Amino Acids

  • Amino acids are organic compounds that contain amine and carboxyl functional groups, along with a side chain specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen, although other elements are found in the side chains of certain amino acids.
  • There are 20 common amino acids in protein plus one rare one
  • No one single pathway for amino acid metabolism


  • α-Ketoglutaric acid is one of two ketone derivatives of glutaric acid.
  • People use it to make medicine. Alpha-ketoglutarate is used for kidney disease; intestinal and stomach disorders, including bacterial overgrowth; liver problems; cataracts; and recurring yeast infections. It is also used for improving the way kidney patients receiving hemodialysis treatments process protein check


  • is an ɑ-amino acid that is used in the biosynthesis of proteins.
  • It can be synthesized in the human body under normal physiological circumstances, making it a nonessential amino acid. It is encoded by the codons UCU, UCC, UCA, UCG, AGU and AGC.

Cysteine Metabolism

  • Cysteine metabolism refers to the biological pathways that consume or create cysteine. The pathways of different amino acids and other metabolites interweave and overlap to creating complex systems.

Aspartic Acid

  • Aspartic acid, is an α-amino acid that is used in the biosynthesis of proteins. Similar to all other amino acids it contains an amino group and a carboxylic acid.


  • Transamination, a chemical reaction that transfers an amino group to a ketoacid to form new amino acids. This pathway is responsible for the deamination of most amino acids. This is one of the major degradation pathways which convert essential amino acids to non-essential amino acids.


  • Hydrolysis is any chemical reaction in which a molecule of water ruptures one or more chemical bonds. The term is used broadly for substitution, elimination, and fragmentation reactions in which water is the nucleophile.


  • Asparagine (Asn) is a central intermediate in amino acid metabolism and an important form of stored or transported nitrogen (N) in higher plants.


  • Methionine is an essential amino acid in humans. As the substrate for other amino acids such as cysteine and taurine, versatile compounds such as SAM-e, and the important antioxidant glutathione, methionine plays a critical role in the metabolism and health of many species, including humans.


  • Tryptophan is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α-carboxylic acid group, and a side chain indole, making it a non-polar aromatic amino acid. It is essential in humans, meaning the body cannot synthesize it; it must be obtained from the diet.


  • Phenylalanine is an amino acid found in many foods and used by your body to produce proteins and other important molecules. It has been studied for its effects on depression, pain and skin disorders.
  • An essential amino acid and precursor of tyrosine


  • Tyrosine is an amino acid that is naturally produced in the body from another amino acid called phenylalanine. It’s found in many foods, especially in cheese, where it was first discovered.
  • Not essential if PHE present


  • Precursor to dopamine
  • Crosses blood-brain barrier
  • Used to treat Parkinson’s disease


  • Neurotransmitter
  • Inhibits norepinephrine release in blood vessels-acts as vasodilator
  • Reduces insuling production in pancreas
  • Deficiency causes Parkinson’s disease
  • Links to schizopherania and ADHD
  • Dopamine is an organic chemical of the catecholamine and phenethylamine families. It functions both as a hormone and a neurotransmitter, and plays several important roles in the brain and body.


  • Norepinephrine, also called noradrenaline, substance that is released predominantly from the ends of sympathetic nerve fibres and that acts to increase the force of skeletal muscle contraction and the rate and force of contraction of the heart.
  • Hormone and neurotransmitter
  • Works through noradrenergic receptors
  • Fight or flight response
  • Increases heart rate and blood pressure


  • Epinephrine, also known as adrenaline, is a medication and hormone. As a medication, it is used to treat a number of conditions, including anaphylaxis, cardiac arrest, and superficial bleeding. Inhaled epinephrine may be used to improve the symptoms of croup.
  • Hormone
  • Actions similar to norepinephrine
  • Fight or Flight response
  • Increases heart rate and blood pressure


  • Tyrosinemia is a genetic disorder characterized by disruptions in the multistep process that breaks down the amino acid tyrosine, a building block of most proteins. If untreated, tyrosine and its byproducts build up in tissues and organs, which can lead to serious health problems.


  • Alanine is a glucogenic amino acid that constitutes a high percentage of the amino acids in most proteins. Also, other amino acids, in particular, branched chain amino acids (BCAA), such as valine, leucine, and isoleucine can be converted to alanine.


  • Leucine is an essential amino acid that is used in the biosynthesis of proteins. Leucine is an α-amino acid, meaning it contains an α-amino group, an α-carboxylic acid group, and a side chain isobutyl group, making it a non-polar aliphatic amino acid.


  • Valine is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group, an α-carboxylic acid group, and a side chain isopropyl group, making it a non-polar aliphatic amino acid. It is essential in humans, meaning the body cannot synthesize it: it must be obtained from the diet.


  • Isoleucine is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group, an α-carboxylic acid group, and a hydrocarbon side chain with a branch. It is classified as a non-polar, uncharged, branched-chain, aliphatic amino acid.


  • Histidine is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group, a carboxylic acid group, and an imidazole side chain, classifying it as a positively charged amino acid at physiological pH.


  • Broken down to glycolysis / gluconeogenesis intermediates
  • A glucogenic amino acid is an amino acid that can be converted into glucose through gluconeogenesis. This is in contrast to the ketogenic amino acids, which are converted into ketone bodies.


  • Broken down to acetyl –CoA
  • A ketogenic amino acid is an amino acid that can be degraded directly into acetyl-CoA, which is the precursor of ketone bodies and “myelin, especially during early development, when brain myelin synthesis is extremely high” according to the National institute of Health.


  • Alcaptonuria is a hereditary metabolic disease in which the individual is lacking in a system, presumably enzymatic, required to break down homogentisic acid.

Methylmalonic Acidemia

  • Methylmalonic acidemia is a disorder in which the body cannot break down certain proteins and fats. The result is a buildup of a substance called methylmalonic acid in the blood. This condition is passed down through families. It is one of several conditions called an “inborn error of metabolism.

Maple Syrup Urine Disease

  • Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disorder affecting branched-chain amino acids. It is one type of organic acidemia. The condition gets its name from the distinctive sweet odor of affected infants’ urine, particularly prior to diagnosis, and during times of acute illness.


  • Homocystinuria is a disorder of methionine metabolism, leading to an abnormal accumulation of homocysteine and its metabolites (homocystine, homocysteine-cysteine complex, and others) in blood and urine.


  • Argininemia, is an autosomal recessive urea cycle disorder where a deficiency of the enzyme arginase causes a buildup of arginine and ammonia in the blood.


  • Hypermethioninemia is an excess of a particular protein building block (amino acid), called methionine, in the blood. This condition can occur when methionine is not broken down (metabolized) properly in the body.

Glycine Encephalopathy

  • Glycine encephalopathy is a rare autosomal recessive disorder of glycine metabolism. After phenylketonuria, glycine encephalopathy is the second most common disorder of amino acid metabolism. The disease is caused by defects in the glycine cleavage system, an enzyme responsible for glycine catabolism.

Propionic Acidemia

  • Propionic Acidemia is a rare metabolic disorder characterized by deficiency of propionyl CoA carboxylase, an enzyme involved in the breakdown (catabolism) of the chemical “building blocks” (amino acids) of certain proteins.


  • Hyperprolinemia is a condition which occurs when the amino acid proline is not broken down properly by the enzymes proline oxidase or pyrroline-5-carboxylate dehydrogenase, causing a buildup of proline in the body.


  • Nitrogen is a nonmetal chemical element. The atmosphere contains more than 78 percent of nitrogen. It has the chemical symbol N and atomic number 7. Its stable inside typically contains 14 nucleons (7 protons and 7 neutrons). It has 5 electrons in its outer shell.


  • In neuroscience, glutamate refers to the anion of glutamic acid in its role as a neurotransmitter: a chemical that nerve cells use to send signals to other cells. It is by a wide margin the most abundant excitatory neurotransmitter in the vertebrate nervous system.

Urea Cycle

  • The urea cycle is a cycle of biochemical reactions that produces urea (NH₂)₂CO from ammonia. This cycle occurs in ureotelic organisms. The urea cycle converts highly toxic ammonia to urea for excretion.

Carbamoyl Phosphate Synthetase

  • Carbamoyl-phosphate synthetase catalyzes the production of carbamoyl phosphate through a reaction mechanism requiring one molecule of bicarbonate, two molecules of MgATP, and one molecule of glutamine. The enzyme from Escherichia coli is composed of two polypeptide chains.


  • The organic compound citrulline is an α-amino acid. Its name is derived from citrullus, the Latin word for watermelon, from which it was first isolated in 1914 by Koga and Odake. It was finally identified by Wada in 1930. It has the formula H₂NCNH(CH₂)₃CHCO₂H.

Ornithine Transcarbamylase

  • Ornithine transcarbamylase is an enzyme that catalyzes the reaction between carbamoyl phosphate and ornithine to form citrulline and phosphate. There are two classes of OTC anabolic and catabolic. Anabolic OTC facilitates the sixth step in the biosynthesis of the amino acid arginine in prokaryotes.

Argininosuccinate Synthetase

  • Argininosuccinate synthase or synthetase is an enzyme that catalyzes the synthesis of argininosuccinate from citrulline and aspartate. In humans, argininosuccinate synthase is encoded by the ASS gene located on chromosome 9


  • Arginase is a manganese-containing enzyme. The reaction catalyzed by this enzyme is: arginine + H₂O → ornithine + urea. It is the final enzyme of the urea cycle. It is ubiquitous to all domains of life.


  • Nitrite. Nitrite is a byproduct of ammonia oxidation produced by the nitrifying bacteria generically known as Nitrosomonas, but in the aquarium, other genera might also be responsible. Nitrite is colorless and odorless, and may result in signs of toxicity at a level as low as 0.10 mg/liter in freshwater.
  • It oxidize hemoglobin’s iron from ferrous to ferric state- unable to carry oxygen- can be serious


  • Nitrosamines produced by reaction of nitrites and secondary amines, such as proline
  • Strong acids or high temperatures of frying favor production
  • Found in the processed meats, beer, cigarette smoke, chewing tobacco
  • Formation inhibited by vitamin C


  • Heme or haem is a coordination complex “consisting of an iron ion coordinated to a porphyrin acting as a tetradentate ligand, and to one or two axial ligands.” The definition is loose, and many depictions omit the axial ligands.


  • Porphyria is a group of diseases in which substances called porphyrins build up, negatively affecting the skin or nervous system. The types that affect the nervous system are also known as acute porphyria, as symptoms are rapid in onset and last a short time.


  • Iron is a chemical element with symbol Fe and atomic number 26. It is a metal, that belongs to the first transition series and group 8 of the periodic table.


  • Transferrins are iron-binding blood plasma glycoproteins that control the level of free iron in biological fluids. Human transferrin is encoded by the TF gene. Transferrin glycoproteins bind iron tightly, but reversibly.


  • Hemoglobin is the protein molecule in red blood cells that carries oxygen from the lungs to the body’s tissues and returns carbon dioxide from the tissues back to the lungs. Hemoglobin is made up of four protein molecules (globulin chains) that are connected together.


  • Myoglobin is an iron- and oxygen-binding protein found in the muscle tissue of vertebrates in general and in almost all mammals. It is distantly related to hemoglobin which is the iron- and oxygen-binding protein in blood, specifically in the red blood cells.

Bohr effect

  • The Bohr effect is a physiological phenomenon first described in 1904 by the Danish physiologist Christian Bohr: hemoglobin’s oxygen binding affinity is inversely related both to acidity and to the concentration of carbon dioxide.

2,3 BPG

  • 2,3-Bisphosphoglyceric acid, also known as 2,3-diphosphoglyceric acid, is a three-carbon isomer of the glycolytic intermediate 1,3-bisphosphoglyceric acid.

Sickle Cell Anemia

  • Sickle cell anemia is a genetic disease affecting hemoglobin
  • Sickle cell anemia is an inherited form of anemia — a condition in which there aren’t enough healthy red blood cells to carry adequate oxygen throughout your body. Normally, your red blood cells are flexible and round, moving easily through your blood vessels.


  • Bilirubin is a yellow compound that occurs in the normal catabolic pathway that breaks down heme in vertebrates. This catabolism is a necessary process in the body’s clearance of waste products that arise from the destruction of aged or abnormal red blood cells.

Biliverdin Reductase

  • Biliverdin reductase is an enzyme found in all tissues under normal conditions, but especially in reticulo-macrophages of the liver and spleen. BVR facilitates the conversion of biliverdin to bilirubin via the reduction of a double-bond between the second and third pyrrole ring into a single-bond.

Enterohepatic Circulation

  • Enterohepatic circulation refers to the circulation of biliary acids, bilirubin, drugs or other substances from the liver to the bile, followed by entry into the small intestine, absorption by the enterocyte and transport back to the liver.