. Black
Keyword(s):  
Pyruvate Kinase ◽  
Oxygen Affinity ◽  
Kinetic Properties ◽  
Intracellular Activity ◽  
Slow Decline ◽  
Blood Oxygen Affinity ◽  
Intracellular Concentrations ◽  
Glycolytic Rate ◽  
2,3 Dpg

The oxygen affinity of canine blood changes markedly following birth. These changes are correlated with alterations in the intracellular concentration of 2,3-diphosphoglycerate (2,3-DPG). We have examined the control of erythrocyte glycolysis by measurements of intracellular enzymes and intermediates, and we have identified the component responsible for regulation of 2,3-DPG concentration and hence blood oxygen affinity during canine postnatal development. The concentration of 2,3-DPG could be regulated entirely by the enzymes of the Rapoport-Luebering shunt. We have not detected any alterations in the levels or intracellular activity of 2,3-DPG mutase or 2,3-DPG phosphatase during development; therefore postnatal changes of 2,3-DPG must be a result of changes in the intracellular concentrations of 1,3-diphosphoglycerate (1,3-DPG) that are controlled by other reactions in the glycolytic pathway. Neither low intracellular concentrations of glucose, the glycolytic substrate, nor an inherently low glycolytic rate can account for the low 2,3-DPG levels at birth. 1,3-DPG concentrations and hence 2,3-DPG concentrations are controlled by the activity of pyruvate kinase, which acts as a glycolytic sink reaction. The intracellular activity of pyruvate kinase decreases during the first 50-60 days of age and causes the accumulation of 2,3-DPG. There is a subsequent change in the in vivo kinetic properties of the enzyme, giving increased intracellular activity and resulting in the slow decline of 2,3-DPG concentrations toward normal adult values.

scholarly journals Influence of Hormones, Second Messengers and pH on the Expression of Metabolic Responses to Anoxia in a Marine Whelk

1989 ◽  
Vol 145 (1) ◽  
pp. 31-43 ◽  
Author(s):  
STEPHEN P. J. BROOKS ◽  
KENNETH B. STOREY
Keyword(s):  
Pyruvate Kinase ◽  
Second Messengers ◽  
Metabolic Responses ◽  
Kinetic Properties ◽  
Ionophore A23187 ◽  
Ph Change ◽  
Tissue Ph ◽  
Biochemical Responses

The roles of hormones, second messengers and pH in triggering or potentiating biochemical responses to anaerobiosis were evaluated using in vitro incubations of isolated muscle tissues (foot, radular retractor, ventricle) from the marine whelk Busycon canaliculatum (L.). Incubating tissues in vitro under anoxic conditions stimulated changes in muscle fmctose-2,6-bisphosphate levels and pyruvate kinase kinetics (Km values for phosphoenolpyruvate, I50 values for L-alanine) that were virtually equivalent to those that occur in vivo. Additions of hormones (epinephrine, norepinephrine, octopamine, serotonin, glucagon, insulin) or inhibitors of prostaglandin synthesis (dexamethasone, aspirin) had no effect on these metabolic responses to anoxia. The second messenger compounds, dibutyryl cyclic AMP and Ca2+ + ionophore A23187 + phorbol myristate acetate, produced isolated and tissue-specific responses in muscles incubated under aerobic conditions, but the magnitude and pattern of these responses differed from those seen in anoxia. Second messengers also had no effect on the development of biochemical responses in anoxic muscles. Tissue pH was artificially altered in order to evaluate the role of pH change (acidification occurs during anoxia in vivo) in the control of metabolic responses to anoxia. In all cases, the changes in the kinetic properties of pyruvate kinase (PK) correlated with the state of oxygenation of the tissue and not with the measured tissue pH value; higher tissue pH did not prevent anoxiainduced phosphorylation of PK and lower tissue pH did not alter the kinetic patterns of the aerobic enzyme. Overall, the study indicates that cells and tissues of the whelk respond individually to anoxia and that coordination of the action of protein kinases during anoxia is not mediated by pH or by common secondmessenger mechanisms.

Oligomeric Forms Of Pyruvate Kinase From Chlorella With Different Kinetic Properties

1991 ◽  
Vol 46 (5-6) ◽  
pp. 416-422 ◽  
Author(s):  
G. Ruyters ◽  
N. Grotjohann ◽  
W. Kowallik
Keyword(s):  
Pyruvate Kinase ◽  
Total Activity ◽  
Substrate Affinity ◽  
Kinetic Properties ◽  
Resting Cells ◽  
Carbohydrate Degradation ◽  
Enzyme Species ◽  
Oligomeric Forms

Fast protein liquid chromatography on Superose 6 of crude extracts from the chlorophyllfree mutant no. 20 of the unicellular green alga Chlorella kessleri reveals two possibly oligomeric forms of pyruvate kinase (2.7.1.40). Their occurrence is markedly altered in the course of heterotrophic growth with changing levels of exogenous glucose as carbon source with only one enzyme species with a MW of 400 kDa existing in growing cells, two forms of 400 and 580 kDa in resting cells. Substrate affinity towards PEP of the 400 kDa form is better than that of the 580 kDa species; responses to the effector AMP are different as well. In vitro, addition of PEP or of AMP leads to the formation of higher MW enzyme species with MW of 730, 1050 and 1400 kDA without affecting the total activity. In vivo alterations in the levels of several metabolites including PEP upon addition of glucose have been shown to occur. Therefore, it is discussed, whether changes in the concentration of intermediates and effectors may provide the mechanism for the increased rate of carbohydrate degradation by affecting the occurrence and/or ratio of the various PK forms with different kinetic and regulatory properties. Upon blue light irradiation, which also stimulates carbohydrate breakdown of the Chlorella mutant cells, the distribution of PK is shifted towards the species with higher substrate affinity, a result being in accordance with the above conception

scholarly journals Exposure in vivo Induced Changes in Neural Circuitry for Pain-Related Fear: A Longitudinal fMRI Study in Chronic Low Back Pain

2019 ◽  
Vol 13 ◽  
Author(s):  
Inge Timmers ◽  
Jeroen R. de Jong ◽  
Mariëlle Goossens ◽  
Jeanine A. Verbunt ◽  
Rob J. Smeets ◽  
...  
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Chronic Low Back Pain ◽  
Neural Circuitry ◽  
Low Back ◽  
Fmri Study ◽  
Exposure In Vivo ◽  
Induced Changes

120-LB: Small Molecule Activator of Pyruvate Kinase Regulates In Vivo Glucose Homeostasis

Diabetes ◽  
2020 ◽  
Vol 69 (Supplement 1) ◽  
pp. 120-LB
Author(s):  
ABUDUKADIER ABULIZI ◽  
REBECCA L. CARDONE ◽  
STEPHAN SIEBEL ◽  
CHARLES KUNG ◽  
RICHARD KIBBEY
Keyword(s):  
Pyruvate Kinase ◽  
Small Molecule ◽  
Glucose Homeostasis
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