© 1977 Oxford University Press
RESEARCH-ARTICLE |
Some General Characteristics of Glycolysis in vitro and its Inhibition by High Concentrations of Chloride Salts
Agronomy Department, University of Western Australia Nedlands, W.A. 6009, Western Australia
Glycolysis in vitro was studied, using extracts from germinating pea seeds.
Steady state rates of CO2 evolution declined long before all substrate, either glucose or sugar phosphate, was converted to CO2 and ethanol. High rates of CO2 evolution were restored by addition of more substrate.
Some factors which regulate glycolysis in vitro were investigated, using glucose as a substrate. High levels of P1 and Mg2+ were required to obtain optimum rates of CO2 evolution. Levels of intermediates indicated that high P1 acted via a stimulation of 6-phosphofructokinase.
Glucose, in the presence of hexokinase, induced substantially higher rates of CO2 evolution than a number of sugar phosphates. However, evolution of CO2, from glucose-6-phosphate or fructose-6-phosphate, was greatly stimulated by the addition of purified yeast pyruvate decarboxylase, rates sometimes exceeding those attained when glucose was used as a substrate. The reason for this stimulation by pyruvate decarboxylase is unknown.
Effects of high KCl and NaCl were measured, using glucose as a substrate. KCl and NaCl, at 200 mM and higher concentrations, reduced steady state rates of glycolysis. The degree of inhibition was much greater at high than at low rates of glycolysis. This was shown, for example, when using different concentrations of P1.
High levels of KCl and NaCl greatly increased levels of fructose-1,6-diphosphate and triose phosphates, particularly at low P1, and did not reduce the ‘net carbon movement past 6-phosphofructokinase’ Thus high KCl and NaCl weakened the control of glycolysis by 6-phos-phofructokinase.