Which mechanism is the most efficient at moving NADH equivalents from the cytoplasm into the mitochondria?
A) citrate shuttle
B) malate-aspartate shuttle
C) glyoxylate shunt
D) glycerol phosphate shuttle

Question

Quizplus · Accepted Answer

The malate-aspartate shuttle is the most efficient at moving NADH equivalents from the cytoplasm into the mitochondria. This shuttle uses the enzyme malate dehydrogenase to convert cytoplasmic oxaloacetate and NADH to malate and NAD+. Malate is then transported into the mitochondria where it is oxidized by mitochondrial malate dehydrogenase to reform oxaloacetate, with the concomitant reduction of mitochondrial NAD+ to NADH. The mitochondrial oxaloacetate is then converted to aspartate, which is transported back into the cytoplasm and converted back to oxaloacetate, with the concomitant oxidation of cytoplasmic NADH to NAD+. Because this shuttle does not involve any net loss of energy or reduction potential, it is the most efficient at transferring NADH equivalents into the mitochondria.

Which Mechanism Is the Most Efficient at Moving NADH Equivalents