Sucrose, estimation hydrolysis

Estimation of Catalytic Activity. The catalytic activities of the copolymers on the hydrolysis of polysaccharides were estimated, with the measurement of increase in reducing sugar in the reaction mixture with reaction time according to Somogyi method (22). The hydrolysis rates of sucrose were determined from the measurement of optical rotatory power... 

Sucrose is a nonreducing sugar. It can be estimated by acid hydrolysis followed by determination of glucose and/or fructose. It may also be determined in a like manner and with greater specificity following the action of the enzyme saccharase. The methods employed for fructose can be used for sucrose. Raybin s reagent is specific for sucrose, but it is not very sensitive (R2). 

As long ago as 1913, Leonor Michaelis, director of the biochemical laboratory of the Berlin Municipal Hospital, and Maud Leonora Menten, a young Canadian pathologist in Europe for further training, had published their analysis of the reaction between sucrose and invertase, the enzyme that catalyzes hydrolysis of sucrose. Michaelis and Menten dissolved sucrose in acetate buffer and, holding the solution at 25 C, measured its optical activity. At zero time they added the enzyme and observed the change in optical activity until the reaction was complete. Michaelis and Menten extrapolated the data to zero time in order to estimate the initial velocity of the reaction, and they repeated the experiments with three different concentrations of substrate and three of enzyme. 

In its present stage of development, the biochemical method probably leaves much to be desired, but additional study should make it a valuable tool for the analysis of the complex mixtures occurring in plant extracts. Methods (86) for the estimation of raflSnose in the presence of sucrose have been described which depend on selective enzymic hydrolysis. 

Example 16.2 Estimate the equilibrium constant for the hydrolysis of sucrose to make invert sugar, an equimolar mixture of glucose and fmctose. 

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