Inhibition of glycogen synthase I from rabbit skeletal muscles by 1,5-gluconolactone

The effect of 1.5-gluconolactone on the activity of rabbit skeletal muscle glycogen synthase I was investigated. Using statistic methods (pair regressive analysis) and computer analysis on a Robotron EC 1834 personal computer, it was found that 1.5-gluconolactone is a true competitive inhibitor of the enzyme in respect of UDP-glucose. Similar to UDP, 1.5-gluconolactone increases the Km value for UDP-glucose without affecting the V value. The Ki value for 1.5-gluconolactone is equal to 123 + 8 microM and it coincides with the Km value for UDP-glucose.