Sucrose reaction with invertase

Sucrose a-D-glucose + p-D-fructose a,p(1 2) Sugar beet, sugar cane, sorghum and carrot roots. Fermentable. Hydrolysed by dilute acids or enzyme invertase (sucrase) to one molecule of glucose and one molecule of fructose. Relatively stable to reaction with alkali... 

Many of the early studies were conducted with enzymes from fermentation, particularly invertase, which catalyzes the hydrolysis of sucrose to monosaccharides D-glucose and D-fmctose. With the introduction of the concept of hydrogen ion concentration, expressed by the logarithmic scale of pH (Sorensen, 1909), Michaelis and Menten (1913) realized the necessity for carrying out definitive experiments with invertase. They controlled the pH of the reaction medium by using acetate buffer, allowed for the mutarotation of the product and measured initial reaction rates at different substrate concentrations. Michaelis and Menten described their experiments by a simple kinetic law which afforded a foundation for a subsequent rapid development of numerous kinetic models for enzyme-catalyzed reactions. Although the contribution of previous workers, especially Henri (1902, 1903), was substantial, Michaelis and Menten are regarded as the founders of modern enzyme kinetics due to the definitive nature of their experiments and the viability of their kinetic theory. 

The decomposition of the compound of sucrose and invertase must be a monomolecular reaction, and therefore the velocity of hydrolysis must be proportional to the concentration of sucrose with invertase. 

In the development of the kinetic equations it was assumed that the concentration of the solvent (water) remains constant throughout the reaction. At high substrate concentrations this is not true, however, and there is a deviation from the theoretical equations. In the case of the inversion of sucrose by yeast invertase, the effect of the sucrose and water concentration was investigated by Nelson and Schubert (11), who found that the velocity of hydrolysis increases with substrate concentration to about 6 % sucrose but thereafter decreases steadily. As shown by these investigators, however, the decrease may be accounted for by the decrease in the water concentration as the sugar concentration increases. 

Fructosans have been examined in detail (11,13,28,77,131,165,212) and their structures are in agreement with the theory that they are built up from sucrose by enz3Hnic transfructosidation (92,77). Trisaccharides, occurring along with other oligosaccharides, have been separated and characterized from reactions of invertase on sucrose (5,251) and also from extracts of tubers of Jerusalem artichoke (18,77). Seasonal changes in the carbohydrate composition of these tubers have been described (19,77). 

Applications of chemical kinetics to enzyme-catalyzed reactions soon followed. Because of the ease with which its progress could be monitored polarimetrically, enzyme hydrolysis of sucrose by invertase was a popular system for study. O Sullivan and Tompson (1890) concluded that the reaction obeyed the Law of Mass Action and in a paper entitled, Invertase A Contribution to the History of an Enzyme or Unorganized Ferment , they wrote [Enzymes] possess a life function without life. Is there anything [in their actions] which can be distinguished from ordinary chemical action ... 

Bioethanol can be produced from a large variety of carbohydrates with a general formula of (CHjO) . Chemical reaction is composed of enzymatic hydrolysis of sucrose followed by fermentation of simple sugars. Fermentation of sucrose is performed using commercial yeast such as Saccharomyces cerevisiae. First, invertase enzyme in the yeast catalyzes the hydrolysis of sucrose to convert it into glucose and fmctose. 

The most efficient method for the clean hydrolysis of sucrose is by the use of invertase, leading to an equimolar mixture of glucose and fructose (invert sugar). The presence of salts increases the rate of thermal degradation of sucrose.337 The reaction is also possible in the presence of such heterogeneous acidic catalysts as zeolites.338 The hydrolysis of the glycosidic bond is the first step of a number of subsequent reactions that can occur on the glucose and fructose residues, such as dehydrations, combinations with amino acids (Maillard reaction), and many other chemicals or fermentation processes.339... 

A veiy important aspect of chemical kinetics is that dealing with the rates of enzyme-catalyzed reactions. Enzymes are a class of proteins that catalyze virtually all biochemical reactions. In this experiment we shall study the inversion of sucrose, as catalyzed by the enzyme invertase (/3-fractofuranidase) derived from yeast. The rate of the enzyme-catalyzed reaction will then be compared to that of the same reaction catalyzed by hydrogen ions. 

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