A-Amylase Activity

In this chapter we describe the use of pea seeds to express the bacterial enzyme a-amylase. Bacterial exoenzymes like the heat stable a-amylase from Bacillus licheni-formis are important for starch hydrolysis in the food industry. The enzymatic properties of a-amylase are well understood [13,14], it is one of the most thermostable enzymes in nature and it is the most commonly used enzyme in biotechnological processes. Although fermentation in bacteria allows highly efficient enzyme production, plant-based synthesis allows in situ enzymatic activity to degrade endogenous reserve starch, as shown in experiments with non-crop plants performed under greenhouse conditions [12,15]. Finally, the quantitative and sensitive detection of a-amylase activ-... 

The expression profile of the USP promoter was monitored under field conditions using a-amylase activity as a reporter. The earliest sign of a-amylase activity was observed 8 DAP. Although the absolute level remained low, a -10-fold increase in promoter activity was detected between 12 and 13 DAP. The activity steadily increased during seed development reaching maximum levels of about 6000 CU kg-1 in mature seeds (Fig. 12.2). 

The Hagberg Falling Number test only just qualifies for this section as it is an effective way of measuring the a-amylase activity of wheat or flour. It has the considerable advantage that it is unaffected by any added fungal a-amylase. In addition, it only requires a supply of distilled water and electricity - there is no need for chemical glassware or any reagents. 

Rye Starch. Rye starch gelatinises at or around the temperature at which a-amylase has its maximum activity (55-70°C). a-Amylase activity tends to be high in rye flour so steps have to be taken to minimise it. One step is to acidify the dough either by adding acid or... 

Several plant defensins have also been found to be inhibitors of various enzymes in plant pests. The plant defensins Slctl, SIo 2, and SIa3 were the first plant defensins where inhibition of a-amylase was shown at low concentration whereas purothionins inhibited a-amylase activity only at high concentrations. Blal and BIa2 isolated from barley are two more representatives of proteinaceous a-amylase inhibitors in the plant defensin family. ... 

Wheat <Dairy products> starch, protein, moisture, ash, hardness, damaged starch, a-amylase activity, amino add, color value, ratio of contaminated bran, bread making quality, discrimination of cultivar... 

Sukul NC, De A, Sukul A, Sinhababu SP. 2002. Potentized Mercuric chloride and Mercuric iodide enhance a-amylase activity in virto. Homeopathy 91 217-220. 

CDTGase displays a-amylase activity. In this case, water is the acceptor and starch or the cyclodextrin is cleaved, resulting in a shorter starch chain or a linear malto-oligosaccharide when a cyclodextrin is the substrate. 

Application and Principle This procedure is used to determine the a-amylase activity of enzyme preparations derived from Aspergillus niger var. Aspergillus oryzae var. Rhizopus oryzae var. and barley malt. The assay is based on the time required to obtain a standard degree of hydrolysis of a starch solution at 30° 0.1°. The degree of hydrolysis is determined by comparing the iodine color of the hydrolysate with that of a standard. 

Amylase Solution Dissolve into 5 mL of water a quantity of (3-amylase, free from a-amylase activity (Sigma Chemical Co., Catalog No. A7005), equivalent to 250 mg of 13-amylase with 2000° diastatic power. 

Apparatus Use the Reference Color Standard, the Comparator, and the Comparator Tubes as described under a-Amylase Activity (Nonbacterial), described in this Appendix, but use either daylight or daylight-type fluorescent lamps as the light source for the Comparator. (Incandescent lamps give slightly lower results.)... 

Dilute Iodine Solution Prepare as directed under a-Amylase Activity (Nonbacterial). 

At zero time, rapidly pipet 10.0 mL of the Sample Preparation into the equilibrated mixture, and continue as directed in the Procedure under a -Amylase Activity (Nonbacterial), beginning with. mix immediately by swirling, stopper the flask.. .. ... 

Calculate the a-amylase activity of the sample, expressed as BAU, by the formula... 

Whitten RO, Chandler WL, Thomas MGE, Clayson KJ, Fine JS. Survey of a-amylase activity and isoamylases in autopsy tissue. Clin Chem 1988 34 1552-5,... 

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