Molecular structure of mitochondrial cristae, solid state biochemistry and a simple theory of respiration-phosphorylation coupling.
Thanks to the improvement of preparatory procedures in electron microscopy during the 1960's the structural analysis of mitochondria has been extended to the molecular level leading to an almost 40-year-old misconception regarding mitochondrial structure being replaced by a more realistic version of the structure. The following observations are reviewed: 1) There are three different types of membranes in the mitochondria. 2) Geometrically regularly distributed circumscribed respiratory chain domains are surrounded by a continuous tricarboxylic acid cycle domain. 3) The cristae are compact structure with the enzyme molecules in a three-dimensional arrangement. 4) The active sites of most enzyme molecules are buried in the cristae and are exposed to an environment characterized as a biological solid state. 5) A water translocating mechanism removes water from the cristae maintaining a low water activity in the cristae. 6) The cristae are connected to the cytosol directly through proteinaceous pathways extending through the two surface membranes. 7) The matrix communicates with the cytosol by a route through the two surface membranes, bypassing the cristae. 8) The permeability of the inner surface membrane changes with the respiratory state. 9) The inner membrane particles can be made to appear under experimental conditions that prove their appearance to be an artifact. 10) A simple theory of respiration-phosphorylation coupling is proposed based on the solid state of the cristae. The theory agrees with the chemiosmotic theory with respect to the involvement of proton movement as basis for energy transduction, but differs with respect to how protons contribute to transduction.
Sjöstrand
F S
FS
Department of Biology, University of California, Los Angeles.
D000818:Animals; D006801:Humans; D008854:Microscopy, Electron; D008928:Mitochondria / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure*; D015394:Molecular Structure; D010085:Oxidative Phosphorylation; D013329:Structure-Activity Relationship