Determination of the transient period of the EIS complex and investigation of the suppression of blood glucose levels by L-arabinose in healthy adults.

PURPOSE

L-Arabinose uncompetitively inhibits intestinal sucrase by forming an enzyme-inhibitor-substrate (EIS) complex. The transient period of the EIS complex affects the time span of inhibition. We determined the apparent transient period of the EIS complex of sucrase, L-arabinose, and sucrose both in vitro and in humans.

METHODS

Intestinal acetone powder (a source of sucrase), L-arabinose, and sucrose were mixed and injected into a dialysis membrane that was placed in a sucrose solution. The production rate of D-glucose and the release rate of L-arabinose from sucrase were determined. We also investigated the suppression of blood glucose levels by L-arabinose in 21 healthy volunteers. Sucrose (40 g) was ingested with or without L-arabinose (2 g), then blood glucose values were measured, which returned to steady-state conditions within 2 h. Volunteers were then given 90 g of commercial adzuki bean jelly containing 40 g sucrose as the sucrose load, and blood glucose values were measured again.

RESULTS

Addition of L-arabinose reduced the production rate of D -glucose compared to the rates measured in the absence of L-arabinose for several hours in vitro. L-Arabinose was released at a lower rate in the presence of sucrose than in its absence. Blood glucose values measured 2 h after sucrose was given with L -arabinose were significantly lower than those measured when L-arabinose was not given (Δ change in maximum value: with L-arabinose, 53.8 ± 19.7 mg/dL; without L-arabinose, 65.0 ± 17.7 mg/dL).

CONCLUSION

The EIS complex of sucrase-L -arabinose-sucrose was maintained for several hours both in vitro and in humans.