Abstract
1. The mechanism of rabbit muscle pyruvate kinase was investigated by measurements of fluxes, isotope trapping, steady-state velocity and binding of the substrates. All measurements were made at pH8.5 in Tris/HCl buffer and at 5mm-free Mg2+. 2. Methods of preparing [32P]phosphoenolpyruvate from [32P]Pi in high yield and determining [32P]-phosphoenolpyruvate and [8-14C]ADP are described. 3. The ratio Flux of ATP to ADP/Flux of ATP to phosphoenolpyruvate (measured at equilibrium) increased hyperbolically with ADP concentration from unity to about 2.1 at 2mm-ADP, but was unaffected by phosphoenolpyruvate concentration. Since the ratio is greater than unity, one pathway for the addition of substrates must involve phosphoenolpyruvate adding first to the enzyme in a rate-limiting step. However, the substrates must also add in the alternative order, because of the non-linear increase in the ratio with ADP concentration and because the rate of increase is very much less than that predicted from the steady-state velocity data for an ordered addition. The lack of influence of phosphoenolpyruvate on the ratio is consistent with the rapid addition of ADP in the alternative pathway. At low ADP concentrations the alternative pathway contributes less than 33% to the total reaction. 4. Isotope trapping was observed with [32P]phosphoenolpyruvate, confirming that when phosphoenolpyruvate adds first to the enzyme it is in a rate-limiting step. The release of phosphoenolpyruvate from the ternary complex must also be a slow step. Trapping was not observed with [8-14C]ADP, hence the addition of ADP to the free enzyme must be rapid unless its dissociation constant is very large (>20mm). 5. Binding studies showed that 4mol of [32P]phosphoenolpyruvate binds to 1mol of the enzyme, probably unligated to Mg2+, with a dissociation constant appropriate to the mechanism indicated above. Binding of [8-14C]ADP could not be detected, and hence the binding of ADP occurs by a low-affinity step. The latter is also demanded by the steady-state velocity data. 6. The ratio Flux of phosphoenolpyruvate to ATP/Flux of phosphoenolpyruvate to pyruvate (determined from the incorporation of label into phosphoenolpyruvate from [3-14C]-pyruvate or [γ-32P]ATP during the forward reaction) did not differ significantly from unity. Steady-state velocity data predicted grossly different flux ratios for ordered dissociations of the products, and the results indicate that the dissociation must be rapid and random. The data also exclude a Ping-Pong mechanism. 7. Permissible rate constants for the above mechanism are calculated. The results indicate a high degree of cooperativity in binding, whatever the order of addition of substrate.
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Selected References
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- Ainsworth S., MacFarlane N. A kinetic study of rabbit muscle pyruvate kinase. Biochem J. 1973 Feb;131(2):223–236. doi: 10.1042/bj1310223. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Britton H. G., Clarke J. B. The mechanism of the phosphoglucomutase reaction. Studies on rabbit muscle phosphoglucomutase with flux techniques. Biochem J. 1968 Nov;110(2):161–180. doi: 10.1042/bj1100161. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Britton H. G., Dann L. G. Use of flux ratio measurements for the determination of the order of addition of substrates and products in enzyme reactions. Biochem J. 1978 Jan 1;169(1):29–37. doi: 10.1042/bj1690029. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Britton H. G., Dann L. G. Use of flux ratio measurements for the determination of the order of addition of substrates and products in enzyme reactions. Biochem J. 1978 Jan 1;169(1):29–37. doi: 10.1042/bj1690029. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Britton H. G., Dann L. G. Use of flux ratio measurements for the determination of the order of addition of substrates and products in enzyme reactions. Biochem J. 1978 Jan 1;169(1):29–37. doi: 10.1042/bj1690029. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Britton H. G., Dann L. G. Use of flux ratio measurements for the determination of the order of addition of substrates and products in enzyme reactions. Biochem J. 1978 Jan 1;169(1):29–37. doi: 10.1042/bj1690029. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Britton H. G. The concept and use of flux measurements in enzyme studies. A theoretical analysis. Arch Biochem Biophys. 1966 Oct;117(1):167–183. doi: 10.1016/0003-9861(66)90140-8. [DOI] [PubMed] [Google Scholar]
- Britton H. G. The concept and use of flux measurements in enzyme studies. A theoretical analysis. Arch Biochem Biophys. 1966 Oct;117(1):167–183. doi: 10.1016/0003-9861(66)90140-8. [DOI] [PubMed] [Google Scholar]
- Colowick S. P., Womack F. C. Binding of diffusible molecules by macromolecules: rapid measurement by rate of dialysis. J Biol Chem. 1969 Feb 25;244(4):774–777. [PubMed] [Google Scholar]
- Cottam G. L., Hollenberg P. F., Coon M. J. Subunit structure of rabbit muscle pyruvate kinase. J Biol Chem. 1969 Mar 25;244(6):1481–1486. [PubMed] [Google Scholar]
- Dann L. G., Britton H. G. Mechanism of "L"-type pyruvate kinase from rabbit liver. Evidence against phosphoenzyme formation. Biochem J. 1977 Feb 1;161(2):445–448. doi: 10.1042/bj1610445. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dann L. G., Britton H. G. The reaction of diethyl pyrocarbonate with pyruvate kinase. Biochem J. 1974 Feb;137(2):405–407. doi: 10.1042/bj1370405. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dyson R. D., Cardenas J. M., Barsotti R. J. The reversibility of skeletal muscle pyruvate kinase and an assessment of its capacity to support glyconeogenesis. J Biol Chem. 1975 May 10;250(9):3316–3321. [PubMed] [Google Scholar]
- EGGLESTON L. V., HEMS R. Separation of adenosine phosphates by paper chromotography and the equilibrium constant of the myokinase system. Biochem J. 1952 Sep;52(1):156–160. doi: 10.1042/bj0520156. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Garland P. B., Newsholme E. A., Randle P. J. Regulation of glucose uptake by muscle. 9. Effects of fatty acids and ketone bodies, and of alloxan-diabetes and starvation, on pyruvate metabolism and on lactate-pyruvate and L-glycerol 3-phosphate-dihydroxyacetone phosphate concentration ratios in rat heart and rat diaphragm muscles. Biochem J. 1964 Dec;93(3):665–678. doi: 10.1042/bj0930665. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Giles I. G., Poat P. C., Munday K. A. The kinetics of rabbit muscle pyruvate kinase. Initial-velocity, substrate- and product-inhibition and isotopic-exchange studies of the reverse reaction. Biochem J. 1976 Sep 1;157(3):577–589. doi: 10.1042/bj1570577. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Irving M. G., Williams J. F. Kinetic studies on the regulation of rabbit liver pyruvate kinase. Biochem J. 1973 Feb;131(2):287–301. doi: 10.1042/bj1310287. [DOI] [PMC free article] [PubMed] [Google Scholar]
- James T. L., Reuben J., Cohn M. Nuclear magnetic resonance study of the binding of phosphoenolpyruvate and phosphoenol-alpha-ketobutyrate to manganese pyruvate kinase. Temperature, frequency,and monovalent cation dependence of water proton nuclear magnetic resonance relaxation rates. J Biol Chem. 1973 Sep 25;248(18):6443–6449. [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- Liao C. L., Atkinson D. E. Regulation at the phosphoenolpyruvate branchpoint in Azotobacter vinelandii: pyruvate kinase. J Bacteriol. 1971 Apr;106(1):37–44. doi: 10.1128/jb.106.1.37-44.1971. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Llorente P., Marco R., Sols A. Regulation of liver pyruvate kinase and the phosphoenolpyruvate crossroads. Eur J Biochem. 1970 Mar 1;13(1):45–54. doi: 10.1111/j.1432-1033.1970.tb00897.x. [DOI] [PubMed] [Google Scholar]
- Macfarlane N., Ainsworth S. A kinetic study of Baker's-yeast pyruvate kinase activated by fructose 1,6-diphosphate. Biochem J. 1972 Oct;129(5):1035–1047. doi: 10.1042/bj1291035. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Macfarlane N., Ainsworth S. A kinetic study of pig liver pyruvate kinase activated by fructose diphosphate. Biochem J. 1974 Jun;139(3):499–508. doi: 10.1042/bj1390499. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Melchior J. B. The role of metal ions in the pyruvic kinase reaction. Biochemistry. 1965 Aug;4(8):1518–1525. doi: 10.1021/bi00884a009. [DOI] [PubMed] [Google Scholar]
- Mildvan A. S., Cohn M. Kinetic and magnetic resonance studies of the pyruvate kinase reaction. II. Complexes of enzyme, metal, and substrates. J Biol Chem. 1966 Mar 10;241(5):1178–1193. [PubMed] [Google Scholar]
- Nicholas P. C., Bachelard H. S. Kinetic properties of cerebral pyruvate kinase. Biochem J. 1974 Jul;141(1):165–171. doi: 10.1042/bj1410165. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Phillips R. C., George P., Rutman R. J. Thermodynamic studies of the formation and ionization of the magnesium(II) complexes of ADP and ATP over the pH range 5 to 9. J Am Chem Soc. 1966 Jun 20;88(12):2631–2640. doi: 10.1021/ja00964a002. [DOI] [PubMed] [Google Scholar]
- REYNARD A. M., HASS L. F., JACOBSEN D. D., BOYER P. D. The correlation of reaction kinetics and substrate binding with the mechanism of pyruvate kinase. J Biol Chem. 1961 Aug;236:2277–2283. [PubMed] [Google Scholar]
- Robinson J. L., Rose I. A. The proton transfer reactions of muscle pyruvate kinase. J Biol Chem. 1972 Feb 25;247(4):1096–1105. [PubMed] [Google Scholar]
- Rose I. A., O'Connell E. L., Litwin S. Determination of the rate of hexokinase-glucose dissociation by the isotope-trapping method. J Biol Chem. 1974 Aug 25;249(16):5163–5168. [PubMed] [Google Scholar]
- SUGINO Y., MIYOSHI Y. THE SPECIFIC PRECIPITATION OF ORTHOPHOSPHATE AND SOME BIOCHEMICAL APPLICATIONS. J Biol Chem. 1964 Jul;239:2360–2364. [PubMed] [Google Scholar]
- Schendel P. F., Wells R. D. The synthesis and purification of (gamma-32P)-adenosine triphosphate with high specific activity. J Biol Chem. 1973 Dec 10;248(23):8319–8321. [PubMed] [Google Scholar]
- TIETZ A., OCHOA S. Fluorokinase and pyruvic kinase. Arch Biochem Biophys. 1958 Dec;78(2):477–493. doi: 10.1016/0003-9861(58)90372-2. [DOI] [PubMed] [Google Scholar]
- WILKINSON G. N. Statistical estimations in enzyme kinetics. Biochem J. 1961 Aug;80:324–332. doi: 10.1042/bj0800324. [DOI] [PMC free article] [PubMed] [Google Scholar]
- WOLD F., BALLOU C. E. Studies on the enzyme enolase. I. Equilibrium studies. J Biol Chem. 1957 Jul;227(1):301–312. [PubMed] [Google Scholar]
