Organic components of Saliva Flashcards
Does parotid have higher protein secretions. than sublingual ?
Yes
Is protein saliva content lower than found in plasma?
yes
What are saliva protein properties?
- Lubrication
- Antimicrobial
- Enzymes
What are salivary mucins?
glycoproteins that contain 0- & N- linked sugars
What are O-linkages?
O-acetylgalactosamine
What are N-linkages?
N-acetylglucosamine
What do O linked sugars attach to?
serine and threonine amino acids
What do N linked sugars attach to?
Asparagine amino acid
what are carbohydrates attached in N-type linkage?
OLIGOSACCHARIDES
What does attachment of Sialic acid on salivary mucins do?
confer negative charge so extend structure of protein
- repulsion between charges between folds in chain
How are mucin oligomers formed?
cysteine residue form covalent cross links vis -SH group
What are 2 types of mucin secreted by saliva?
MG1- High molecular weight mucin
MG2-Low molecular weight mucin
What does MG1 do?
form complexes w/ salivary proteins
What does MG2 do?
bind to oral streptococci
What are salivary proteins?
Amylase
Proline rich proteins
Statherin
Histatins
What salivary mucins do ?
- lubrication
- speech/swallow
- barrier to harmful microbes
- bind to teeth
What is Statherin?
small protein that inhibits calcification of HAP
What does high conc. of mineral ions mean?
calculus (calcified tar/plaque)
what can calculus lead to?
blocked salivary duct
periodontal disease
How does statherin work?
Bind to HAP so HAP cant bind to Ca
What produces statherin?
acinar cells
What are Proline rich proteins?
reduces HAP growth and is component of pellicle
What mainly secretes PRPs?
Submandibular secretion
What do PRPs prevent?
pathogens by binding to mineral to stimulate harmless microorg. colonisation instead of pathogens
What do statherins and PRPs role in?
unwanted mineral deposition and growth
What are Histatins?
defence peptides rich in Histidine amino acid
Why do histatins have a buffering capacity?
pKa of side chains= neutral
What are functions of Histatins?
- Active against S.Mutans (caries)
- Bind to Ca so no calcification of HAP
- on pellicle
What are immunoglobins?
proteins for body defence against pathogens
What is main Immunoglobin in saliva?
SigA,
What is SigA
IgA differentiates via secretory component
What happens when Immunoglobins bind to antigens?
agglutination so easier for bacteria to be swallowed
What is salivary amylase dependant on?
Calcium
What is amylase activated by?
Chloride ions
What gland secretes amylase?
Parotid
What does amylase do?
digest Carb. via hydrolysis of 1,4 glycosidic bond to form maltose disaccharides
What can’t amylase break down?
sucrose or polysaccharides w/ other glycosidic links
What is lysozyme?
Muramidase enzyme
What is a muramidase enzyme?
originate from striated duct of salivary gland
What does lysozyme do?
hydrolysis of 1,4 glycosidic bond between N-acetylmuramic and N-acetylglucosamine in bacteria cell wall
What bacteria cells does lysozyme target?
Bacteria tagged with SigA
What can lysozyme be found?
HAP and found in pellicle
What does Salivary Peroxidase enzyme do?
catalyse H202 + thiocyanate to form antibacterial 0SCN-
What does lactoferrin antibacterial protein do?
binds to Fe3+ so bacteria can’t use
What do Cystatins do?
inhibit bacterial proteases so protect soft tissue of mouth
Where can cystatins be found?
Pellicle and Bound to HAP
What are pH rising factors?
Urea
Tetrapeptide Sialin
how do factors rise pH?
microorg. in plaque metabolise urea and sialin to produce ammonia so neutralise plaque acid
