Improvement of Characteristics of Maltase from Marrow (Cucurbita pepo L.) Cotyledons by its Immobilization on Chitin

Maltase is one of the key enzymes in our digestive processes, as it is the main salivary enzyme in the digestion of carbohydrates in the mouth. The present investigation aimed to evaluate the impact of some additive materials on maltase activity, and the role of immobilization of the enzyme on chitin in improving its characters. After different purification steps, the recorded specific activity of maltase from Cucurbita pepo L. was 385 units mg^-1 protein and the fold was 4.4. Addition of EDTA, 0.5% (w/v) bovine serum albumin (BSA), 10 mM nicotinic acid, 20 to 30 mM PEG, glycine, proline, and alanine stimulated the maltase activity. On the other hand, 0.5 % (V/V) of Triton–X100, Tween-80, 10 mM diphenylamine, and 5% (v/v) 2-mercaptoethanol inhibited maltase activity. Also, maltase activity was inhibited by succinic anhydride > sodium fluoride >phethalic anhydride in the order as arranged. After 5 days of storage at 25 ℃, the enzyme retained 43.5% of its activity. After immobilization on chitin, the enzyme retained 162.4 U from 240 U of its activity after 6 cycles of reusability. Also, the pH and temperature of optimum activity were shifted from 6.0 and 50 ℃ in case of free maltase to 9.0 and 60 ᴼC in case of immobilized maltase respectively. Also, K⁺, Mn²⁺, Mg²⁺, Co²⁺, and Zn²⁺ activated immobilized maltase with a higher rate compared with the free maltase. On the other hand, Hg²⁺ and Cu²⁺ inhibited the immobilized maltase activity at a lower rate than free maltase. Moreover, immobilized maltase expressed higher response to activation with sorbitol and mannitol than free maltase‎‎.