capabilities, so information on the specific structure of DPEPI is highly sought after in order to find viable inhibitors that could be taken along with these antibiotics to make them more effective. Earlier, beta-lactamase enzymes were thought to occur only in bacteria, where their probable function was in protecting the organisms against the action of beta-lactam antibiotics. These antibiotics exhibit selective toxicity against bacteria but virtual inertness against many eukaryotic cells (Adachi et al., 1990).[supplied by OMIM] Reaction Mechanism When hydrolyzing a substrate, DPEP1 goes through a tetrahedral intermediate, after which the bridging solvent attacks the face of the carbonyl carbon of the scissile peptide bond. Although DPEP1 shows preference for dipeptide substrates with D amino acids at the carboxy positions, it has been shown that DPEP1 can accommodate substrates with both D and L amino acids. Interactions Dipeptidase 1 has been shown to interact with KIAA1279. Cancer DPEP1 has been found to be highly expressed in colon tumor cells compared to normal colon cells—one study even found a ≥2 fold over-expression of DPEP1. Increased levels of DPEP1 have also been detected in colorectal cancer patients, suggesting that DPEP1 is a viable marker for disseminated colon tumor cells. References Further reading EC 3.4.13