Regarding gluconeogenesis pathway, the process of gluconeogenesis

In animals, acetyl-CoA, produced by the degradation of fatty acids, cannot form pyruvate or oxaloacetate. Although acetyl-CoA both go through the citric acid cycle.

But all are converted to CO2. Therefore, the animal body cannot convert fatty acids into glucose.

And plants, because they have two other enzymes, isocitrate lyase and malate synthase, which can convert acetyl-coa into oxaloacetate. (Glyoxylic acid cycle pathway).

As a result of the B-oxidation of fatty acids, reduced FADH2 and NADH are directly produced, and the acetyl-CoA formed also produces FADH2 and NADH through the citric acid cycle. Through the electron transport chain, ATP is synthesized in large quantities to provide energy. Therefore, the function of fatty acid oxidation is undoubtedly to produce a large amount of energy, but this oxidation does not provide raw materials for gluconeogenesis.

PS: The synthesis of ketone bodies is mainly a function of the liver, where acetyl-CoA can be converted into acetoacetic acid, a certain hydroxybutyric acid and acetone, collectively called ketone bodies, when the acetyl-CoA produced by B-oxidation exceeds the required amount of citric acid cycle, it will go to the road of ketone body synthesis. Although the brain normally uses glucose primarily for energy, it is important to be hungry or diabetic.

In the case, acetoacetic acid is first used as an energy source.

Odd carbon atom fatty acids are mainly found in ruminants.

If pyruvate is not produced, there is no more to write. (Re ps: B in the text is a hundred towers).

Acetyl-CoA, which is produced by the oxidation of fatty acids, is not a raw material for gluconeogenesis.

The process is two-staged:

1. Various gluconeogenesis precursors (except glycerol) are converted into phosphoenolpyruvate;

2. Phosphoenolpyruvate is converted into glucose-6-phosphate and then regenerates various monosaccharides or polysaccharides.

The main precursors of gluconeogenesis are lactic acid, pyruvate, amino acids and glycerol. In the digestive tract of ruminants, a large amount of cellulose can be converted into propionic acid by the action of bacteria, which can also be converted into sugar in the body.

Its functions: 1. The main physiological significance of gluconeogenesis is to ensure the relative constant concentration of blood glucose in the case of starvation.

The normal concentration of blood glucose is that even after fasting for several weeks, the blood glucose concentration can still be maintained around the same level, which is of great significance for ensuring the function of some tissues that rely mainly on glucose for energy, and the daily glucose utilization in normal people who are in a quiet state after fasting overnight (8-10 hours);

The brain is about 125g, the muscle (resting state) is about 50g, the blood cells are about 50g, these tissues alone consume 225g of sugar, the body stores about 150g of available sugar, and the muscle glycogen with the largest sugar storage is only used for its own oxidation and energy, and if only the liver glycogen storage is used to maintain blood sugar concentration for no more than 12 hours, it can be seen that gluconeogenesis is important.

2. Gluconeogenesis is closely related to lactic acid.

During intense exercise, muscle glycolysis produces a large amount of lactic acid, which can be transported to the liver through the blood to resynthesize liver glycogen and glucose, so that muscle glycogen, which cannot directly produce glucose, indirectly becomes blood sugar, and is conducive to the energy in the lactic acid molecule, renews muscle glycogen, and prevent the occurrence of lactic acidosis.

3. Assist in amino acid metabolism.

Experiments have confirmed that glycogen content in the liver increases after protein consumption; In fasting, advanced diabetes mellitus, or excess cortisol, the formation of amino acids into sugar may be the main pathway of amino acid metabolism due to the breakdown of tissue proteins, the increase of plasma amino acids, and the enhancement of glucose.

Most of the gluconeogenesis pathway reactions are the reverse of the enzymatic pathway, catalyzed by the same enzymes.

However, there are 3 steps in the enzyme pathway that are irreversible, and the gluconeogenesis silver-hidden pathway requires different enzymes to bypass the 3 irreversible reactions of the fermentation. These enzymes are:

1 Pyruvate carboxylase.

2 Phosphoenolpyruvate carboxykinase.

3 Fructose diphosphatase.

4 Glucose-6-phosphatase.

Gluconeogenesis: The process of converting from non-tremor sugar substances to glucose is called gluconeogenesis and is the only way for monosaccharide biosynthesis in the body. The process by which a one-way reaction catalyzed by different enzymes causes two substrates to transform each other is called the substrate cycle.

The liver is the main organ of gluconeogenesis, and the renal neogenesis is enhanced during long-term starvation and acidosis.

Its physiological meaning is:

As an important blood sugar supplement** to maintain constant blood sugar levels.

Prevents lactic acidosis.

Assists in amino acid metabolism.

The raw materials of gluconeogenesis mainly include sugar-producing amino acids (sweet, propylene acid, Su, silk, asparagus, grain, cyste, prote, essence, group, etc.), organic acids (lactic acid, pyruvate and various carboxylic acids in the tricarboxylic acid cycle, etc.) and glycerol.

Gluconeogenesis, also known as gluconeogenesis, is the process by which organisms transfer a variety of non-sugar substances into glucose or glycogen.

In mammals, the liver is the main organ of gluconeogenesis, and under normal circumstances, the gluconeogenesis capacity of the kidney is only 1 10 of that of the liver, and the gluconeogenesis capacity of the kidney can be greatly enhanced when starved for a long time. The main precursors of gluconeogenesis are lactic acid, pyruvate, amino acids and glycerol.

1. Any substance that can produce pyruvate can be turned into glucose. For example, the intermediates of the tricarboxylic acid cycle, citric acid, isocitrate, ketoglutarate, succinic acid, fumarate and malic acid can be converted into oxaloacetate and enter the gluconeogenesis pathway.

2. Most amino acids are sugar-producing amino acids such as alanine, glutamic acid, aspartic acid, serine, cysteine, glycine, arginine, histidine, threonine, proline, glutamine, asparagine, methionine, valine, etc., which can be converted into pyruvate, -ketoglutarate, oxaloacetate and other tricarboxylic acid cycle intermediates to participate in the gluconeogenesis pathway.

3. CORI circulation: a large amount of lactic acid produced during strenuous exercise will quickly diffuse to the blood, flow to the liver with the bloodstream, first oxidized into pyruvate, and then converted into glucose through gluconeogenesis, and then replenish blood sugar, and can also be re-synthesized muscle glycogen to be stored. This lactate-glucose cycle is called the Cori cycle or lactate cycle.

4. The anti-stupid gluconeogenesis pathway is very active, and the bacteria in the cow's stomach decompose cellulose into acetic acid, propionic acid, butyric acid and other odd fatty acids, which can be converted into succinyl Coa to participate in the gluconeogenesis pathway to synthesize glucose.

Dr. Tang is a candy or something like that, you can make it yourself.

Gluconeogenesis: Also known as gluconeogenesis. The process of converting from simple non-sugar precursors (lactic acid, glycerol, sugar-producing amino acids, etc.) to sugars (glucose or glycogen).

Gluconeogenesis is not a simple reversal of glycolysis. Although gluconeogenesis initiated by pyruvate takes advantage of the reverse reaction of the seven-step equilibrium reaction in glycolysis, it is necessary to take advantage of the enzymatic reactions that are not present in the other four steps of digestion to bypass the three irreversible reactions in the digestion process. Gluconeogenesis ensures that the body's blood sugar levels are at a normal level.

The main organ of gluconeogenesis is the liver. Under normal circumstances, the ability of the kidney to gluconeogenesis is only one-tenth of that of the liver, but the ability of the kidney to become gluconeogenesis can be greatly enhanced during long-term starvation. The process by which non-sugary substances (such as pyruvate, lactic acid, glycerol, sugar-producing amino acids, etc.) are converted into glucose.

These three steps of the reaction are all strong exothermic reactions, and they are:

1 Glucose is catalyzed by hexokinase to produce glucose-6 phosphate δg= kj mol

2 6 phosphofructose is catalyzed by phosphofructokinase to produce 1,6 bisphosphatefructose δg = kj mol

3 Phosphoenolpyruvate is generated by pyruvate kinase to pyruvate δg= kj mol

This is how these three steps of reaction will be bypassed.

1 Glucose-6 phosphatase catalyzes the production of glucose-6-phosphate.

2 Fructose 1,6 bisphosphatase catalyzes the production of fructose 1,6 bisphosphate to fructose 6 phosphate.

3 This process consists of two reactions, the first of which is catalyzed by pyruvate carboxylase and the coenzyme is biotin, which consumes 1 molecule of ATP. The second reaction is catalyzed by phosphoenolpyruvate carboxokinase, and the reaction consumes 1 molecule of GTP.

Since pyruvate carboxylase is only present in mitochondria, pyruvate in the cytosol must enter the mitochondria in order to carboxylation to oxaloacetate. The phosphoenolpyruvate carboxykinase is present in both the granularium and the cytosol, so oxaloacetate can be directly converted into phosphoenolpyruvate in the microchondria and then into the cytosol, and can also be converted into phosphoenolpyruvate in the cytosol. However, oxaloacetate does not directly permeate mitochondria and is transported into the cytosol in two ways:

One is to reduce it to malic acid through the action of malate dehydrogenase, and then enter the cytosol through the mitochondrial membrane, and then dehydrogenate dehydrogenase in the cytosol will dehydrogenate to oxaloacetate and enter the gluconeogenesis reaction pathway. Another way is to generate aspartic acid through the action of aspartate aminotransferase, and then escape from the mitochondria, and the aspartic acid entering the cytosol is then catalyzed by the aspartate aminotransferase in the cytosol to resume the production of oxaloacetate. Experiments have shown that when pyruvate or certain sugar-producing amino acids that can be converted into pyruvate are used as raw materials for heterogeneous sugar, malic acid is used to carry out gluconeogenesis through mitochondria; When lactic acid undergoes gluconeogenesis reaction, it is often ** chondria to produce oxaloacetic acid, and then converted into aspartic acid and enters the cytosol.

Gluconeogenesis. The pathway is that when the liver or kidney uses pyruvate as a raw material for gluconeogenesis, seven of the reactions in gluconeogenesis are glycolysis.

They have the same enzyme catalysis. But there are three steps in glycolysis, which is an irreversible reaction. These three steps must be bypassed in gluconeogenesis at the cost of more energy expenditure.

These three steps of the reaction are all strong exothermic reactions, and they are slag grip:

1. Glucose.

Glucose-6 phosphate is catalyzed by hexokinase to glucose-6 δg= kj mol.

2. 6 phosphofructose.

Phosphofructokinase catalyzes the generation of 1,6 bisphofructose δg = kj mol.

3. Phosphorus such as zhaoqingic acid enol-pyruvate is generated by pyruvate kinase to acetone guess acid δg= kj mol.