biochem2 Flashcards
Which cells produce collagenase in HEALTH?
Fibroblasts
Which cells produce collagenase in DISEASE?
polymorphonucleocytes macrophages
Some bacteria can also secrete collagenase
Name the enzyme that breaks down collagen
Collagenase
What type of enzyme is collagen?
It is a matrix metalloprotease (MMP)| It is an Endopeptidase
What link has been suggested between TIMP and periodontal disease?
there has been some suggestion that TIMP may be downregulated in certain patients tipping the balance towards periodontal breakdown.
How much faster is collagen synthesis in PDL compared to subdermal gingiva?
2 times
How much faster is collagen synthesis in PDL compared to Skin
4 times faster
How much faster is collagen synthesis in PDL compared to Alveolar bone?
6 times fater
How much faster is collagen breakdown in PDL compared to the gingiva?
5 time faster
How much faster is collagen breakdown in PDL compared to skin?
15 times faster
How much faster is collagen breakdown in PDL compared to alveolar bone
6 times faster
What is the half life of collagen in the PDL, gingiva and skin
PDL: 40 minsGingiva: 80 minsSkin: 360 mins
What model can we use to help us understand disease progrssion within the periodontal ligament ?
By using sheep
What do some sheep suffer from?
A condition called broken moth
What is broken mouth clinical similar to?
To rapidally progressing periodontitis in men
What happens ti sheep suffering from broken mouth?
Their quickly lose their lower teeth
What happen to the amount of collagen in sheep suffering from broken mouth?
there was an overall loss of collagen from the gingiva and periodontal ligament with disease
What happens to the activity of gelatinase in sheep suffering from broken mouth?
There was an increased activity of the enzymes in the diseased tissue
What 3 things did scientist look at in sheep with broken mouth disease?
Gelatinase enzyme activity Collagen levels GCF was tested
What were scientist looking fro when they tested the GCF of disease sheep?
looked for evidence of any collagen fragments that might be present in the sulcus
What was the underlying hypothesis scientists were working around when they were looking at sheep with broken mouth disease?
The underlying hypothesis was that if there is increased collagen degradation occurring during episodes of active periodontal disease, then some of those fragments might “wash out” in to the gingival crevice due to the increase fluid outflow that occurs with gingival inflammation.
What did southern blotting of the GCF in sheep with broken mouth disease show?
detected fragments of collagen in the crevicular fluid of diseased animals but not in healthy animals.
Has a strong correlation between PDL conditions in sheep with broken mouth disease and humans with periodontitis been found?
No a strong correlation has not been found
Where is the ground substance found?
It is present as the cement around the fibres in all connective tissues, including periodontal ligament
What does the ground substance comprise of?
- Non-collagenous proteins (NCPs)2. Hyaluronic Acid (GAG)3. Proteoglycans (PGs)
Give an example of a non collagenous protein?
fibronectin which is a glycoprotein
What are proteoglycans made up of?
Proteoglycans are monomers made up of a protein core to which is covalently bonded to a chain(s) of glycosylaminoglycans (GAGs)
What are glycosylaminoglycans?
GAGs are carbohydrate heteropolymers, made up of repeating disaccharide sub-units. Each disaccharide sub-unit is comprised of a hexosamine sugar plus a uronic acid residue
Are glycosylaminoglycans hydrophilic or hydrophobic?
They are highly HYDROPHILIC and attract and bind many water molecules as part of their extended structure
What 2 forms can chondroitin sulphate exist in?
chondroitin-6-sulphate| chondroitin-4-sulphate
What is the difference between chondroitin-6-sulphate and chondroitin-4-sulphate?
In chondroitin-6-sulphate the sulphate ion is attached to the 6th carbonIn chondroitin-4-sulphate the sulphate ion is attached to the 4th carbon
Which if the 2 forms of chondroitin sulphate is more abundant in hard tissue?
Chondroitin-6-sulphate
Which if the 2 forms of chondroitin sulphate is more abundant in the PDL?
Chondroitin-4-sulphate
Name the 2 GAGs we need to know
chondroitin sulphate| dermatan sulphate.
What is the difference between chondroitin sulphate and dermatan sulphate?
the form of uronic acid in dermatan sulphate is an epimer called iduronic acid
What are proteoglycans aggregates?
They are huge aggregated macromolecular structures that arise when proteoglycans are non covalently bonded to a link protein and hyaluronan
What does the number do GAG side chains bound to a single protein core depend on?
depends upon the specific proteoglycan
Describe what aggrecan is
It is a large, aggregating proteoglycan that looks like a bottle brush structure under the transmission electron microscope
What type of proteoglycans does the PDL contain ?
both small (unaggregated) and large (usually aggregated) proteolycans.
Name the 2 SMALL proteoglycans found most abundantly in the PDL
mainly two small leucine-rich proteoglycans| decorin and biglycan
What is decorin?
is a small proteoglycan that is rich in dermatan sulphate GAGs
Seen to ‘decorate’ collagen fibres
Name the BIG proteoglycans found most abundantly in the PDL
Versican
What is Versican?
A large proteolglycan that is rich in chondroitin sulphate.
Mr of SLRPs core protein
36-45 KDa
Do small proteoglycans (SLRPs) aggregate?
They tend not to aggregate
How many GAG side chains does decorin have?
1 called dermatan sulphate
Where is biglycan more abundant?
In the alveolar bone
How many GAG side chains does biglycan have ?
2| either both chondroitin sulphate or one hondroitin sulphate and the other dermatan sulphate.
Describe versicans protein core
Many GAGchains are attached to it| It is bigger than decorin
List the functions of proteoglycans and GAGs in connective tissues
- Collagen fibril orientation/diameter2. Control of Mineralisation3. Generation of the Eruptive Force
How does decorin interact with collagen?
Decorin is able to interact closely with collagen fibrils and regulate their growth and hence their final fibril diameter within the tissue
Where is Dermatan sulphate found?
Mainly in decorin
What is Dermatan sulphate associated with in regards to collagen?
It is associated with large collagen fibrils (200 nm in diameter)
What is chondroitin sulphate associated with in regards to collagen?
associated with small fibrils
What did Parrys (1972) investigations show about collagen fibres?
Used rabbits and found as tissue aged, the average size of collagen fibrils increased in diameter with more glycosaminoglycans present.
As connective tissues mature, total GAG content decreases and the proportions of CS: DS shift
CS predominates in foetal tissue; DS predominates in mature tissues
PDL= small fibrils within ground substance which is relatively CS rich (DS still predominates in healthy tissues)
According to Parrys investigation what happens to the number of Dermatan sulphate as we age?
It increases with tissue age| Becomes the most abundant GAG (80% of all tissue GAG present)
According to Parrys investigation what happens to the number of Chondroitin sulphate as we age?
Almost all chondroitin was lost in mature tissue, when collagen fibrils were large.
What are proteoglycans responsible fro directing with regard to collagen fibrils?
Proteglycans are responsible for directing the orientation of collagen fibres throughout the tissue (important for tissue function)
How do proteoglycans control fibrillogenesis?
via their ability to bind to| collagen fibrils.
What may the ability of GAGs being able to inhibit and control mineralisation be related to ?
their high negative charge binding mineral
How do GAGs control mineralisation?
GAGs can inhibit deposition of hydroxyapatite crystals in soft connective tissues
What does the removal of GAGs from the PDL lead to?
leads to deposition of| hydroxyapatite crystals in and around collagen fibrils. Stops teeth being joined to bone as mineralised tissues+mineralised tissues = strong hold so risk of jaw breaking when extracting tooth
Why are proteoglycans and GAGs need for tooth eruption?
Related to their large hydrodynamic volume.
Inc conc of GAG
What happens to the amount of collagen when someone gets periodontal disease?
It decreases
What happens to the total Dermatan sulphate content in the PDL of a sheep with periodontal disease?
It decreases
What happens to the total Chondroitin sulphate content in the PDL of a sheep with periodontal disease?
It increases
What happens to the total decorin content in the PDL of a sheep with periodontal disease?
It decreases
What happens to the total Versican content in the PDL of a sheep with periodontal disease?
Increases
Summarise how the biochemistry of the PDL changes with periodontal disease?
- Total sulphated GAG content increases
- Percentage of Dermatan sulphate decreases
- Decorin decreases
- Percentage of Chondroitin sulphate increases5. Versican increases6. Collagen content decreases7. Gelatinase activity increases
SLRPs don’t have what compared to large proteoglycans
No hyaluronan or link protein
What is the relationship between aggravate size and collagen fibre size?
Inversely proportional
Bigger aggregates = smaller collagen fibres
Compare fibril diameter between foetal connective tissues, PDL, and mature connective tissue
FCT: 20-50 nm
PDL: 40-50 nm
MCT:100-250nm
What % the extracellular matrix is made of ground substance in the foetal connective tissue, PDL, and mature CT
FCT- 70% of ECM vol
PDL- 65% of ECM vol
MATURE- Much less (varies)
