An Update on Developments in the Field of Thiamin Diphosphate-Dependent Enzymes

The Jordan group's interest center on: E. coli (ec) and human (h) pyruvate dehydrogenase (PDHc), 2-oxoglutarate dehydrogenase (OGDHc) and 2-oxoadipate dehydrogenase (OADHc) complexes; and on 1-deoxy-D-xylulose-5-phosphate synthase (DXPS). The most important findings were: (1) the first components of OGDHc and OADHc and ecDXPS aerobically generated the ThDP-enamine radical species in “off-pathway” mechanism. (2) The pre-steady-state rate constants for conversion of pyruvate to all intermediates were determined on the entire E. coli PDHc. (3) The hydrogen–deuterium exchange MS (HDX-MS) method provided a snapshot of (i) the conformational dynamics of the full-length E. coli DXPS; (ii) interaction loci of the ecE1p-ecE2p subcomplex; (iii) the unique inter-component interaction sites in the hE1o-hE2o subcomplex, also complemented by chemical cross-linking MS. (4) Protein engineering using site saturation mutagenesis was applied to the first and second components of the ecOGDHc and led to formation of acyl-Coenzyme A with a variety acyl groups.