Kinetic mechanisms of mitochondrial carriers catalysing exchange reactions.

ABSTRACT

The single-binding site or ping-pong mechanism is widely accepted for exchange reactions, catalysed by mitochondrial carriers. However, when the most relevant approach to discriminate between mechanisms, i.e., kinetic study is used, the ping-pong mechanism is eliminated in favour of the sequential or ternary complex mechanism implying two binding sites simultaneously accessible to both internal and external substrates. This is the case for the oxoglutarate carrier, the aspartate/glutamate carrier and there are very strong presumptive evidences for the adenylic carrier.