Question

Saliva has the enzyme
A. Pepsin
B. Ptyalin
C. Trypsin
D. Renin

Answer 1

Saliva, commonly referred to as spit, is an extracellular fluid produced and secreted by salivary glands inside the mouth. In humans, saliva is 98% water along with electrolytes, mucus, white blood cells, epithelial cells, enzymes (such as amylase and lipase), antimicrobial agents such as secretory IgA and lysozymes.

Complete Answer:
The enzymes found in saliva are essential in digestion of dietary starches and fats. These enzymes also play an important role in breaking down food particles trapped within dental crevices. Thereby, it contributes in protecting the teeth from bacterial decay. Saliva contains the following enzymes:
1. α-amylase or ptyalin: secreted by the acinar cells of the parotid and submandibular glands; it initiates digestion of starch before the food is even swallowed. It has a pH optimum of 7.4.
2. Lingual lipase: It is secreted by the acinar cells of the sublingual gland and has a pH optimum around 4.0. It is not activated until entering the acidic environment of the stomach.
3. Kallikrein: It is an enzyme that proteolytically cleaves high-molecular-weight kininogen to produce bradykinin (a vasodilator); it is secreted by the acinar cells of all three major salivary glands.
Antimicrobial enzymes that kill bacteria:
1. Lysozyme
2. Salivary lactoperoxidase
3. Lactoferrin
4. Immunoglobulin A

Thus, option (B) ptyalin the correct answer. It breaks starch into maltose and dextrin. It will break large, insoluble starch molecules into soluble starches (amylodextrin, erythrodextrin, and achrodextrin) to produce successively smaller starches and ultimately maltose.

Note:
Although found in many tissues, ptyalin is most prominent in pancreatic juice and saliva. Each of the types have its own isoform of human α-amylase. They behave differently on isoelectric focusing and can be separated in testing by using specific monoclonal antibodies. In humans, all amylase isoforms are linked to chromosome 1p21.