Inhibition of brush border sucrase by indoline 2,3-dione (isatin) in rat small intestine.
Isatin (15-25 mM) inhibited rat brush border sucrase by 40% in presence of Na+ and the inhibition was enhanced to over 60% in sodium free medium. Sucrase inhibition by isatin was dependent on pH. Kinetic analysis revealed a pure capacity type (Vmax-effect) inhibition of sucrase activity by isatin in presence of sodium. But it changed to affinity type (K-effect) in sodium free medium. The value of Ki was around 20-25 mM under these conditions. Enzyme inhibition by isatin was alleviated by increasing Na+ or sucrose concentrations. Other monovalent cations like K+, Li+ and Cs+ were also effective in restoring the enzyme activity to control levels. The effectiveness of the metal ions in alleviating the enzyme inhibition was in the order of Na+ > Cs+ > K+ > Li+.
Mousavi
M L
ML
Department of Biochemistry, Panjab University, Chandigarh, India.
Bansal
R C
RC
Singh
K
K
Mahmood
A
A
D000818:Animals; D007421:Intestine, Small / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D007510:Isatin / Q000494:pharmacology*; D008297:Male; D008871:Microvilli / Q000187:drug effects / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D013393:Sucrase / Q000037:antagonists & inhibitors*
D007510:Isatin; D013393:Sucrase