Chemistry Reference
In-Depth Information
17
19
18
synergistically. The binding of type A streptogramins causes a conformational
change in the 50S ribosome that increases the activity of the type B streptogramins
by 100-fold, inhibiting bacterial cell growth. Each type also shows bacteriostatic
effects when administered separately. Type B streptogramin prevents the exten-
sion of protein chains, causing the release of incomplete peptides, and can bind
to ribosomes during any step of the protein synthesis (14). An example of a type
A streptogramin is virginiamycin M
1
(
19
), whereas pristinamycinI
A
is a type B
streptogramin (
20
).
3.1.3 Peptide Antibiotics
Peptide antibiotics are cyclic or polycyclic glycosylated structures that are active
against gram-positive bacteria. They can inhibit cell wall synthesis by prevent-
ing the incorporation of N-acetylmuramic acid and N-acetylglucosamine into
the peptide subunits of peptidoglycan. Common examples include vancomycin
(produced by
Amycolatopsis orientalis
)(
21
), teicoplanin (synthesized by
Actino-
planes teichomyceticus)
(
22
), and ramoplanin (extracted from
Actinoplanes
sp.
ATCC 33076) (
23
).
