Hydrolysis maltose

Levitt, M., C. Fine, J. Furne, and D. Levitt. Use of maltose hydrolysis measurements to characterize the interaction between the aqueous diffusion barrier and the epithelium in the rat jejunum., /. Clin. Invest. 1996, 97, 2308-2315... 

The heat evolution on maltose fermentation can be approximated by multiplying the figure for glucose by two and adding the further 15.9 kj/mole required for maltose hydrolysis (Eq. 16.9). Fermentation temperatures of 15-18°C are desirable for beer production. 

For the assay of maltitol, Renneberg (1988) coupled the competitive inhibition by maltitol of the glucoamylase-catalyzed maltose hydrolysis with the GOD-mediated indication of the liberated glucose. 

Adjacent to the mucosa, no agitation is possible and the transport rate of most drugs is determined by passive diffusion in the aqueous medium. The thickness of the layer in situ amounts to about 500 pm and in vitro to about 150-200 pm. The average unstirred layer thickness can be calculated from Michaelis-Menten constant and maximal velocity of maltose hydrolysis by intestinal maltase. In... 

Enzymatic hydrolysis of polysaccharides (cellulose, starch) or oligosaccharides (maltose, saccharose, lactose) for the synthesis of food products is another class of processes MBR have been applied to. Paolucci-Jeanjean et al [4.56] have recently reported, for example, the production of low molecular weight hydrolysates from the reaction of cassava starch over a-amylase. In this case the UF membrane separates the enzyme and substrate from the reaction products for recycle. Good productivity without noticeable enzyme losses was obtained. Houng et al [4.57] had similar good success with maltose hydrolysis using the same type of MBR,... 

The evolutions in maltose and glucose concentrations were not in accordance with the amount of panose synthesised, pointing again towards maltose hydrolysis in addition to maltose transglucosylation. 

Table 1.4. Conditions for the reversal of maltose hydrolysis catalysed by an extract of yeast cells...

Figure 1,2. Reversal of maltose hydrolysis catalysed by an extract of dried yeast. The extract, prepared as described in the text, was mixed with solutions of glucose and maltose as described in Table 1.4. At various times (see dates) the amounts of maltose and glucose were estimated from the reducing power and the optical rotation of the solutions. For each experiment (see Table 1.4) the results are plotted as the percentage of the total carbohydrate present as glucose and maltose. (From Hill, 1898 reproduced with the kind permission of the Royal Society of Chemistry from the original paper, (Fig. 5, p. 652).)...

Maltase and a-glucosidases in general catalyze transfer reactions in the same manner as galactosidases. It was shown many years ago that maltose hydrolysis could be reversed, although the structure of the product was not established conclusively. Experiments with maltose and labeled glucose have shown the incorporation of the isotope into maltose during incubation with an enzyme preparation from intestinal mucosa.i ... 

Lactose on hydrolysis gives glucose and an isomeric monosaccharide galactose, which may be given the symbol Ga-r. The lactose molecule may be represented as Ga-r-G-r, and it has therefore also a free potential aldehyde group and is a reducing sugar like maltose. 

Carbohydrates may be divided into monosaccharides, disaccharides and polysaccharides. The monosaccharides under certain conditions react as polyhydroxy-aldehydes or polyhydroxy-ketones two important representatives are glucose CjHjjO (an aldose) and fructose (laevulose) CgHuO, (a ketose). Upon hydrolysis di- and polysaccharides 3deld ultimately monosaccharides. Common disaccharides are sucrose, lactose and maltose (all of molecular formula C,2H2. 0,), whilst starch, dextrin and cellulose, (CjHjoOj), in which n > 4, are typical polysaccharides. 

Disaccharides, e.g., lactose, which yield galactose upon hydrolysis, will also give the sparingly-soluble mucic acid but in poorer 3deld. This reaction may be employed for the differentiation between certain disaccharides lactose — mucic + saccharic acids sucrose — saccharic acid only maltose — saccharic acid only. 

Maltose obtained by the hydrolysis of starch and cellobiose by the hydrolysis of cellulose are isomenc disaccharides In both maltose and cellobiose two d glucopyra nose units are joined by a glycosidic bond between C 1 of one unit and C 4 of the other The two are diastereomers differing only m the stereochemistry at the anomeric carbon of the glycoside bond maltose is an a glycoside cellobiose is a (3 glycoside... 

Amylase occurs in many plants, such as barley, wheat, rye, soy beans, and potatoes, where it is generally accompanied by some a-amylase. [ -Amylase initiates hydrolysis at the nonreducing end of an amylose or amylopectin chain, and removes maltose units successively until the reducing end of the molecule is encountered in amylose or a branch is met in amylopectin. ( -Amylase is used commercially in the preparation of maltose symps. After P-amylase hydrolysis of amylopectin there remains a P-amylase limit dextrin. ( -Amylase has been used as a probe of the fine stmcture of amylopectin (43-46). 

The glycosidic bond to an anomeric carbon can be either a or (3. Maltose, the disaccharide obtained by enzyme-catalyzed hydrolysis of starch, consists of two cv-D-glucopyranose units joined by a 1->4-o-glycoside bond. Cellobiose, the disaccharide obtained by partial hydrolysis of cellulose, consists of two /3-o-glucopyranose units joined by a 1—>4-/3-glycoside bond. 

Many enzymes are extremely specific. For example, the enzyme maltase catalyzes the hydrolysis of maltose ... 

Using bond energies, estimate AH for the hydrolysis of maltose to... 

Hehre and coworkers showed that beta amylase from sweet potatoes, an inverting, a-specific exo-(l 4)-glucanase, catalyzes the hydrolysis of jS-maltosyl fluoride with complex kinetics which indicated the participation of two substrate molecules in the release of fluoride ion. Furthermore, the reaction was strongly accelerated by the addition of methyl ) -maltoside. Hydrolysis of a-maltosyl fluoride, on the other hand, obeyed Michaelis-Menten kinetics. The main product with both a- and yj-maltosyl fluoride was )S-maltose. The results with )3-maltosyl fluoride were interpreted by the assumption of a glycosylation reaction preceding hydrolysis by which a malto-tetraoside is formed by the replacement of fluoride ion by a second substrate molecule or added methyl -maltoside (see Scheme 5). 

The physiologically important disaccharides are maltose, sucrose, and lactose (Table 13-4 Figure 13-11). Hydrolysis of sucrose yields a mixture of glucose and... 

Maltose Digestion by amylase or hydrolysis of starch. Germinating cereals and malt. ... 

The hydrolysis of starch by salivary and pancreatic amylases catalyze random hydrolysis of a(l—>4) glycoside bonds, yielding dextrins, then a mixmre of glucose, maltose, and isomaltose (from the branch points in amylopectin). 

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