Amino Acids and the Mitochondria

This chapter describes some of the important physiological functions of amino acids in the mitochondria and the alterations caused by specific pathologies. To some extent all of the featured items are dependent upon the movement of amino acids across the highly selective permeability barrier that is the inner mitochondrial membrane. The performance of this transport by specific carriers is the subject of the first section. Once inside the mitochondrial matrix the amino acids become involved in a bewildering number of critical metabolic pathways. The second section elaborates on two of the most significantly namely: The malateasparate shuttle essential for the transfer of reducing equivalents between the cytoplasm and the mitochondria; and the urea cycle, which is responsible for maintaining sub-toxic levels of ammonia. The final section covers the changes to mitochondrial amino acid metabolism that occur under different pathological conditions. In this case three examples have been chosen comprising ischemia-reperfusion in heart, myocardial hypertrophy and the special relationship that exists between glutamine and cancer cells.