Ornithine

• (S) - ( ) -ornithine
• (S ) - ( ) -2,5- diaminopentanoic acid
• L-( )- diaminovaleric
• Abbreviation: Orn

A05BA50

Colorless crystals

Fixed

140 ° C

Readily soluble in water with an alkaline reaction

Template: Infobox chemical / molecular formula search available

Ornithine (from Greek ornis, bird) is a basic, non-proteinogenic α -amino acid. It enters into the L-shape mainly in the urea cycle, as a carrier substance.

Production

L- ornithine was first manufactured by Jaffé 1877 from chicken excrement. The industrial production of L-ornithine is made by hydrolysis of L -arginine in alkaline medium.

Role in the urea cycle

L-ornithine in the urea cycle is formed by catalysis of L-arginine through arginase in water incorporation and release of urea (NH2 -CO- NH2).

L-Ornithine is combined then catalyzed by the ornithine carbamoyl transferase, carbamoyl with the phosphate being split off, and thus forming the L- citrulline.

The argininosuccinate synthetase then catalyzes ATP-consuming condensation with L- aspartic acid. The result is arginine succinate, which is present under physiological conditions as a argininosuccinate, the anion.

L- argininosuccinate is cleaved by the L- argininosuccinate lyase in fumarate and L- arginine. L- arginine can again release urea. This is again present L- ornithine and the reaction circle.

Applications

Ornithine plays a role in the MIO- test in the microbiology. Research has shown that athletic performance in combination with ornithine and arginine can affect the production of growth hormones. A reaction with ornithine can be recognized by the coloration of the agar in the tube:

• Positive reaction: tube remains stained purple
• Negative reaction: Tube showing yellow staining

Isomerism

L- ornithine -configuration at the stereogenic center ( α - carbon atom ) is (S ). Enantiomer for L- ornithine is not found in nature occurring D - ornithine. That is - configured (R ) and only of minor importance.