Probing the acetaldehyde-sensitivity of 2-deoxy-ribose-5-phosphate aldolase (DERA) leads to resistant variants

The 2-deoxy-d-ribose-5-phosphate aldolase (DERA) is a synthetically attractive enzyme because of its ability to perform CC-couplings stereoselectively, the enzyme uses acetaldehyde as nucleophile and thus produces true aldols rather than ketols, and may add two acetaldehyde molecules onto one electrophile. However, DERA produces crotonaldehyde as side reaction from acetaldehyde which is then an irreversible inhibitor forming a covalent Michael-adduct within the active site in particular with cysteine 47 (Dick et al., 2016). This inhibition can be resolved by mutating C47 to non-nucleophile amino acids. Still, the inhibition is not an on-off-feature and the present mutagenesis study illustrates that there must be a C47-independent inactivation mechanism. As a practical result: The virtually fully resistant mutant C47L was found, which shows no loss in stereoselectivity, - this renders this variant as promising catalyst.