Interview with Kenneth A. Johnson, University of Texas at Austin, USA recorded at BEILSTEIN ENZYMOLOGY SYMPOSIUM – Enzymes in Transformation and Signalling Rüdesheim, Germany, 19 – 21 September 2017 Kenneth Johnson is talking with Carsten Kettner about the appropriate application of terminology in enzymology. Although this terminology is well defined and recommended by, e.g. IUBMB, the major reasons for the confusion caused by the often falsely used terms seems to be laziness of authors and lack of sound training and education. Ken explains the parameters that affect the efficiency of enzyme catalysis: The efficiency of enzymes derives from their flexibility and dynamics. Intramolecular movements within an enzyme result in high specificity in selecting the favourite substrate over the mismatch. He describes this using the example of DNA polymerases where the polymerase has to be fairly discriminatory over very small differences in the structure of the correct base versus the mismatch, and those enzymes have very high specificity at very low error rates. However, mismatch in DNA replication can also have evolutionary impact which can be studied on HIV which can be considered a moving target that alters rapidly recognition sites to hide itself from the immune system until it collapses and the patient gets AIDS.