Organization of the Mitochondrial Matrix
Heart tissue has a high oxidative capacity due to its high content of mitochondria. In addition it is known that the oxidative capacity of mitochondria is correlated to their cristal content and heart mitochondria are known to contain many closely packed cristae. Measures of the inner membrane content (surface area) of heart mitochondria have been made by a number of groups of electron microscopists using stereomorphology (see 1 for review). Their data indicate that a rat heart mitochondrion contains about 60 µm2 of inner membrane surface area for each µm3 of mitochondrial volume. I have shown that these figures are consistent with an average spacing of cristae within a heart mitochondrion of about 150 A2. One can calculate a diameter of 60 A for a spherical protein molecule with a molecular weight of about 80,000. Therefore, it is readily seen that a theoretical construct of a heart mitochondrion would place almost all of the matrix proteins next to the inner membranes.
KeywordsMitochondrial Matrix Heart Mitochondrion Pyruvate Dehydrogenase Complex Glycerol Ether Carnitine Acetyl Transferase
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