Biochemistry: Amino Acid Metabolism

The pool of free amino acids in the body, maintained by a constant balance between the synthesis and breakdown of proteins.

The process of breaking down dietary proteins into smaller peptides and amino acids for absorption.

The enzyme pepsin, secreted by the stomach, breaks down proteins into smaller peptides.

The conversion of an amino acid's amino group (NH2) to a keto group (C=O).

Removal of the amino group (NH2) from an amino acid, generating ammonia (NH3).

The primary nitrogenous waste product excreted by mammals, created in the liver from ammonia.

The process of breaking down proteins and other nitrogen-containing molecules in the body, releasing amino acids into the amino acid pool.

Amino acids that the body can synthesize from other molecules. They are not essential in the diet.

An enzyme that catalyzes the transfer of an amino group from an amino acid to an α-keto acid.

A coenzyme crucial for aminotransferases. It's a derivative of vitamin B6.

A specific aminotransferase that functions in the direction of glutamate synthesis during amino acid breakdown.

A specific aminotransferase that transfers amino groups from glutamate to oxaloacetate, forming aspartate during amino acid catabolism.

The removal of an amino group from an amino acid. The amino group is released as ammonia (NH3).

A key intermediate in amino acid metabolism. It can receive amino groups from other amino acids during transamination.

A nitrogenous waste product produced during amino acid breakdown. It is a primary source of nitrogen for urea synthesis in the liver.

The synthesis of nonessential amino acids from common metabolic intermediates like pyruvate, oxaloacetate, α-ketoglutarate, and 3-phosphoglycerate.

The conversion of 3-phosphoglycerate to serine, a nonessential amino acid, through transamination.

The process of incorporating an amino group (NH2) into a molecule to create an amino acid.

Hydrochloric acid (HCl) plays a crucial role in protein digestion by killing certain bacteria and denaturing proteins, making them easier to break down by proteases.

Pepsin, an endopeptidase, is secreted as an inactive form called pepsinogen. It is activated by HCl or other pepsin molecules, breaking down dietary proteins into peptides and amino acids.

Pancreatic proteases further break down large polypeptides produced in the stomach into oligopeptides and amino acids. They have different specificities for amino acid R-groups.

Aminopeptidase, an exopeptidase found on the intestinal surface, cleaves amino acids from the N-terminal end of oligopeptides, producing smaller peptides and free amino acids.

Nitrogen removal from amino acids is crucial for energy production and occurs in a series of steps. This involves removing the amino group, transporting it to the liver, and processing it for excretion as urea.

Transamination is a process where an amino group from an amino acid is transferred to a keto acid, using an aminotransferase enzyme and pyridoxal phosphate (PLP).

Oxidative deamination is a step in amino acid catabolism where the amino group is removed as ammonia. This is catalyzed by specific enzymes and involves the oxidation of the α-carbon.

The urea cycle is a metabolic process occurring in the liver that converts ammonia into urea, the main form of nitrogen excretion in mammals. This cycle involves multiple steps and enzymes.

The process of removing the amino group from glutamate, releasing free ammonia (NH3) and generating α-ketoglutarate. It's a key step in amino acid catabolism, particularly in the liver and kidney.

An important intermediate in the TCA cycle, α-ketoglutarate participates in amino acid catabolism by accepting the amino group removed from glutamate during oxidative deamination.

The enzyme responsible for oxidative deamination of glutamate. It can use either NAD+ or NADP+ as a coenzyme.

The process of removing the amino group from glutamate to form α-ketoglutarate is regulated by various factors including energy levels. GTP inhibits, while ADP activates the enzyme, signifying the need for energy production.

The process of removing the amino group from glutamate to form α-ketoglutarate is regulated by various factors including energy levels. GTP inhibits, while ADP activates the enzyme, signifying the need for energy production.

The liver plays a crucial role in amino acid catabolism by converting ammonia (NH3) into urea. This process is particularly important in the removal of nitrogenous waste from the body.

The urea cycle is a series of biochemical reactions that convert ammonia (NH3) into urea for excretion. It's a key pathway for nitrogen removal in the body and is primarily carried out in the liver.

Urea, a waste product of nitrogen metabolism, is produced in the liver and transported via blood to the kidneys for excretion in urine.

The first committed step in the urea cycle, where carbamoyl phosphate is synthesized from ammonia and bicarbonate.

The enzyme responsible for catalyzing the condensation of ammonia and bicarbonate into carbamoyl phosphate in the urea cycle.

The reaction in the urea cycle where ornithine, an amino acid, is converted to citrulline by accepting the carbamoyl group.

The enzyme that catalyzes the transfer of the carbamoyl group from carbamoyl phosphate to ornithine, producing citrulline.

The process in the urea cycle where the second nitrogen atom is incorporated into argininosuccinate, generating a molecule with two nitrogens.

The reaction in the urea cycle where argininosuccinate is cleaved into fumarate and arginine, releasing fumarate as a by-product.

The final step in the urea cycle, where arginine is hydrolyzed by arginase into ornithine and urea, releasing urea as the final product.