Amino acids - A glossary of terms

Ion Exchange

As mentioned elsewhere, ion exchange columns are used in amino acid analysis, so what is ion exchange:

Elements, such as sodium are made up of protons and electrons. These are known as ions - protons being positive ions ans electrons being negative ions. Each element is made up of 'rings' of electrons. In each element there are the same amount of protons as electrons to make the charge on the element neutral.
However, if another element is introduced to the other element, an exchange of electrons will occur.

For instance:

Sodium has one electron on its outermost ring but chlorine has seven on its outer ring. If the two elements are introduced to each other, the chlorine element 'wants' another electron to make its outer ring full (eight being the most it can hold) and the sodium element needs tolose an electron to make its outer ring full. So, an 'exchange of ions' occurs.

So, when an amino acid is introduced to the resin, depending on how many electrons it 'has to offer' depends upon how strong the acid 'sticks' to the resin.

Hydrolysis

By protein hydrolysis is meant the 'cleavage' of peptide bonds of a polypeptide or protein.

In acidic hydrolysis (the most common form of hydrolysis), the sample is weighed and transferred to a hydrolysis tube. Boiling hydrochloric acid is the added to the hydrolysis tube.

Any Oxygen dissolved in the liquid should then be removed - to do this connect nitrogen and a vacuum line. The nitrogen should be purged through the pyrogallic acid to remove any ammonia.
The sample should then be frozen at -50degC to -70degC and then evacuate the system. Thaw the sample, carefully, to prevent boiling. After thawing the vacuum line should be closed and nitrogen allowed into the tubes to saturate the sample solution with oxygen free gas.
The tubes should be sealed and placed in an oven at 106degC - 110degC and left for 18 - 144 hours.

This being an example of how hydrolysis is usually performed.

The main Amino Acids

A- Alanine, C- Cysteine, D - Aspartic Acid, E - Glutamic Acid, F - Phenylalanine, G - Glycine, H - Histidine, I - Isoleucine, K - Lysine, L - Leucine, M - Methionine, N - Asparagine, P - Proline, Q - Glutamine, R - Arginine, S - Serine, T - Threonine, V - Valine, W - Tryptophan, Y - Tyrosine

Chocolate

Contains Tyramine - Derived from Tyrosine. Also to be found in Cola and beer. Increases the availability of tryptophan, which is the precursor to serotonin.

The excellent Wikipedia entry on Amino acids