Amino Acid Metabolism Overview

The process of building proteins from individual amino acids.

A process where certain microorganisms convert nitrogen gas from the atmosphere into ammonia, which is usable by other organisms.

The primary source of carbon atoms for the synthesis of various amino acids.

An amino acid that serves as a crucial nitrogen donor for the synthesis of a wide range of other amino acids.

A small protein that attaches to proteins targeted for degradation, marking them for breakdown.

The process of breaking down proteins within cells and rebuilding them, constantly adjusting to the body's needs.

The basic building blocks used to create proteins and other nitrogen-containing compounds.

When the body uses excess amino acids as fuel instead of storing them.

A condition caused by severe protein deficiency. It leads to muscle wasting, swelling, and other health problems.

A chemical compound containing nitrogen that is essential for building amino acids and other molecules.

The source of carbon atoms used to build the backbones of amino acids.

The process of breaking down and recycling nitrogen from excess proteins, primarily through the urea cycle.

Amino acids are classified based on their biosynthetic pathways. These pathways are categorized based on the sources of carbon and nitrogen atoms. A significant portion of the nitrogen in the amino acids comes from either glutamate or glutamine.

Essential amino acids are those that the body cannot synthesize and must be obtained from diet.

Nonessential amino acids can be synthesized by the body, though dietary intake is still important.

The number of steps required in biosynthesis determines whether an amino acid is essential or nonessential. Many biosynthetic steps indicate that it's essential. This implies that the enzymes needed for the synthesis of these complex amino acids may have been lost during evolution.

Aspartate, Alanine, and Glutamate are synthesized by adding an amino group to an alpha-keto acid.

Glutamate is synthesized by adding an amino group to alpha-ketoglutarate.

Aspartate and Alanine are synthesized by adding an amino group to oxaloacetate and pyruvate, respectively.

Aminotransferases or transaminases are enzymes that catalyze the interconversion of amino acids and alpha-keto acids. These reactions typically involve pyridoxal phosphate (vitamin B6).

A specific aminotransferase that converts oxaloacetate and glutamate to aspartate and α-ketoglutarate. This is crucial for amino acid biosynthesis and degradation.

A specific aminotransferase that converts pyruvate and glutamate to alanine and α-ketoglutarate. Also essential for amino acid biosynthesis and degradation.

Glutamate serves as a 'gateway' amino acid in many aminotransferase reactions, facilitating the transfer of nitrogen from various amino acids to free ammonia.

Increased levels of AST and ALT in blood can indicate liver damage.

The process of breaking down proteins into their constituent amino acids, either from dietary sources or from cellular proteins.

Amino acids derived from the diet or protein breakdown that are not immediately used are degraded and their nitrogen atoms eventually converted to urea for excretion.

An enzyme that activates ubiquitin by attaching it to itself.

An enzyme that transfers ubiquitin from E1 to itself.

An enzyme that attaches ubiquitin to a target protein, marking it for destruction.

A disorder caused by a defect in an E3 protein, leading to the accumulation of proteins and neurological problems.

A chain of 4 or more ubiquitin molecules attached to a protein, signaling its degradation.

Nitrogenase, an enzyme complex, is responsible for nitrogen fixation. It consists of two components: reductase and nitrogenase.

The nitrogenase complex requires a significant amount of energy, using at least 16 ATP molecules to generate two ammonia molecules.

Diazotrophic microorganisms, including bacteria and some archaea, are responsible for the majority of nitrogen fixation on Earth, fixing approximately 10^11 kilograms of nitrogen per year.

Leguminous plants, like beans and peas, form symbiotic relationships with bacteria that fix nitrogen. These bacteria live in root nodules, specialized structures on the plant roots.

Leghemoglobin, a protein similar to hemoglobin, binds oxygen inside the root nodules, preventing oxygen from inhibiting the nitrogenase enzyme.

Glutamate and glutamine are key amino acids involved in assimilating ammonium into organic compounds. Glutamate dehydrogenase catalyzes reductive amination, adding ammonium to α-ketoglutarate to form glutamate.

Glutamine synthase catalyzes the incorporation of a second ammonium ion into glutamate, forming glutamine. This is called reductive amidation.