Invertase from yeast

The specificity of levansucrase98 is dependent not only on the d-fructoside but also on the aldoside residue of the substrate. Neither inulin nor methyl D-fructofuranoside was hydrolyzed by levansucrase, and even when these two substrates were hydrolyzed by inulase (prepared from inulin-fermenting Torula yeast) or by yeast invertase respectively, no levan formation occurred with levansucrase. However, neither methyl D-fructofuranoside nor inulin inhibited levan formation from sucrose by levansucrase. No levan was formed from potassium D-glucose... 

Indirect evidence of the reversal of enzymic synthesis of levan has recently been obtained.10Ba Enzyme preparations from B. subtilis were shown to contain an enzyme capable of hydrolyzing levan (in addition to the levan-synthesizing enzyme) in a system composed of D-glucose, levan, yeast invertase (to hydrolyze sucrose formed) and the B. subtilis enzyme preparation. 

The introduction of the invertase from yeast alone was not sufficient. Invertase cleaves sucrose to release the two component sugars, glucose and fructose. While fructose can be readily metabolized by fructokinase in potato tubers, there is insufficient hexokinase activity in developing potato tubers to bring the glucose into intermediary metabolism. Therefore, it was necessary to introduce a second transgene, a bacterial glucokinase, in order to ensure that the hexoses became available for subsequent metabolism.25... 

Thus when o-glucose was added to a solution containing levan, yeast invertase and an enzyme preparation from Bacillus subtUis, it was found that the decomposition of the levan became accelerated, presumably through the synthesis and decomposition of sucrose47 as follows ... 

Thiosucrose (98) was also a good inhibitor for the two enzymes which act on sucrose, the levansucrase from Bacillus subtilis and the yeast invertase [19]. 

Cetylpyridinium chloride (CPC)/ hexane a-Amylase from brewers yeast and invertase from bakers yeast Enzyme activities in cells entrapped in RMs were high compared to free cells [284]... 

A relatively more active source of melibiase is crude invertase from brewers yeast. Yeast melibiase is nearly free from /J-D-galactosidase, but it contains /3-D-mannosidase as well as /3-D-fructofuranosidase.23... 

Planteose is an exception to the general behavior of the raffinose oligosaccharides in that it is stable against the action of yeast invertase.22 29 This property, shared also by melezitose,45 is explained by the lack of an unsubstituted /3-D-fructofuranoside group. The resistance to invertase action can be utilized in the preparative separation of planteose from sucrose.29... 

G21. Gross, D., Paper electrophoresis of the oligosaccharides synthesized from sucrose by yeast invertase. Nature 173, 487 (1954). 

Commercial yeast invertase (Bioinvert ) was immobilized by adsorption on anion-exchange resins, collectively named Dowex (1x8 50-400,1x4 50-400, and 1x2 100-400). Optimal binding was obtained at pH 5.5 and 32°C. Among different polystyrene beads, the complex Dowex-1x4-200/invertase showed a yield coupling and an immobilization coefficient equal to 100%. The thermodynamic and kinetic parameters for sucrose hydrolysis for both soluble and insoluble enzyme were evaluated. The complex Dowex/inver-tase was stable without any desorption of enzyme from the support during the reaction, and it had thermodynamic parameters equal to the soluble form. The stability against pH presented by the soluble invertase was between 4.0 and 5.0, whereas for insoluble enzyme it was between 5.0 and 6.0. In both cases, the optimal pH values were found in the range of the stability interval. The Km and Vmax for the immobilized invertase were 38.2 mM and 0.0489 U/mL, and for the soluble enzyme were 40.3 mM and 0.0320 U/mL. 

The commercial yeast invertase (Bioinvert ) was purchased from Quest International . Styrene-divinylbenzene bead derivatives having different granulometry (50-400 mesh) and different degrees of crosslinking (2-8%) were purchased from Sigma (St. Louis, MO). All other chemicals were of analytical grade. 

The polysaccharides associated with yeast invertase do not give a precipitate with Fehling solution, leading to the erroneous conclusion that mannan is absent. However, precipitation is inhibited by proteins, and mannan can be isolated after removal of protein. The proportions of O-methylmannose fragments obtained from the mannan in a methylation study were virtually the same as those obtained from methylated bakers yeast mannan (see Table III, p. 388). 

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