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Substitution of dehydroalanine residue at position 5 in nisin by alanine leaves nisin's bacterial growth inhibiting activity unaffected. However, it reduces its activity as an inhibitor of the outgrowth of spores. The bacterial growth and spore outgrowth inhibitive activities of both nisin and subtilin are based on different structure-activity relationships and therefore the two activities arise from different molecular mechanisms. The presence of dehydroalanine residue at position 5 is unnecessary for inhibiting Lactococcus lactis and Micrococcus luteus growth.

Site-directed mutation combined with isotope-edited 1H nuclear magnetic resonance spectroscopy was used to analyze chloramphenicol acetyltransferase (CAT) complexed with diacetyl chloramphenicol. 1H signals were detected from the methyl groups of the acetyl substituents of the substrate. Molecular modeling showed that these methyl groups interact with a number of residues in the chloramphenicol-binding region of CAT. Site-directed mutation revealed that the tyrosine residue at position 25 of CAT is close to the acetyl substituent at position 3 of the substrate.