- A heteropolymer of glycan chains cross-linked by amino acids - Unique to bacteria
Is peptidoglycan found in all bacteria? Is it found in animal or plant cells?
- No, almost all, but not mycoplasma - Not found in animal or plant cells
Name the amino acid sugar components of peptidoglycan. Describe the structure of the chain
- The sugars: MurNac, GlcNac (a repeating disaccharide w/ beta 1,4 linkage) - The disaccharide has a tetrapeptide side chain - The peptide side chains are crossed linked together through a pentaglycine bridge between two disaccharide units.
Describe the differences in structure of the cell envelope in Gram positive and Gram Negative bacteria
Gram +: May have a capsule, protein, teichoic acids, polysaccharides, etc. on outside, then a thick cell wall (peptidoglycan), then a cytoplasmic membrane Gram -: May have a capsule, then outer membrane, then small peptidoglycan cell wall, then cytoplasmic membrane
What is the Park nucleotide? How is this different in Gram - bacteria?
- The MurNac pentapeptide - MurNac- UDP w/ L-ALA--D-Glu--L-LYS--D-ALA--D-ALA - In Gram - , the pentapeptide is MurNac w/ ALA--GLU--DAP--ALA--ALA
How are the cross links between the peptide side chains different in Gram - and Gram + bacteria?
- In gram + bacteria, the L-LYS in one peptide chain is attached to the fourth amino acid (D-ALA) of another peptide chain through a pentaglycine bride
- In gram - bacteria, the DAP of one peptide chain is bound to the fourth D-ALA of another chain