A novel α-N-acetylgalactosaminidase family with an NAD+-dependent catalytic mechanism suitable for enzymatic removal of blood group A antigens

AbstractEnzymatic removal of blood group A and B antigens from the surface of red blood cells to develop universal blood was a pioneering vision originally proposed more than 25 years ago. A great variety of enzymes, potentially suitable for enzymatic conversion of red blood cells, has been described since, but the process has not been economically viable because of the poor kinetic properties and low pH optimum of enzymes. Recently, the identification of two new families of bacterial glycosidases with enhanced kinetic properties for the removal of A and B antigens at neutral pH marked a milestone in the field of transfusion medicine (). Here we present a detailed structural analysis of Elizabethkingia meningosepticum a-N-acetylgalactosaminidase (NagA) shown to efficiently cleave the A antigen. NagA, a member of glycoside hydrolase (GH) family 109, employs an unusual catalytic mechanism involving NAD+. Comparison of the active-center structure with that of members of GH family 4 reveals a striking degree ...