Dr. Stalker, so ketones are not protonized in mitochondria and get in blood in COOH form? they change the pH in ionized form by the mechanism, which you explain?
Hey Mate,
You're getting a few topics mixed up here.
Mitochondria produce ATP from Glucose (sugar). The glucose is initially metabolized in the cytoplasm via glycolysis then shipped off to the mitochondria where the glucose (now 2 pyruvate molecules) will undergo the krebs cycle and the Electron Transport Chain to produce ATP. Glycolysis and krebs produce ATP via substrate level phosphortlation whereas the electron transport chain produces ATP via oxidative phosphorylation.
Let's paint a picture here: A person eats a meal, now they have glucose in their bodies. Insulin is released, glucose taken into the cells, and we begin metabolism in the way I mentioend above.
What about a fasting person? Say someone is fasting and they have depleted their stores of glucose (which is stored as glycogen). Now, we have no glucose from food or our stores. The body still needs to produce energy, so we urn to ketone bodies. Ketone bodies do NOT have a -COOH group. These ketone bodies are produced in our liver and then sent into the blood stream. The problem is that the ketones (despite not having a -COOH group) still have acidic properties. Again, from my first post, a carboxylic acid has an acidic hydrogen, but so do other organic functional groups. Ketones have acidic hydrogens and, in the blood, can donate these acidic hydrogen (not form COOH groups because Keystone's do not have COOH groups) and that leads to metabolic ketoacidosis. This condition is where our blood pH drops (becomes more acidic) because of the preasence of ketones in our blood. Glucose, which is normally in our blood, has no acidic properties at all, and does NOT lead tot his condition.
Ok, so back to ketone bodies. These ketone bodies are analogous to acetyl-CoA. We do not secrete acetyl-CoA into our blood, we instead secrete these ketone bodies. These ketone bodies will be taken up by cells and organs and then slightly modified/changed into Acetyl-CoA inside of the cell, and then enter the aerobic metabolism pathway via the Krebs cycle, which requires Acetyl-CoA as a key ingredient.
Acetoacetate is a ketone body and notice that it is produced in the liver. This then leaves the liver and enters our blood stream, where it can donate acidic hydrogens (not form a -COOH group) but from an alpha carbon, leading to a lower pH (more acidic) in the blood.
