Amylase salivary

Various conditions such as perforated peptic ulcer, cholecystitis, common bile duct and intestinal obstruction, trauma to the abdomen inducing pancreatitis and ruptured ectopic pregnancy may cause an elevated serum amylase but the levels are usually not as high as those found in acute pancreatitis. Mumps and bacterial parotitis, which block the secretion of salivary amylase are associated with mild elevations of serum amylase. 

ZHANG J and KASHKET s (1998) Inhibition of salivary amylase by black and green teas and their effect on the intraoral hydrolysis of starch . Caries Res, 32, 233-8. 

Saliva begins the process of chemical digestion with salivary amylase. This enzyme splits starch molecules into fragments. Specifically, polysaccharides, or starches, are broken down into maltose, a disaccharide consisting of two glucose molecules. Salivary amylase may account for up to 75% of starch digestion before it is denatured by gastric acid in the stomach. 

Suppose we start with a starch-rich meal, say one containing a lot of pasta or bread. The digestion of starches begins in the mouth. Saliva contains an enzyme, salivary amylase (aka ptyalin), which catalyzes the conversion of starch to simple sugars such as glucose. This process is completed in the small intestine under the influence of other enzymes in the amylase class. This completes the first phase of carbohydrate catabolism the conversion of complex, polymeric carbohydrates (e.g., starches) to their simple monomeric units, the sugars. 

Tphe complexing of virtually all purines with aromatic molecules seems - to have far-reaching biological significance. For example, it is known that caffeine affects the rates of many enzymatic reactions (e.g., 0.01, 0.05, and 0.10M caffeine will inhibit salivary amylase 29, 54, and 72% respectively) (12), and purine can decrease the helix-coil transition temperature of the proteins bovine serum albumin and lysozyme (2). It is not unreasonable to expect the involvement of caffeine-aromatic and purine-aromatic complexes because caffeine derivatives and purine complex with the aromatic amino acids tyrosine, phenylalanine, and tryptophan (2). (In fact tryptophan forms a stable 1 to 1 crystalline complex in 0.5M theophylline glycol.)... 

Enzymes are very efficient natural catalysts present in plants and animals. They do not require high temperatures to break down the starch to maltose. In humans, a salivary amylase breaks down the starch in our food. If you chew on a piece of bread for several minutes, you will notice a sweet taste in your mouth. The above hydrolysis reactions are summarised in Figure 15.21. 

The second and third of these steps depend on a supply of appropriate carbohydrate substrates, most favorably sucrose, in the mouth. The latter can become available either directly (sugar ingested in food or drink) or be derived from dietary starch by the action of bacterial or salivary amylases, or both. Of particular relevance in this context is the trapping of carbohydrates as or on food particles remaining in the mouth for considerable periods. 

Protein and starch digestion, on the other hand, have potent nonpancreatic compensatory mechanisms. Due to the compensatory action of salivary amylase and brush border oligosaccharidases, a substantial proportion of starch digestion can be achieved without pancreatic amylase. Similarly, protein denaturation and hydrolysis is initiated by gastric proteolytic activity (acid and pepsin) and continued by intestinal brush border peptidases, and is thus partly maintained even in the absence of pancreatic proteolytic activity. 

The basis of bacterial adhesion is given by the acquired pelhcle formation on tooth surfaces. This pelhcle is a thin ( 0.5-l pm) layer of several sahvary proteins with calciumhydroxide-binding properties. The most important such proteins are salivary amylase, cystatins (S, SA, and SN type), histatin (HRPl), mucine (MGl), acidic PRPs, statherin, and immunoglobulins (slgA) (4, 7). 

However, it has not been found possible to cause these chemical reactions to take place in the laboratory at the temperature of the human body, except in the presence of special substances obtained from plants or animals. These substances, which are called enzymes, are proteins that have a catalytic power for certain reactions. Thus the saliva contains a special protein, an enzyme called salivary amylase or ptyalin, which has the power of catalyzing the decomposition of starch into a sugar, maltose, The reaction that is catalyzed by salivary... 

Saliva is mixed with a food, such as potato, while the food is being chewed, and during the first few minutes that the food is in the stomach the salivary amylase causes the conversion of the starch into maltose to take place. 

It may be mentioned that the formation of D-glucose as a primary product is not characteristic of all a-amylases. Thus salivary amylase produces no D-glucose when free from maltase. The production of D-glucose and the peculiar shape of the curve of hydrolysis, therefore, seems to be characteristic of the malt a-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... 

Whereas /3-amylase and salivary amylase split the a-dextrins and starch at much the same rate, the malt a-amylase has a much slower action on the a-dextrins (Table V). 

Arrow-root starch (500 g.) in 8 liters of water containing 1 g. of sodium chloride was hydrolyzed at pH 6.5 with 50 ml. of saliva. After twenty-four hours, 50% of maltose had been formed. The reaction mixture was kept under toluene for thirty-two days. The reducing power then corresponded to 89% maltose. Fermentation experiments, however, showed that 63% maltose and 14% D-glucose had been formed, the latter by the secondary action of maltase. As mentioned above, the salivary amylase does not form D-glucose as a primary product but differs in this respect from malt a-amylase. The pancreatic enzyme is... 

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