TABLE 1.

Composition of branched peptidoglycan peptide cross-bridges in Gram-positive organisms (2, 7)

Bacterial species	Peptide cross-bridge composition (from ε-l-Lys to d-Ala)
E. coli	None (direct cross-link: meso-diaminopimelic acid → d-Ala)
Staphylococcus aureus	Gly-Gly-Gly-Gly-Gly
S. pneumoniae	l-Ala-l-Ala or l-Ser-l-Ala
W. viridescens	l-Ala-l-Ser
Enterococcus faecalis	l-Ala-l-Ala
Enterococcus faecium	d-Asxa
Streptomyces coelicolor	Gly

^ad-Aspartate or d-asparagine.