Amylase saccharifying

Griffiths (2) studied the thermal stability of the naturally occurring enzymes in milk at temperatures between 65 and 80°C, in order to choose an enzymatic index of adequate pasteurization of milk. For the acid phosphatase, the D-values of 7.38 min at 75°C and 7.87 min at 80°C corresponded to a z-value of 6.6°C for the inactivation of lactoperoxidase, D-values of 0.80 min at 75°C and 0.075 min at 80°C corresponded to a z-value of 5.4°C for amylase (saccharifying activity), D-values of 0.85 min at 75°C and 0.45 min at 80°C corresponded to a z-value of 16.2°C. The naturally occurring enzymes in milk showed lower D-values than those found for GFPuv in the three buffers. However, a z-value of 16.64°C characterized for GFPuv in phosphate buffer solutions at pH 7.0 was similar to that obtained for amylase in milk. 

Though the data are not included in Table I, concurrent tests were also made of the action of all the a-amylases on crystalline a-maltose (106) and /3-maltose. The unique saccharifying a-amylase of B. subtilis var. amylosacchariticus showed a-D-glucosyl transferring activity with both maltose anomers, confirming the conclusion of Japanese authors (88, 89, 90, 91). The remaining a-amylases showed no detectable action on either maltose anomer under these conditions. 

Since malt is used as a source of liquefying and saccharifying enzymes in whiskey and grain spirits fermentations, and gibberellic acid increases the a- and /3-amylase content of malt, it became desirable to determine gibberellin residues in a distiller s feed by-product. 

Today, most ethanol is made from corn starch. After separation from com by wet milling, starch slurry is thinned with alpha-amylase and saccharified with amyloglu-cosidase. The resulting sugar solution is fermented by Sacchammyces yeast. Modem US ethanol plants use simultaneous scarification, yeast propagation and fermentation. The major portion of fuel-grade ethanol is now produced by continuous fermentation,... 

Molasses, fruit juice, corns, bagasse, Jerusalem artichockes, cassava, whey, sulfite liquor, saw dust and other wood by-products are used as substrates for alcohol and glycerin production. Starch-based substrates should be first saccharified by amylases prepared from barley, fungi or bacteria. Cellulosic materials must also be chemically or enzymatically hydrolyzed before being used as substrates for alcohol production. Clostridium species contain amylases and are able to convert starch and cellulose directly16). 

Starch is first liquefied and hydrolyzed to specific dextrose equivalents with hydrochloric acid. After evaporation to 60 percent solids, a saccharifying enzyme (fungal a-amylase) is added to continue hydrolysis to the desired level. By choosing two or more types of enzymes (such as a-amylase, -amylase, glu-coamylase, pullulanase) and adjusting the initial acid hydrolysis, syrups with different ratios of dextrose, maltose, and higher saccharides can be obtained.92... 

It can be shown, as will be discussed in detail later, that hexasaccharides with maltose linkages are completely converted to maltose by all amylases, and that if a hexasaccharide of this type is transformed into a mixture of saccharides with 1 to 6 units by acid hydrolysis, this mixture is completely saccharified. Thus when a chain of D-glucose units contains only maltose linkages, it is completely broken down by the amylases irrespective of the chain length, and the velocity is for most amylases much the same as in the case of starch. 

If potato starch contains about 20% amylose and if the amylose is saccharified to 100%, it is clear that amylopectin is saccharified by /3-amylase to about 50%. This is confirmed in experiments with amyl-... 

In the literature there has been a certain disagreement as to whether amylose is saccharified completely by /3-amylase. The experiments are complicated by the fact that amylose solutions have a tendency to deposit amylose (retrograde) in which state it is not attacked by the enzyme. But if a sufficient amount of enzyme is used the amylose is, without... 

When starch, amylopectin or glycogen is saccharified by /S-amylase and the maltose is removed, there remains the limit dextrin, called /3-amylase dextrin, Grenzdextrin, a-amylodextrin or in publications from the author s laboratory, simply -dextrin. It gives viscous solutions and is colored blue or violet by iodine. After precipitation with alcohol... 

As mentioned above, /3-amylase does not produce D-glucose. If starch is treated with a mixture of a- and /3-amylase, the yield of D-glucose is much lower than with a-amylase alone. This means that the a-amylase produces D-glucose also from parts of the starch molecules that can be saccharified by the /3-amylase. 

The a-dextrin fractions, PDV to PDXIV, are completely saccharified also by salivary amylase. The salivary amylase produces more maltose from the anomalous fractions of the a-dextrins than does 8-amylase. The reason is, as pointed out above, that these fractions are not completely dextrinized. If we assume for example, that an a-dextrin of molecular weight 3400 contains two branching points (Fig. 5) only the part A-B is... 

If the a-dextrins are treated for a long time with a-amylase they are saccharified more or less completely. This saccharification corresponds to the second slow action of the enzyme on starch. In contradistinction... 

When a /3-dextrin is broken up by the a-amylase into a-dextrins, the a-dextrins, in contradistinction to the /3-dextrin itself, are attacked by the /3-amylase with the liberation of fermentable sugar (Table XlII). This means that when maltose linkages in the interior chains of the /3-dextrin are broken by the a-amylase, anomalous a-dextrins are formed, the normal end chains of which are saccharified by the 8-enzyme (see Fig. 5, page 276). 

The normal a-dextrins are completely saccharified by both enzymes to give maltose and small amounts of D-glucose. From a-dex-trins with an uneven number of D-glucose units the /3-amylase yields... 

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