Amylases activation energies

Another approach of energy transfer-based probe has been demonstrated for a-Amylase sensing/98 In this case amylose was doubly labeled, by fluorescein derivative (donor) and Procion Red MX8B (acceptor). As a-Amylase catalyzes the cleavage of the amylose into smaller units, the average distance between fluorescein and Procion Red increases, which reduces the degree of quenching. The rate of increase in fluorescence intensity is proportional to ee-amylase activity. 

The activation energies of several alpha-amylases have been determined, and are shown in Table V. 

The effect of temperature on the kinetics of alpha-amylase action has been studied, and, from the variation of reaction velocity, activation energies have been determined for several enzymes, as shown in Table V. The variation of with temperature has also been studied, and, from such measurements, the heat of formation of the enzyme—substrate complex has been calculated to be —3.4 Kcal. per mole for sorghum alpha-amylase and —7 Kcal. per mole for hog-... 

TG typically shows three mass-loss steps water loss (room temperature to 150 C), thermal decomposition of the carbohydrates - starch, amylase, amyl pectin (250-400 °C) and secondary thermal decomposition of carbohydrates of low molecular mass and fibres (400-600 °C). Com and its derivatives (hominy, gritz, vitamilho (pre-cooked flour) and bran) were characterized and their kinetics of decomposition evaluated. Once activation energies and preexponential factors were provided, these could be correlated with properties of the food materials and used for quality control purposes. 

For starch hydrolysis by microbial a-amylase, the following activation energies, which lie between the limits stated in section 2.5.4.2, were derived from e. g. the Arrhenius diagram (Fig. 2.35) ... 

Fig. 2.35. Fungal a-amylase. Amylose hydrolysis versus temperature. Arrhenius diagram for assessing the activation energy of enzyme catalysis and enzyme inactivation V = total reaction rate...

Carbohydrates, or starches, which are complex polysaccharides, are hydrolyzed to oligosaccharides and disaccharides by the action of pancreatic amylase. Disaccharides, including lactase, sucrase, and maltase, are enzymatically split by enzymes contained in the microvilli of enterocytes. Glucose and other monosaccharides are absorbed by an active transport mechanism and this action is coupled to energy derived from a sodium pump mechanism. 

Microbial fermentation of CSM, which was proposed to detoxify FG in the CSM (Zhang et ah, 2006a,b), seems promising because some exoenzymes such as cellulolytic enzymes, amylase, protease, and lipolytic enzymes that are secreted by certain microorganisms, and some vitamins, as well as some unknown active substances are produced in the fermented CSM (Brock et ah, 1994), which adds nutritional value of the fermented CSM. Recently, Qian et ah (2008) reported that in situ alkaline-catalyzed transesterification could produce a CSM with FG and TG contents below the FAO standard. However, the requirement for a high amount of methanol usage in the in situ transesterification and the potential energy consumption to remove the methanol in the meal may be an obstacle for its practical application. 

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