2-OXO ACID DEHYDROGENASE MULTIENZYME COMPLEXES - THE CENTRAL ROLE OF THE LIPOYL DOMAIN

2-Oxo acid dehydrogenase complexes are composed of multiple copies of at least three different enzymes, 2-oxo acid dehydrogenase, dihydrolip oyl acyltransferase and dihydrolipoamide dehydrogenase. The acyltransf erase component harbours all properties required for multienzyme catal ysis: it forms a large multimeric core, it contains binding sites for the peripheral components, the acyltransferase active site and mobile substrate carrying lipoyl domains that couple the active sites. In the past years these complexes have disclosed many of their secrets, prov iding currently a wealth of information on macromolecular structure, a ssembly and symmetry, active-site coupling, conformational mobility, s ubstrate specificity and metabolic regulation. In this review we will discuss developments concerning the structural and mechanistic feature s of the 2-oxo acid dehydrogenase complexes, with special emphasis on the structure and role of the lipoyl domains in the complex.