Lecture 7 Better Antibiotics
Friday, 28 September 2012
Kills bacteria that cause syphilis
specific against treponemia pallidum
Antibacterial acting on bacterial wall:
β lactam antibiotics -penicillin
successful, non toxic because humans do not have equivalent to cell wall so not effected by
bacteria can produce B-lactamase that can combat B lactams antibiotic effect
Penicillin attacking cell wall :
Cell wall contains polymer of 2 monomer units NAM and NAG and B-1,4 linkages between
NAM and NAG
D amino acids present, not present in humans, this is targeted by penicillin.
Affects the assembly of the cell wall causing the bacteria to become osmotically unstable
causing the cell to burst and die.
This is due to the O=C-N bond in the beta lactam ring. this interferes with cell wall protein
different R groups for different types of penicillin.
Inhibits transpeptidase preventing crosslinks from forming
terminal D-ala-D-ala peptide bond broken - new peptide bond formed between COOH of D-ala
and NH2 of glycine
The C-N of penicillin is a structural analogue of the peptide bond
Park nucleotides are the units released when the bacterial cell lyses. Remnants of the cell wall
UTP acts as the carrier for the assembly of glycoproteins that form the bacterial cell wall.
P acts as a carrier for polypeptide glycan synthesis
Chain of glycine's can be linked to amino or carbon groups
found in cell walls (peptide glycan's)
Enzyme produced by bacteria as a resistance to B-lactam
Resistance to penicillin by hydrolysing the b-lactam bond preventing disruption of the cross
the use of different penicillin variants may help as some are less susceptible to B-lactamase
Cephalosporins usually have a resistance to B-lactamase
The biochemical action of B-lactamase: hydrolyses C-N bond creating COOH and NH2+ making
B lactam compound Non antibiotic, inhibits