Respiration, cellular regulation

On the basis of these observations, suggest how succinyl-CoA regulates the activity of citrate synthase. (Hint See Fig. 6-29.) Why is succinyl-CoA an appropriate signal for regulation of the citric acid cycle How does the regulation of citrate synthase control the rate of cellular respiration in pig heart tissue ... 

Citrate synthase catalyzes the step at which acetyl-CoA enters the cycle, and thus regulation of this enzyme controls the activity of the cycle, the rate of production of reduced coenzymes, and thus the rate of cellular respiration. 

The Regulation of Cellular Respiration Is Governed Primarily by the Need for ATP... 

Free silver ions are the active components of antimicrobial silvers, and it has been shown that as little as one part per million of elemental silver in solution is an effective antimicrobial. Materials such as polymers, charcoal, and hydrocolloids when formulated with silver not only aid wound management and healing but also regulate its release into the wound environment and surrounding tissues. Silver ions kill micro-organisms by inhibiting cellular respiration and cellular function. " It is known that their mode of action is exerted by binding cysteine residues on the cell walls of yeasts such as C. albicans thereby... 

Figure 17.18 Response of the pyruvate dehydrogenase complex to the energy charge. The pyruvate dehydrogenase complex is regulated to respond to the energy charge of the cell. (A) The complex is inhibited by its immediate products, NADH and acetyl CoA, as well as by the ultimate product of cellular respiration, ATP. (B) The complex is activated by pyruvate and ADP, which inhibit the kinase that phosphorylates PDH.

These often involve regulation of transcription. As mentioned in Chapter 18, Section F,2, many of the effects of NO are a resulf of activation of soluble gua-nylate cyclase (p. 561). In the endothelium other hormones, such as the endothelins (p. 1750), atrial natriuretic factor, and bradykinin (Box 22-D), cooperate in the regulation of NO synthase. Neuronal NO synthase fimctions in the brain in olfaction and in formation of memory. In the peripheral system it mediates penile erection and plays a variety of roles in the enteric nervous system. Neuronal NO synthase is often localized to synaptic regions by binding to tissue-specific proteins. NO may also regulafe cellular respiration by inhibition of cytochrome c oxidase. ... 

Copper is one of a number of metals which are known to be essential because they, like essential amino acids, essential fatty acids and essential cofactors, are required for normal metabolism but are not synthesized de novo. The essentiality of Cu was established by Hart, Steenbock, Waddell and Elvehjem [1] in 1928 when they demonstrated that it was required for the synthesis of haemoglobin. Since that time, Cu has been shown to be required for growth, keratinization, pigmentation, bone formation, reproduction, fertility, development of the central and peripheral nervous systems, cardiac function, cellular respiration, nerve function, extracellular connective tissue formation, and regulation of... 

Amino Add Metabolism and Acid-Base Economy The importance of transamination in regulating cellular respiration by the removal of dibasic C4- and Crketo acids, acting as respiratory catalysts in Szent-Gybrgyi s system of hydrogen transport and in the Krebs cycle, was discussed in the first review on transamination (Braunstein, 24). This aspect of the functions of transamination has since been somewhat one-sidedly emphasized by Martins (131) and by Cohen (59, 61), who tends to disregard the immediate relations of this process to nitrogen metabolism. 

Atkinson, D.E. (1977). In Cellular Energy Metabolism and its Regulation. Academic Press, New York. Babcock, G.T. Wikstrom, M. (1992). Oxygen activation and the conservation of energy in cell respiration. Nature 356, 301-309. 

Iron is an essential micronutrient for all organisms. It is a required element in cytochromes and the Fe-S centers of redox proteins involved in key metabolic processes such as photosynthesis, respiration, and the reduction of nitrate. Given the importance of Fe in these major metabolic enzymes, microorganisms under Fe-deficient conditions reduce their cellular Fe quotas (Fe C content) (Sunda et al., 1991) and have reduced photosynthetic (Raven, 1988 Green et al., 1994) and bacterial growth (Tortell et al., 1996) efficiencies. Thus ecosystem C metabolism is regulated in part by the availability of Fe. 

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