Electron Transport and Oxidative Phosphorylation
Formation of submitochondrial particles. These resealed inside-out inner membrane vesicles are formed when
mitochondria are subjected to a variety of disruptive forces; they can support both reducing-equivalent transport and
phosphorylation of ADP. Removal of the inner membrane spheres from the vesicles leads to the loss of ability to
is due to pore-like structures that consist of a protein (M.W.
30,000) embedded in the phospholipid bilayer.
dition of the purified pore protein renders phospholipid bi-
layers permeable to a variety of substances. An analogous
pore protein, known as porin, has been identified in the
outer membrane of gram-negative bacteria (Chapter 11).
The matrix is viscous and contains all TCA cycle en-
zymes except succinate dehydrogenase, which is a compo-
nent of electron transport complex II and is located within
the inner membrane. Enzymes of the matrix or the in-
ner mitochondrial membrane mediate reactions of fatty
acid oxidation, ketone body formation and oxidation, and
biosynthesis of urea, heme, pyrimidines, DNA, RNA, and
protein. Mitochondria are involved in programmed cell
death apoptosis, (see Chapter 26).
The structure, mechanism of replication of mitochon-
drial DNA, and processes of transcription and translation
are unique in several respects (discussed later).