Salivary Amylase: What is it? Description, Function, Process, General Structure, Catalyzed Reaction and Interactions

How does saliva help break down food?

It contains a special enzyme called salivary amylase that does the job.

Description and function

When you eat something, when does your body start to digest it? Many people think it is after food enters their stomach. However, this assumption is incorrect.

Digestion actually begins the moment food enters your mouth and comes into contact with salivary amylase. This has to do with the enzymes in your mouth.

Enzymes are groups of molecules that help speed up chemical reactions. If you see a word that ends in ‘handle’, you know that you are dealing with an enzyme.

Salivary amylase (also α-amylase 1, ptyalin) is an enzyme found in human saliva. This enzyme helps break down the starches in your food.

Starch is a large compound that is broken down into its smaller sugar subunits by salivary amylase. This process is called chemical digestion or the chemical breakdown of food.

While it begins in the mouth, chemical digestion continues throughout the digestive system. The other type of digestion is mechanical, which refers to the physical breakdown of food, which includes chewing and moving the stomach to churn it.

It can break down storage carbohydrates, such as starch and glycogen, by separating 1,4-α-D-glucoside bonds into their components. In many vertebrates, as in humans, carbohydrate digestion begins with the production of the enzyme in saliva.

The pancreas produces other isoforms, called pancreatic amylase.

The genes that encode the isoforms are called AMY1A, AMY1B, and AMY1C. They differ only slightly from each other.

According to recent studies, isoforms have been formed by copying, and only recently. It is the first example of genetic adaptation to altered eating and nutritional habits in humans.

Process

When food is chewed in the mouth, it is reduced to small fragments that mix with the saliva produced by the three pairs of salivary glands (parotid, submandibular and sublingual).

Saliva is a neutral or slightly alkaline liquid, containing water, mucus, and enzymes (salivary amylase or ptyalin).

The submandibular and sublingual glands secrete thicker saliva that contains the enzyme mucin. The other enzyme in saliva is ptyalin, which partially digests starches and converts them to maltose (a type of sugar).

Water moistens food, mucus lubricates it, and amylase catalyzes the hydrolysis of starch (polysaccharide) that transforms it into simpler sugar molecules (oligosaccharides and monosaccharides).

Saliva also dissolves some molecules that are taken up by taste receptors on the taste buds of the tongue (allowing recognition of flavors).

General structure

The structure consists of a single polypeptide chain of 496 amino acids that can be divided into three domains. It houses the active site and contains three catalytic residues: Asp197, Glu233, and Asp300.

The neon structures are GLC sugars used for crystallography purposes and demonstrate the binding region.

The hydrophobic ligands Arg337, Arg195, and Asn298 function as binding sites for chloride ions, which are required for full catalytic activity.

These binding sites also contain nearby hydrophobic residues (Phe265 and Phe295) that aid in the catalytic activity of the enzyme. Only one chloride ion and calcium ion bind per molecule.

It is a calcium metalloenzyme and therefore cannot function efficiently in the absence of calcium. The ion serves as a stabilizer during hydrolytic activity and is held in place by residues Arg158, Asn100, Asp167, and His201.

It is organized in a Beta structure and its function is still unknown.

Catalyzed reaction

The Poly-D-glucose is ground until only maltose and maltotriose are present. The enzyme can also handle 1-6 branched sugar chains (amylopectin); additional end products are limit dextrins.

Interactions

The Ptyalin former serves for force dissection. This decomposition process can be severely hampered by certain foods, such as fruits that contain acids.

As a result of this improper breakdown of starch by inactivating ptyalin, it can lead to starch fermentation in the gastrointestinal tract and resulting discomfort such as bloating (flatulence).