harmaline , which is positively charged in the physiological range of ph , might in fact compete , not directly with the substrate site , but rather with an allosterically-related sodium-binding site which has been postulated to be involved in the activation of sucrase by the alkali-metal ions ( mahmood and alvarado , arch . biochem . biophys . 168 , 585 , 1975 ) .
C0037473
sodium
C0025554
alkali-metal