Salivary alpha-amylase (SAA)

 Salivary alpha-amylase (SAA)

It is the first enzyme encountered during the

digestion of carbohydrates. As food enters

the mouth and is chewed, the salivary

glands release saliva containing alphaamylase.

It continues to act for up to half an

hour in the interior of the food bolus after it

has arrived in the stomach. It is eventually

inactivated at the low pH produced by

gastric acid when it penetrates the food bolus. It can digest up to 50% of the

starch present in food.

Location of Production: Salivary alpha amylase, also known as ptyalin, is

produced and secreted by the salivary glands, specifically the parotid glands,

submandibular glands, and sublingual glands.

Digestive Function: Salivary alpha amylase initiates the digestion of complex

carbohydrates in the mouth. It breaks down starches into shorter

polysaccharide chains, such as maltose and maltotriose, by hydrolyzing

alpha-1,4-glycosidic linkages.

pH and Optimal Conditions: Salivary alpha amylase functions optimally at a

neutral to slightly acidic pH range of about 6.7 to 7.0. This pH range is

generally found in the mouth, allowing the enzyme to efficiently begin the

breakdown of carbohydrates during the chewing and mixing of food with

saliva.

Timing of Action: The activity of salivary alpha amylase starts as soon as

food enters the mouth. It continues its digestive action while food is being

chewed and mixed with saliva before reaching the stomach. 

Regulation: The secretion of salivary alpha amylase is regulated by the

autonomic nervous system, specifically the parasympathetic nervous system.

The presence of food in the mouth and the stimulation of taste receptors

trigger the release of saliva, which contains salivary alpha amylase.

Clinical Significance: The measurement of salivary alpha amylase levels can

be used in some research and clinical settings to assess stress responses. The

activity of salivary alpha amylase has been linked to the body's stress

response system, and its levels can indicate changes in sympathetic nervous

system activity.

Structural Properties: Salivary alpha amylase is a glycoprotein, similar to

pancreatic amylase, with carbohydrate chains attached to its protein structure.

Its active site is also formed by a catalytic cleft, allowing it to interact with

starch molecules and initiate their hydrolysis.

Individual Variation: The activity of salivary alpha amylase can vary

between individuals due to genetic factors and environmental influences.

Some people may have higher or lower levels of salivary alpha amylase,

leading to differences in their carbohydrate digestion efficiency21.