Regulation of Pyruvate Kinase from the Hepatopancreas of the Crab Carcinus maenas

1975 ◽  
Vol 3 (3) ◽  
pp. 400-402 ◽  
Author(s):  
IAN G. GILES ◽  
PETER C. POAT ◽  
KENNETH A. MUNDAY
Keyword(s):  
Pyruvate Kinase ◽  
Carcinus Maenas

Substrate Inhibition of Pyruvate Kinase Isolated from the Leg Muscle of Carcinus maenas

1976 ◽  
Vol 4 (6) ◽  
pp. 1158-1160 ◽  
Author(s):  
COLIN J. NEWTON ◽  
PETER C. POAT ◽  
KENNETH A. MUNDAY
Keyword(s):  
Pyruvate Kinase ◽  
Substrate Inhibition ◽  
Carcinus Maenas ◽  
Leg Muscle

scholarly journals An investigation of the interactions of the allosteric modifiers of pyruvate kinase with the enzyme from Carcinus maenas hepatopancreas

1977 ◽  
Vol 165 (1) ◽  
pp. 97-105 ◽  
Author(s):  
I G Giles ◽  
P C Poat ◽  
K A Munday
Keyword(s):  
Enzyme Activity ◽  
Pyruvate Kinase ◽  
Enzyme Preparation ◽  
Carcinus Maenas ◽  
Maximal Activity ◽  
Initial Increase ◽  
Low Concentration ◽  
Saturation Kinetics ◽  
Fructose 1,6 Bisphosphate ◽  
Allosteric Activator

1. Pyruvate kinase purified from the hepatopancrease of Carcinus maenas exhibited sigmoidal saturation kinetics with respect to the substrate phosphoenolpyruvate in the absence of the allosteric activator fructose 1,6-bisphosphate, but normal hyperbolic saturation was seen in the presence of this activator. The activation appears to be the result of a decrease in the s0.5 (phosphoenolpyruvate) and not to a change in Vmax. 2. In the presence of ADP and ATP at a constant nucleotide-pool size the results indicate that phosphoenolpyruvate co-operativity is lost on increasing the [ATP]/[ADP] ratio. 3. Paralleling this change is the observation that the fructose 1,6-bisphosphate activation became less at the [ATP]/[ATP] ratio was increased. This was due to the enzyme exhibiting a near-maximal activity in the absence of activator. 4. L-Alanine inhibited the enzyme, but homotropic co-operative interactions were only seen with a cruder (1000000g supernatant) enzyme preparation. The inhibition by alanine could be overcome by increasing the concentration of either phosphoenolpyruvate or fructose 1,6-bisphosphate, although increasing the L-alanine concentration did not appear to be able to reverse the activation by fructose 1,6-bisphosphate. 5. In the presence of a low concentration of phosphoenolpyruvate, increasing the concentration of the product, ATP, caused an initial increase in enzyme activity, followed by an inhibitory phase. In the presence of either fructose 1,6-bisphosphate or L-alanine only inhibition was seen. 6. The inhibition by ATP could not be completely reversed by fructose 1,6-bisphosphate.

A Kinetic Study of Muscle Pyruvate Kinase from Carcinus maenas

1976 ◽  
Vol 4 (3) ◽  
pp. 479-481 ◽  
Author(s):  
COLIN J. NEWTON ◽  
PETER C. POAT ◽  
KENNETH A. MUNDAY
Keyword(s):  
Kinetic Study ◽  
Pyruvate Kinase ◽  
Carcinus Maenas ◽  
Muscle Pyruvate Kinase

scholarly journals Purification and properties of pyruvate kinase from the hepatopancreas of Carcinus maenas

1976 ◽  
Vol 153 (1) ◽  
pp. 127-134 ◽  
Author(s):  
I G Giles ◽  
P C Poat ◽  
K A Munday
Keyword(s):  
Pyruvate Kinase ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Carcinus Maenas ◽  
Deae Cellulose ◽  
Protein Band ◽  
Polyacrylamide Gel ◽  
Major Protein ◽  
Major Protein Band

Pyruvatekinase from the hepatopancreas of the common shore crab, Carcinus maenas, was purified to a specific activity of 240 units/mg of protein in the assay conditions described. 2. In one method of purification the enzymic activity could be resolved into two fractions after chromatography on DEAE-cellulose. Fructose 1, 6-diphosphate was able to effect the conversion of one form (peak 1) into the second (peak 2). 3. In the presence of a saturating concentration of fructose 1, 6-diphosphate both forms of the enzyme were kinetically similar. 4. Polyacrylamide-gel electrophoresis of the enzyme 1 day after preparation showed a single protein band. On storage at least three protein bands became visible, all of which were associated with pyruvate kinase activity. 5. Chromatography of the enzyme on Sephadex G-200 indicated a mol.wt. of 247000, but in the presence of fructose 1, 6-diphosphate the elution volume of the enzyme increased corresponding to a mol.wt. of 193000. 6 Dissociation of the enzyme in sodium dodecyl sulphate and 2-mercaptoethanol followed by polyacrylamide-gel electrophoresis produced one major protein band with a mol.wt. of 55000.

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