Energy coupling to ATP synthesis by the proton-translocating ATPase
Willams suggests that there was no energy-rich intermediate, butprotons served to deliver energy from respiration chain enzymesand photosynthetic proteins to ATP synthase.
The continual synthesis of ATP ..
The 5-Phosphoribosyl--pyrophosphate (PRPP) formedin the first step is also a precursor of pyrimidine synthesis, and it is also aprecursor of the synthesis of Trp and His. Because it is part of so manyimportant pathways, it is highly regulated. The role of ATP in this step isdifferent from that of the other steps in this pathway in which it is found. ATPactivates the ribose-5-phosphate by adding a pyrophosphate group (PPi)to C1 of the sugar (i.e., there is a group transfer). All of the otherATP-involving steps that follow harness the energy of hydrolysis of a phosphatebond of ATP (exergonic) to drive an endergonic reaction. In these steps, one cantalk about "coupling" of two reactions, such that the exergonic onedrives the endergonic one with the result that the overall G'is negative.
Photosynthetic organisms use energy from sunlight to synthesize their own fuels. They can convert harvested sunlight into chemical energy (including ATP) to then drive the synthesis of carbohydrates from carbon dioxide and water. When they synthesize the carbohydrates, oxygen gets released. Globally, more than 10 billion tons of carbon is "fixed" by plants every year - this means that carbon molecules are converted from being part of a simple gas (carbon dioxide) into more complex, reduced molecules (carbohydrates), making carbon available as food for non-photosynthesizers (and of course, providing oxygen). They use some of the carbohydrate for their own growth and reproduction. It is pretty remarkable when you think about it - have you been to Sequoia National Park or seen the redwoods along our northwest coast? Massive trees, right? Think about the fact that most of that mass is in the form of carbon that was pulled out of the air as carbon dioxide!
examples of endergonic and exergonic reactions - …
The oxidation of NADH and FADH2 by molecular oxygen is coupled in mitochondria to the endergonic synthesis of ATP from ADP and Pi. For many years the nature of the common intermediate between electron transport and ATP synthesis was elusive. Peter Mitchell, who received a Nobel Prize in chemistry in 1978 for his extraordinary insights, suggested that this common intermediate was the proton electrochemical potential. He proposed in the early 1960s that electron transport through the mitochondrial chain is obligatorily linked to the movement of protons across the inner membrane of the mitochondrion. In this way, part of the energy liberated by oxidative electron transfer is conserved in the form of the proton electrochemical potential. This potential, A^H+, is the sum of contributions from the activity gradient and that of the electrical gradient:
the step in ATP synthesis which requires energy is ..
Hydrolysis of ATP
Applications of ATP
ADP + Pi + Energy → ATP
electron transport chain
The change in Gibbs free energy in the reaction is used to assess the energy yield of such reactions, and as a general indicator of the spontaneity of reactions.
[Redox regulation in ATP synthesis]. - National Center …
IMP is also subject to regulation at points after its production. AMP and GMPeach competitively inhibit their own production. Also, each AMP synthesizedrequires one GTP and each GMP synthesized requires one ATP, in a reciprocalfashion as mentioned above. As about equal amounts of AMP and GMP are needed innucleic acid synthesis, this reciprocity provides for that. The rate ofproduction of AMP increases with increasing concentrations of GTP, and that ofGMP with increasing concentrations of ATP.
[Redox regulation in ATP synthesis]
The ATP molecule formed is released when the Gamma subunit makes one 360 degrees turn and once again opens the site.
Synthesis of ATP
Through this mechanism, using the driving force of protonic ions, the enzyme rapidly catalyzes the synthesis of ATP fro ADP and Pi, hence lowering the Ea by using less energy.