Sola M M, Salto R, Oliver F J, Gutiérrez M, Vargas A M
Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Granada, Spain.
J Biol Chem. 1993 Sep 15;268(26):19352-7.
Gluconeogenic flux exceeds glycolytic flux at the hexose-phosphate steps when measured in extracts of kidney cortex from well-fed rats. Addition of AMP and/or fructose 2,6-bisphosphate to the assay medium partially eradicates the difference. Using principles developed by Kacser, H., and Burns, J. A. ((1973) in Rate Control of Biological Processes (Davies, D. D., ed) pp. 65-104, Cambridge University Press, London) and Heinrich R., and Rapoport T. A. ((1974) Eur. J. Biochem. 42, 97-105), flux control coefficients of enzymes participating in the pathway segments from glucose 6-phosphate to triose-phosphates and from glycerol 3-phosphate to glucose 6-phosphate were determined by additions of the respective enzyme to the system. Results show that the flux control coefficients are highly modulated by the presence of allosteric effectors, as might be expected according to the regulatory properties of phosphofructokinase and fructose-1,6-bisphosphatase purified from this origin. Measured reductions of fructose 2,6-bisphosphate and AMP levels during acidosis, starvation, or after phenylephrine treatment suggest that these changes contribute to enhanced gluconeogenesis under these conditions.
在测定饱食大鼠肾皮质提取物时，在磷酸己糖步骤中糖异生通量超过糖酵解通量。向测定培养基中添加AMP和/或果糖2,6-二磷酸可部分消除这种差异。利用Kacser, H.和Burns, J. A.（（1973年）《生物过程的速率控制》（Davies, D. D.编）第65 - 104页，剑桥大学出版社，伦敦）以及Heinrich R.和Rapoport T. A.（（1974年）《欧洲生物化学杂志》42卷，97 - 105页）提出的原理，通过向系统中添加相应酶来确定参与从葡萄糖6-磷酸到磷酸丙糖以及从3-磷酸甘油到葡萄糖6-磷酸的途径段的酶的通量控制系数。结果表明，通量控制系数受到变构效应剂的高度调节，这与从该来源纯化的磷酸果糖激酶和果糖-1,6-二磷酸酶的调节特性所预期的情况一致。在酸中毒、饥饿或去氧肾上腺素治疗后测得的果糖2,6-二磷酸和AMP水平的降低表明，这些变化有助于在这些条件下增强糖异生作用。
