Maximum activities and effects of fructose bisphosphate on pyruvate kinase from muscles of vertebrates and invertebrates in relation to the control of glycolysis

Abstract

1. Comparison of the maximum activities of pyruvate kinase with those of phosphofructokinase in a large number of muscles from invertebrates and vertebrates indicates that, in general, in any individual muscle, the activity of pyruvate kinase is only severalfold higher than that of phosphofructokinase. This is consistent with the suggestion, based on massaction ratio data, that the pyruvate kinase reaction is non-equilibrium in muscle. However, the range of activities of pyruvate kinase in these muscles is considerably larger than that of phosphofructokinase.' This difference almost disappears if the enzyme activities from muscles that are known to possess an.anaerobic 'succinate pathway' are excluded. It is suggested that, in these muscles, phosphofructokinase provides glycolytic residues for both pyruvate kinase (i.e. -glycolysis) and phosphoenolpyruvate carboxykinase (i.e. the succinate pathway). This is. supported by a negative correlation between the activity ratio, pyruvate kinase/phosphofructokinase, and the activities of nucleoside diphosphokinase in these muscles, since high.activities of nucleoside diphosphokinase are considered to indicate the presence of the succinate pathway. 2. The effect of fructose bisphosphate on the activities of pyruvate kinase from many different muscles was studied. The stimulatory effect of fructose bisphosphate appears to be lost whenever an efficient system for supply of oxygen to the muscles is developed (e.g. insects, squids, birds and mammals). This suggests that activation of pyruvate kinase is important in the co-ordinated regulation of glycolysis in anaerobic or hypoxic conditions, when the change in glycolytic flux during the transition from rest to activity needs to be large in order to provide sufficient energy for the contractile activity. However, lack of this effect in the anaerobic muscles of the birds and mammals suggests that another metabolic control may exist for avian and mammalian pyruvate kinase in these muscles.

Muscle enzyme activities in a deep‐sea squaloid shark, Centroscyllium fabricii, compared with its shallow‐living relative, Squalus acanthias

“…All enzyme activities were determined spectrophotometrically at 51C 7 0.11C on a Beckman DU640 spectrophotometer equipped with a jacketed cell holder connected to a thermostated water chiller. This temperature was chosen because it is near, or within, the published temperature ranges for both species, 1-4.51C for Alp et al, 1976;Zammit et al, 1978;Moon and Mommsen, 1987;Sidell et al, 1987;Dickson et al, 1993. Deep living teleosts data from Childress and Somero (1979).…”

“…Deep-sea demersal teleosts, n¼8; with duplicate values for 6 species averaged for all enzymes. Data for shallow living elasmobranchs: Alp et al, 1976;Zammit et al, 1978;Sullivan and Somero, 1980;Moon and Mommsen, 1987;Dickson et al, 1993;Battersby et al, 1996. Data for deep-sea demersal teleosts from Sullivan and Somero, 1980;.…”

“…Where necessary, activities adjusted to 51C using a Q 10 of 2. Crabtree and Newsholme, 1972;Alp et al, 1976;Zammit et al, 1978;Moon and Mommsen, 1987;Dickson et al, 1993. Where necessary, activities adjusted to 51C using a Q 10 of 2.…”

Protective effects of vitamin C against biochemical toxicity induced by malathion pesticides in male albino rat

“…Pyruvatekinase (PK) was assayed according to the method of McManus and James (McManus and James, 1975). Glucose phosphate isomerase (GPI) was assayed according to the method of King (King, 1974), phosphofructokinase (PFK) according to the method of Zammit et al (1978), and lactate dehydrogenase (LDH) activity according to the method of Cabaud and Wroblewski (1958). Aspartate and alanine aminotransferases according to the method of Reitman and Frankel (1957).…”

The role of vitamin C in alteration of enzymes responsible of energy metabolism induced by administration of tamoxifen to mouse

“…Pyruvatekinase (PK) according to the method of McManus and James [11]. Glucose phosphate isomerase (GPI) according to the method of King [12], Phosphofructokinase (PFK) according to the method of Zammit et al [13] and Lactate dehydrogenase (LDH) activity according to the method of Cabaud and Wroblewski [14]. Phosphoenolpyruvate carboxykinase (PEPCK) according to the method of Suarez et al [15] and Glucose-6-phos-phatase according to the method of Swanson [16].…”