Invertases

Sucrose on hydrolysis with dilute acids, or with the enzyme invertase (or ju-crase p. 514,) gives rise to one molecule of glucose and one molecule of fructose ... 

Invertase (sucrasc) small intestine, yeast sucrose glucose and fructose 6 2 (gut) 4 8 (yeast)... 

Yeast contains a number of enzymes, more particularly inyertase and zymase. Invertase catalyses the hydrolysis of sucrose to glucose and fructose (cf. the catalysis of this reaction by acids, p. 369). 

Sucrose is dextro-rotatory. Fructose shows a laevo-rotation greater in magnitude than the dextro-rotation shown by glucose. Hence as the hydrolysis of sucrose proceeds, the dextro-rotation gradually falls to zero and the solution finally shows a laevo-rotation. This hydrolysis is therefore sometimes called inversion and so the enzyme which catalyses the reaction is known as " invertase. Its more systematic name is, however, sucrase. 

A) 20 ml. of sugar solution and 2 ml. of the invertase solution obtained above. 

Mix each solution well and place the boiling- tubes in a water-bath maintained at 50 . After 10 minutes, transfer i ml. of each of the reaction mixtures to separate test-tubes, add 2 ml. of Fehling s solution to each and boil. A marked reduction is obtained in A, no reduction is obtained in B, and no reduction or only very slight reduction is obtained in C. This shows that the activity of the invertase is destroyed both by heat and alkali. 

Actually the optimum pH for the invertase reaction is about 4-8, and under these conditions the reaction proceeds even more rapidly. The solution can be adjusted approximately to this pH by adding 6 ml. of 1% acetic acid at the beginning of the experiment. 

Liquid sucrose and Hquid invert, generally made by redissolving white sugar and inverting with invertase enzyme, are refinery products in Europe and outside the United States. In the United States they have been almost completely replaced by cheaper com symps made by enzymatic hydrolysis of starch and isomerization of glucose. 

Enzymes. Invertase (P-fmctofuranosidase) is commercially produced from S. cerevisiae or S. uvarum. The enzyme, a glycoproteia, is not excreted but transported to the cell wall. It is, therefore, isolated by subjecting the cells to autolysis followed by filtration and precipitation with either ethanol or isopropanol. The commercial product is available dry or ia the form of a solutioa containing 50% glycerol as a stabilizer. The maia uses are ia sucrose hydrolysis ia high-test molasses and ia the productioa of cream-ceatered candies. 

By the end of the nineteenth century a more descriptive system was in use. The suffix -ase was appended to the name of the substrate involved in the reaction, eg, amylase, ceUulase, protease, Hpase, urease, etc. Names that reflected the function of the enzyme with the suffix -ase were also used, eg, invertase, transferase, isomerase, oxidase. 

At a partieular room temperature, results for the hydrolysis of suerose, S, eatalyzed hy the enzyme invertase (Cg = 1 x 10 mol in a hateh reaetor are given hy ... 

Competitive inhibition is important in biological control mechanisms for instance, if the product assumes the role of an inhibitor. The enzyme invertase catalyzes the hydrolysis of sucrose into glucose and fructose. As glucose is a competitive inhibitor, it ensures that the reaction does not proceed too far. 

Cell wall properties of transgenic tobacco plants that express a yeast derived acid invertase in their vacuole... 

In the present study we used transgenic plants to analyse the amount of control exerted by an additional vacuolar invertase on the allocation of carbohydrates to the plant cell wall. Since physical parameters indicated a significant modification in the thermodynamic state of these invertase plants, the monosaccharide composition, the pore size and the amount of free and bound acids present in the cell wall were measured. 

Cell expansion rate, turgor, osmotic pressure, and water potential of leaf 6 and leaf 11 of wild type and invertase plants... 

Size exclusion limits measured in 3 leaves of wild type and invertase plants. 

To characterize modifications in the cell wall composition of transgenic invertase plants we determined the distribution of neutral saccharides (Fig. 1). Obviously, the relative amounts of fucose and mannose were slightly reduced in leaf 6 of transgenic plants, whereas arabinose was increased. The other saccharides remained unchanged. 

The size exclusion limit of cell wall fragments is a measure of the density of the pectin network. When wild type and invertase plants were compared no significant differences in the pore size emerged (Table 2). 

We thank Petra Lembke and Petra Heese for assistance during the cell wall analysis. We thank Dr. U. Sonnewald for the generous gift of the transgenic invertase plants. This work was supported by a DFG grant to SHB (HO 1605/1-2). 

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