Question

What are enzymes? Name an enzyme which is present in saliva and state its function.

Answer 1

Hint: Enzymes are the globular proteins that catalyze a biochemical reaction. The enzymes catalyze the reactions at a very high rate. The enzyme which is present in the saliva is released by the salivary glands and it helps in the process of food digestion.

Complete answer:
Almost all enzymes are protein. They also have secondary and primary structures.
The tertiary structure of an enzyme contains a crevice called an active site. The active site is the crevice where the substrate fits and due to active sites, the enzymes catalyze reactions at a very high rate and can be reused.
Enzymes get denatured at a very high temperature.
Enzymes having active sites converts a substrate into a product. The substrate binds to the active site of an enzyme and the formation of an intermediate enzyme-substrate complex occurs and finally, the substrate is released from the active site and is converted to a new product. It is shown as follows :
$ENZYME = SUBSTRATE \Leftrightarrow ENZYME - SUBSTRATECOMPLEX \Leftrightarrow ENZYME + PRODUCT$
The enzyme which is present in the saliva is called salivary amylase or is also known as ptyalin. Salivary glands present in the buccal cavity release this enzyme.
The salivary glands help in the digestion of food.
The teeth and the tongue with the help of saliva masticate and mix up the food.
Mucus in saliva helps in lubricating the food particles into a bolus.
The saliva contains the electrolytes and enzymes. This enzyme has the hydrolytic action on carbohydrates and converts starch into maltose.
The pH of the salivary amylase is $6.8$.

Note:
There are various factors affecting enzyme activity which are temperature and pH, the concentration of substrate.
Enzymes are classified into 6 classes which are oxidoreductase, transferases, hydrolases, lyases, ligases, isomerases, based upon their functions.