Gluconolactone, inhibition

The reaction mixture contained in a final volume of 0.1 mL, 0.1 M sodium phosphate buffer (pH 6.8), 1.0 mM tryptamine, 5 mM secologanin, and 3 mM dithiothreitol. To inhibit glucosidase activity, 100 mM D(+)-gluconic acid-5-D-gluconolactone was included. The incubation was started by addition of 10 /xL of enzyme. After 30 minutes of incubation at 30°C, the reaction was stopped by addition of 0.1 mL of 5% trichloroacetic acid. Before centrifugation, 25 /xL of 8 mM codeine hydrochloride was added as the internal standard. HPLC analysis was performed on 4 /xL aliquots. With enzyme purified to a specific activity of 710 pkat per milligram of protein, the reaction was linear with time for 1 hour and with protein up to at least 50 /xg of protein during a 20-minute incubation period. 

Figure 3. Estimation of exo-fi-l 4-glucanase from inhibition by gluconolactone. R Lactone/substrate = 0.1 (wt.)...

Stachybotrys atra (235). An intracellular enzyme from this fungus, which released glucose as the sole product from / -l,4-oligoglucosides up to CL 11 and was not inhibited by 1,5-gluconolactone (236), is apparently an exo-hydrolase. The / -l,4-glucosyl linkage in p-nitrophenyl-a-cellobioside was also hydrolyzed. 

Although the pig epididymaJ amidase was earlier reported to be inhibited by 2-acetamido-2-deoxy-l,5-D-gluconolactone (Clamp al., 1966), it appears that this enzyme and those from rat liver or epididymis are remarkedly unaffected by this pow erful inhibitor of eio- A -acetyl-D-hexosaminidase (Conchie et al., 1969). 

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