Two molecules of methylglyoxal react in vitro with one molecule of arginine to form a pyrimidinium adduct or with two molecules of lysine to form an imidazolium-based crosslink.

Adipoyl-6-aminopenicillanic acid 5 was incubated with recombinant DAOCS and the resulting cephalosporin isolated. Adipoyl-6-aminopenicillanic acid 5 is approximately 735 times less efficient as a substrate for DAOCS in vitro (as judged by kcat/Km) than penicillin N 1.