Some requirements for pyruvate oxidation by plant mitochondrial preparations.

coenzyme A becomes progressively less under these conditions. As previous authors have pointed out (e.g. Laties, 1953b; Lindberg & Ernster, 1954) such a result might be expected if a single dehydrogenase well supplied with substrate was sufficiently active to saturate an electron-transfer system normally shared by subsequent dehydrogenation steps. In conclusion it may be mentioned that responses to coenzyme A and cocarboxylase may be expected when other preparations are investigated, although the high rates of oxygen uptake which have been recorded without benefit of such additions may indicate a degree of self sufficiency which would make these preparations less desirable for such demonstrations. However, we have already been able to show responses to these cofactors in the oxidation of oxaloacetate by preparations from cauliflower and potato.