Edman degradation on in vitro biosynthesized peptidoglycans from Staphylococcus epidermidis

Edman degradations were performed on the pentapeptide bridges of peptidoglycans which were biosynthesized in vitro by using six different species of seryl-transfer ribonucleic acid (tRNA). The ratio of glycine to serine in each of the five bridge positions varied with the concentration of crude glycyl-tRNA contained in the reaction mixtures, and serine appeared to be incorporated in a random manner. No single species of seryl-tRNA could be identified as the one active in in vivo pentapeptide bridge synthesis; however, it can be speculated that seryl-tRNA(s) from category I could be involved in the in vivo nonrandom incorporation of serine in the bridge.