The two common polymorphic forms of human NRH‐quinone oxidoreductase 2 (NQO2) have different biochemical properties

There are two common forms of NRH‐quinone oxidoreductase 2 (NQO2) in the human population resulting from SNP rs1143684. One has phenylalanine at position 47 (NQO2‐F47) and the other leucine (NQO2‐L47). Using recombinant proteins, we show that these variants have similar steady state kinetic parameters, although NQO2‐L47 has a slightly lower specificity constant. NQO2‐L47 is less stable towards proteolytic digestion and thermal denaturation than NQO2‐F47. Both forms are inhibited by resveratrol, but NQO2‐F47 shows negative cooperativity with this inhibitor. Thus these data demonstrate, for the first time, clear biochemical differences between the variants which help explain previous biomedical and epidemiological findings.