Proteins in saliva

Question 1

Describe the salivary protein Mucin in terms of:

• Structure
• Role in saliva

Answer 1

Structure:
• It is a glycoprotein as it has a protein backbone with carbohydrates attached to its side chains
• Posttranslational modification (after protein formation, it undergoes further changes)

Role in saliva:
• Bacteria can stick to the mucin layer as it is sticky
• Because it is heavily glycosylated it holds water and is highly viscous, therefore it tends to form gels
• Contributes to the acquired pellicle formation

Question 2

Describe proline- rich proteins (PRP)

• Structure
• Role in saliva

Answer 2

Structure:
• Polymorphic (has different forms)

Role in saliva:
• High affinity for hydroxyapatite
• Also helps from the acquired pellicle

Question 3

Describe amylase in terms of:

• Which gland produces it
• When it is active
• Its role in saliva

Answer 3

Which gland produces it:
• Parotid gland

Active:
• At low pH

Function and role in saliva:
• Endoglycohydrolase: hydrolyses the glycose chains
• Aids in digestion by converting starch to maltose

Question 4

Describe lipase in terms of:

• Function
• Which gland produces it
• Role in saliva

Answer 4

Function:
• Hydrolyses medium to long chain triglycerides

Which gland produces it:
• Predominantly produced by minor salivary glands

Role in saliva:
Enables fat digestion in newborns

Question 5

Describe agglutinin in terms of structure and role in saliva

Answer 5

• Glycoprotein

* Causes agglutination of oral bacteria so that they can be removed by antibodies

Question 6

Describe salivary peroxidase and myeloperoxidase roles in saliva

Answer 6

• Breaks down reactive oxygen species such as hydrogen peroxide, to protect the body
• Antioxidants

Question 7

Describe lysozymes role in saliva

Answer 7

• Hydrolyses (breaks down) peptidoglycan, which is the outer cell wall of bacteria
• It is therefore, antimicrobial

Question 8

Describe lactoferrins role in saliva

Answer 8

• Scavenges and binds to iron so that bacteria cannot use it to grown and function properly
• It is therefore, antimicrobial

Question 9

List and describe the types of immunoglobulins present in saliva

Answer 9

Secretory IgA (sIgA):
• Is the dimeric form
• It is implicated in innate immunity
• Different from serum IgA (processed by salivary enzyme)

• IgG (product of acquired immunity) and IgM

Question 10

Describe histatins role in saliva

Answer 10

• Histidine rich peptide
• Active against Candida albicans and P. gingivalis (3 and 5)
• Binds to hydroxyapatite to reduce S. mutans adhesion (1)

Question 11

Describe statherin in terms of:

• Which gland it is produced by
• Its role in saliva

Answer 11

Which gland it is produced by:
• Parotid and submandibular glands

Role:
• It prevents the precipitation of calcium phosphate in saliva, maintaining a high calcium level in saliva available for remineralisation of tooth enamel and high phosphate levels for buffering.
• C terminus inhibits the growth of anaerobic bacteria

Question 12

Describe cystatins role in saliva

Answer 12

Cysteine protease inhibitors

Question 13

Describe the role of growth factors in saliva

Answer 13

• Help facilitate wound healing process