Phosphorylation, coupled effect

Stucki (1980, 1984) applied the linear nonequilibrium thermodynamics theory to oxidative phosphorylation within the practical range of phosphate potentials. The nonvanishing cross-phenomenological coefficients Ly(i v /) reflect the coupling effect. This approach enables one to assess the oxidative phosphorylation with H+pumps as a process driven by respiration by assuming the steady-state transport of ions. A set of representative linear phenomenological relations are given by... 

Mechanistic P/0 ratio Oxidation of reducing equivalents produced during glycolysis and in the TCA cycle takes place in the mitochondria (oxidative phosphorylation). The maximal ATP production rate, coupled with electrons exchanged, is determined by the mechanism of sites III and IV in the electron transport chain. The mechanistic P/0 ratio is equal to the number of moles ATP synthesized by the oxidation of one mole of NAD(P)H+Fr by 0.5 mole O2. The electrochemical potential change in site III of the respiratory chain is 41.4 kJ per mole NAD(P)FI+H oxidized and 99.6 kJ moP for the site IV, whereas the standard energy of ADP phosphorylation to ATP is 30.5 kJ moP. Thus, a maximum of 1 mole of ATP can be produced in site III per mol NAD(P)H+H oxidized, and a maximum of 2 moles ATP in site IV, leading to a maximal mechanistic P/O ratio of 3. However, it is not demonstrated that the mechanistic P/0 ratio of oxidative phosphorylation is effectively 3 due to the inefficiency of sites III and IV. 

Solvent effects on the magnitude of spin-spin coupling constants in phosphoryl compounds have been reported, as have the solvent effects on the relative strengths of phosphoric acid and some of its partially esterified derivatives.The variation of i.r. frequencies of (122) and (123)... 

A major way to control enzyme activity is the reversible phosphorylation of serine or threonine residues. It s such a major way to regulate enzymes that you will spend much of your time trying to remember whether or not enzyme X is activated or inactivated by phosphorylation, and you will invariably forget one or two of them on the exam. By remembering a couple of generalities,2 you can actually figure out a lot of the effects of phosphorylation on specific enzymes without really memorizing them. 

Chronic opiate treatment results in complex adaptations in opioid receptor signaling. Much has been learned from studies on mechanisms of tolerance to the analgesic effects of opiates. This is a major clinical problem, as it means that ever-escalating doses are required for the treatment of chronic pain. The classic view was that tolerance reflects a decrease in functional opioid receptors via desensitization and internalization. Desensitization occurs when receptors are uncoupled from G proteins as a result of phosphorylation by G-protein-coupled receptor... 

Francesconi, A. and Duvoisin, R. (2000) Opposing effects of protein kinase C and protein kinase A on metabotropic glutamate receptor signaling selective desensitization of the inositol trisphosphate/Ca2+ pathway by phosphorylation of the receptor-G protein-coupling domain. Proc. Natl. Acad. Sci. USA 97,6185-6190. 

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