Structures and molecular kinetic models of function of 2-oxo acid dehydrogenase complexes were analyzed. It was suggested that identical protein subunits in the multienzyme complexes as in the structure capable of self-assembly have identical contacts with the neighbors and identical environment. By sharing the enzyme aggregate subunits into distinct conformational classes the peripheral components were demonstrated to be arranged on the core so that the entire complex would have a definite symmetry. The number of the conformational classes is specified by the architecture of the core and considerations of symmetry. The results have allowed us to consider the mechanisms of functioning of the complexes. Specific examples are discussed.