What Is Threonine?
Threonine, an essential amino acid with the chemical formula C4H9NO3, features a hydroxyethyl group in its side chain. It is represented by the abbreviations Thr or T and has the CAS number 80-68-2 for its L-isomer (72-19-5 for L-threonine). With two optically active centers, threonine exists in four isomers: L-threonine (2S,3R), D-threonine (2R,3S), L-allothreonine (2S,3S), and D-allothreonine (2R,3R).
Uses of Threonine
Threonine is primarily used as a pharmaceutical ingredient, in culture media, and as a food additive. The L-isomer of threonine, the only form present in vivo, is essential for humans and animals as it cannot be synthesized by the body. It is reputed to support growth and metabolism, enhance liver function, alleviate gastritis, and reduce muscle hypertonia. Furthermore, it helps prevent fatty liver disease by inhibiting fat accumulation in the liver. Threonine is found in high concentrations in animal proteins, especially in eggs, skim milk, and gelatin.
Properties of Threonine
Threonine is a white powder at room temperature, with a molecular weight of 119.12 and a melting point of 244°C. It is slightly soluble in water and nearly insoluble in ethanol and diethyl ether, odorless, with a density of 1.07 g/mL. The acid dissociation constants (pKa) are 2.63 for the carboxyl group and 10.43 for the amino group.
Types of Threonine
Threonine is available as reagent products for R&D, feed-use amino acids, and food additives, with only the L-isomer utilized in feed and food applications. Reagent products offer a mix of DL, D, and L-isomers.
1. Reagent Products for Research and Development
These include DL mixture, D-body, and L-body threonine, available in various sizes such as 0.5g to 500g, suitable for laboratory use and can be stored at room temperature.
2. Feed-Use Amino Acids
L-threonine is exclusively used in animal feed, benefiting fattening pigs and broilers, typically supplied in 25 kg bags.
3. Food Additive
As a food additive, threonine is utilized in seasonings and as a nutrient enhancer, available in bulk quantities like 25 kg and 50 kg for commercial use.
Other Information on Threonine
1. Reactivity of Threonine
Stable under usual conditions, threonine’s reactivity can be affected by light, requiring storage away from heat and sunlight. It reacts with strong oxidizers, and hazardous decomposition products include carbon monoxide, carbon dioxide, and nitrogen oxides.
2. Biosynthesis of Threonine
Biosynthesis in plants and microorganisms involves several steps, including phosphorylation, reduction, and hydroxylation reactions, culminating in the production of threonine.
3. Precautions for Handling Threonine
Appropriate safety measures, including local exhaust ventilation and protective gear, are essential when handling threonine. It should be stored in a cool, ventilated area in a light-shielded, sealed container.