Mitochondrial structures, changes

The incubation of Uver homogenate with CNT for 4 h at 0°C leads to considerable decrease of mitochondrial activity (perhaps due to inhibition of chain transfer of electrons in mitochondria). The data obtained showed (Fig. 2.1b) that the cytotoxicity caused by CNT is associated with not only structural changes in the cell membrane, but also with CNT influence on their functional properties. 

We see that electron transfer can be accompanied by loss of a proton and that E ° may become pH dependent. (See also Eq. 16-18.) Even with cytochrome c, although there is little structural change upon electron transfer, there is an increased structural mobility in the oxidized form.156 This may be important for coupling and could also facilitate associated proton-transfer reactions. For example, it is possible that in some cytochromes the imidazole ring in the fifth coordination position may become deprotonated upon oxidation. This possibility is of special interest because cytochromes are components of proton pumps in mitochondrial membranes (Chapter 18). 

R Boyer, Concepts in Biochemistry (1999), Brooks/Cole (Pacific Grove, CA), pp 480-495 An introduction to mitochondrial structure and function R Capaldi, Trends Biocbem. Sci. 25, 212-214 (2000) The Changing Face of Mito chondnal Research ... 

Changes in mitochondrial structure are very relevant during X-ray induced apoptosis. A few hours after irradiation, a hyperpolarisation of A /m is noticed. This likely represents the attempt to restore the depleted ATP levels, stimulating the oxidative burst of surviving mitochondria. If this secondary oxidative stress overcomes the threshold given by mitochondrial thiols, mitochondrial cardiolipin is oxidized and mitochondrial inner membrane allows the leakage of A /m with the consequent initiation of the execution phase. 

Golding C, Senior S, Wilson MT, O Shea P. Time resolution of binding and membrane insertion of a mitochondrial signal peptide correlation with structural changes and evidence for cooperativity. Biochemistry. 1996 20 10931-10937. 

Since mitochondrial morphology remains intact throughout apoptosis, until recently, mitochondria were not assumed to be critical players in the effecter phase of apoptosis. But accumulating evidence indicates that mitochondria exhibit major functional roles and structural changes that serve to regulate apoptosis. Data from diverse models systems conclude that (1) collapse of mitochondrial inner transmembrane potential (A Pm), (2) mitochondrial... 

Changes in mitochondrial structures, caused by freezing or frozen storage of muscle (41,42) or liver tissue (43), also can be demonstrated by electron microscopy. Such structural changes increase progressively with increases in cooling rate (39). 

Ultrastructural changes of proximal tubular cells occur as early as 1 hour after cephaloridine administration to rabbits and are characterized by loss of brush border, less elongated mitochondria and disappearance of structures associated with endocytosis. Later ultra-structural changes include disorganization of lateral interdigitations of plasma cell membrane and mitochondrial swelling [28,29]. 

See also Standard Reduction Potential, Mitochondrial Structure and Function, Free Energy Changes from Oxidation/Reduction, Electron Transport, NAD+, NADH... 

Beilke, D., R. Weiss, F. Lohr, P. Pristovsek, F. Ffannemann, R. Bernhardt et al. (2002). A new electron transport mechanism in mitochondrial steroid hydroxylase systems based on structural changes upon the reduction of adrenodoxin. Biochemistry 41, 7969-7978. 

A review of the basic concepts of metabolism in Chapter 14 and mitochondrial structure, redox potentials, the proton-motive force, and free-energy changes in Chapter 18 will help you to understand this chapter. 

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