Behavior of manganese ion in basic medium: consequence for the measurement of enzymatic activities using nitrophenyl derivatives

The use of nitrophenyl derivatives in the determination of the influence of manganese ion on catalytic activities of glycosidases and phosphatases remains a problem. In fact, in this study, adding manganese chloride or manganese sulfate to sodium hydroxyde or sodium carbonate in aqueous solution yielded secondary reactions. These secondary reactions affected the absorbance for wavelengths varying between 400-420 nm. This chemical behavior did not allow reliable results in determining the influence of manganese ion on glycosidase and phosphatase activities, when nitrophenyl derivatives were used as substrates. This study showed that this problem could be avoided when natural substrates such as disaccharides (glycosidases) and phosphorylglycosides (phosphatases) were used in enzymatic tests.