ORGANIC COMPONENT Flashcards
properties of salivary proteins
- lubricating properties
- anti-microbial
- mineral binding properties
role of salivary mucins
- oral lubrication
- facilitates speech and swallowing
- bacterial agglutination
- direction of bacterial attachement
- barrier to demineralisation
- protects hard and soft tissue from damage
how are carbs added to the proteins
by covalent attachments to the amino acid side chain
two types of covalent bonds that form
N linkages and O linkages
which linkage is more abundant in salivary mucins
- o linkages
o linked sugars are added to
serine amino acid residues
and
Thronine amino acid residues
n linked sugars are added to
amide nitrogen of side chain of the asparginie
When do asparagine residue accepts sugars?
An asparagine residue only accepts sugars in a consensus sequence
e.g.
Asn - X - Thr
Asn - X – Ser
Carbohydrates that attach to Asparagine have a common pentasaccharide sequence
Further sugars may be added to this core Sialic acid -ve charge on mucin extended structure for proteins inc. repulsion between chains
n linked oligaosaccharides- common structure
3 mannose and 2 n acetylglucosamine residues- to which further sugars can be attached
describe mucin structure
Mucins have a carboxyl and an amino end which are rich in cysteine form cross chains with other mucin monomers, linear mucins and mucin oligomers
Central portion rich in serine + threonine saturated with O-linked oligosaccharide
oligomers
similar to polymers but with far less repeating units
two types of salivary mucins
MG1 and MG2
MG1
- high molecular weight
- mixture of 3 different gene products
- larger than MG2
- oligemeric strucutre
- made from many mucin monomers joined by S-S bonding (from cysteine)
- Also binds to other salivary proteins (amylase/PRPs)
MG2
- dervies from 1 single gene
- single monomer
- lower molecular weigh that MG1
- binds to oral pathogens and yeast
- purified MG2 can kill oral bacteria
statherin
- important component of salivary pellicle
- unique amino acid primary sequence-high proline content
- small molecular weight
- high negative charge