Amylase enzymatic activity

Fig. 24. Kinetics of add inactivation of a-amylase (Bac. subtilis) in solution (/, 2) and immobilized on Biocarb (3) 1) pH 2 2) and 3) pH 4. A/A0 is the value of relative enzymatic activity (compared to the initial activity A0 before inactivation), substrate — starch...

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-... 

Phosphate and bicarbonate ions are important substrates for many enzymatic processes and as such have regulatory functions. Bicarbonate controls the key enzyme of photosynthesis, ribulose bisphosphate carboxylase, by carbamate formation (Fig. 13-12). Chloride ions activate amylases and may affect the action of "G proteins" that mediate hormone actions. Other observed effects of ions are too numerous to mention. 

Water is added instead of amylase in control experiments. Our enzymatic activity definition is 1 unit of amylase hydrolyses 1.0 mg of starch in 3 min at pH 6.6 at 20°C. 

Crews et al. [81] studied cooked cod by means of a two-step in vitro gastrointestinal enzymolysis. For the first step of sample preparation they employed gastric juice (1 percent m/v pepsin, pH = 2.0, in 0.15 mol l-1 NaCl) at 37°C for 4 h. Afterwards a pancreatin-based mixture was added to the sample solution containing 1.5 percent m/v pancreatin, 0.5 percent m/v amylase, and 0.15 percent m/v bile salts in 0.15 mol l-1 NaCl at pH = 6.9 for a further 4 h at 37°C. The relatively short (8 h) enzymatic activity and the lack of enzymes capable of hydrolyzing proteins directly into amino acids resulted in the identification of inorganic Se (IV) only, as no selenoamino acids could be detected. 

CZE offers the potential of ultramicroanalyses of enzymatic activities in biological samples. This application could be useful in forensic cases when only trace amounts of biological specimens are available—for example, in the detection of amylase activity from saliva extracted from stamps or envelopes. 

Polyphenolic catechins and theaflavins exist as either monomers or polymers in green and black teas, respectively, and are both well known to be inhibitory and bactericidal against Streptococcus spp. They bind to surface proteins of the bacteria, and induce aggregation and inhibit the enzymatic activity of glucosyl transferase. Both teas inhibit salivary and streptococcal amylase, overall, leading to reduction in plaque. Studies in animals have shown that tea consumption reduces caries, and it has been associated with lower caries levels in humans. ... 

The malt, which is rich in colour, is free of amylase it is a good foam builder and is used mainly for the flavouring of malt and bock beers. Light caramel malt is produced through a similar process however, it is dried at a low temperature after starch conversion. It is still enzymatically active, lightly coloured and increases the mouth-feel and foaming properties of beers produced from light malt. 

Enzymes such as salivary a-amylase and lysozyme, as well as bacterial glucosyltransferases immobilised in the pellicle layer, have been shown to maintain their enzymatic activities [13, 50, 53, 54],... 

A new amylase isolated from a Mucor sp. (Mucoraceae) associated with Spirastrella sp., a marine sponge from the Andaman Sea (India), was studied for its enzymatic activity. This enzyme has an optimal pH of 5.0 and an optimal temperature of 60°C. It was strongly inhibited by EDTA [177]. This is the first description of amylasic activity relative to a marine Zygomycotina. 

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