cell wall antibiotics Flashcards
1
Q
Describe the structure of peptidoglycan
A
- 2 repeating sugar units n-acetyl glucosamine & n-acetyl muramic acid joined together with a B-1,4 glycosidic bond
2
Q
Why is peptidoglycan an idea target for antibiotics ?
A
- it’s unique to bacteria & occurs in almost every bacteria
3
Q
What are the building blocks of peptidoglycan?
A
- two sugars = n-acetyl glucosamine & n-acetyl muramic acid
- also involves amino acids to make up cross bridges
4
Q
Where are the building blocks of peptidoglycan drawn from?
A
- amino acids are drawn from central metabolism
- 2 sugars are synthesised from simple sugars
5
Q
Describe the sugar back bone
A
- provides little rigidity of strength so its cross linked by amino acid bridges to provide load-bearing capability
6
Q
Describe the cross linked backbone
A
- amino acid chains attached to the n-acetyl muramic acid residues form bridges (transpeptide bridges)
- this gives strength in a second dimension - holding chains of sugars together
7
Q
How can adjacent sugar sheets be linked ?
A
- unbridged M sugars can then form transpeptide bridges with M sugars in sheets above & below giving 3D structure
8
Q
Describe transpeptidase enzymes
A
- usually found as membrane bound enzymes
- catalase reactions outside the cell
- multiple types in bacteria
- spatially organised
9
Q
Describe Transglycoslyase enzymes
A
- splits the pyrophosphates bond between bactoprenol & N- acetyl muramic acid of glycol chain.
- then forms a glycosidic bond between C1 of the M of old chains & C4 of the G of the precursor
10
Q
What are PBP’s?
A
Penicillin Binding proteins
11
Q
Describe PBP’s
A
- enzymes responsible for transglycosylation reactions, transpeptidase & endopeptidase reactions
- some PBP’s have dual transglycosy
