Threonine is an amino acid. Amino acids are the building blocks the body uses to make proteins. Threonine is used to treat various nervous system disorders including spinal spasticity, multiple sclerosis, familial spastic paraparesis, and amyotrophic lateral sclerosis (ALS, Lou Gehrig’s disease).

Just a recap, if you have on the end a Hydroxyl group, so OH. You have an Amino group, like an NH2, or you have a Sulfhydryl group, like an SH group on the end, then that would tell you that you have a polar R-Group for that particular Amino acid.

The amino group consists of a nitrogen atom attached by single bonds to hydrogen atoms. An organic compound that contains an amino group is called an amine. Like oxygen, nitrogen is also more electronegative than both carbon and hydrogen, which results in the amino group displaying some polar character.

Threonine exhibits good solubility in water and is hardly soluble in ethanol.

Histidine

Nonessential amino acids include: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine. Conditional amino acids are usually not essential, except in times of illness and stress.

Amino groups are composed of a N atom bonded to two H atoms. Amino groups can act as a base because they can pick up an H+ from a solution. Amino groups can be ionized with a 1+ charge under basic condition. Amines can readily form hydrogen bonds.

An amino acid has this ability because at a certain pH value (different for each amino acid) nearly all the amino acid molecules exist as zwitterions. If acid is added to a solution containing the zwitterion, the carboxylate group captures a hydrogen (H+) ion, and the amino acid becomes positively charged.

There are three amino acids that have basic side chains at neutral pH. These are arginine (Arg), lysine (Lys), and histidine (His). Their side chains contain nitrogen and resemble ammonia, which is a base. Their pKa’s are high enough that they tend to bind protons, gaining a positive charge in the process.

If there are more positively charged hydroniums than negatively charged hydroxyls, then the substance is acidic. If there are more negatively charged hydroxyls than positively charged hydroniums, then the substance becomes basic.

disulfide bond

Two proteins have the same number and type of amino acids but different tertiary structures. This can result in ionic, hydrogen and disulphide bonds to form in different locations in each protein. Such differences may cause variations in the three dimensional structures of the proteins (tertiary structure).

When a protein is denatured, secondary and tertiary structures are altered but the peptide bonds of the primary structure between the amino acids are left intact. Since all structural levels of the protein determine its function, the protein can no longer perform its function once it has been denatured.