Question

Describe the behavior of a mixture of glutamic acid, arginine, and valine on paper electrophoresis at \(\mathrm{pH} 6.0\).

Short answer

Answer: At pH 6.0, glutamic acid will have a negative charge and will move towards the anode (positive electrode), arginine will have a positive charge and will move towards the cathode (negative electrode), and valine will have a neutral charge, resulting in minimal or no movement during the electrophoresis process.

Step-by-step solution

Understanding paper electrophoresis

Paper electrophoresis is a technique used to separate biological molecules, such as amino acids, based on their charge and size. In this technique, a mixture of molecules is placed on a paper strip that is moistened with a buffer solution, and then an electric field is applied across the paper. Molecules with different charges will move towards the opposite electrode, and their mobility depends on their size and charge.

Determining the properties of glutamic acid, arginine, and valine

To understand the behavior of glutamic acid, arginine, and valine on paper electrophoresis, we need to know their properties, particularly their isoelectric points (pI) -- the pH at which the amino acid has no net charge. - Glutamic acid: An acidic amino acid with a carboxyl side chain. It has pI = 3.22. - Arginine: A basic amino acid with a guanidino side chain. It has pI = 10.76. - Valine: A nonpolar, aliphatic amino acid with no charged side chain. It has pI = 6.00.

Determining the charge of each amino acid at pH 6.0

At any given pH, the charge of an amino acid can be positive, negative, or neutral. We will determine the charge of each amino acid at pH 6.0: - Glutamic acid (pI = 3.22): Since pH 6.0 > pI, glutamic acid will have a negative charge at pH 6.0. - Arginine (pI = 10.76): Since pH 6.0 < pI, arginine will have a positive charge at pH 6.0. - Valine (pI = 6.00): Since pH 6.0 = pI, valine will have a neutral charge at pH 6.0.

Predicting the movement of amino acids on paper electrophoresis

Now that we know the charge of each amino acid at pH 6.0, we can predict how they will move in the electric field during electrophoresis: - Glutamic acid (negatively charged): It will move towards the anode (the positive electrode). - Arginine (positively charged): It will move towards the cathode (the negative electrode). - Valine (neutral charge): It will not move or will have minimal mobility since it has no net charge to be attracted to either electrode. As a result, the mixture of these three amino acids will show three distinct bands on the paper electrophoresis strip, each representing the location of the amino acid based on its charge and mobility at pH 6.0.