Question

What was the purpose of the 0.1m sodium phosphate buffer in the protein isolation procedure? what is the general "rule of thumb" for determining the buffering range? what is the range of sodium phosphate?

Answer 1

The 0.1M sodium phosphate buffer is used in the protein isolation procedure to maintain a specific pH. The buffering range for a buffer is usually within ±1 unit of its pKa value. The range of sodium phosphate depends on the specific concentration used.

Step-by-step explanation:

The purpose of the 0.1M sodium phosphate buffer in the protein isolation procedure is to maintain the pH of the solution at a specific value. Buffers help to resist changes in pH when small amounts of acid or base are added to the solution. The 0.1M sodium phosphate buffer is used because it has a buffering range within the desired pH range.

The general rule of thumb for determining the buffering range is that a buffer is most effective when the pH is within ±1 unit of its pKa value. The pKa value is a measure of the acidity of the buffer.

The range of sodium phosphate depends on the specific concentration used. In the protein isolation procedure, a 0.1M sodium phosphate buffer is used, so the range would be within ±1 unit of the pKa value for sodium phosphate.

Answer 2

The buffer maintains the requisite pH of the solution even with addition of small amounts acid or base in the solution. This protects the integrity of the protein which is greatly influenced by pH of the solution. This is helped by the fact that a buffer is comprised of a weak acid (HA) with its conjugate base (A-) that attenuate the effects of the added acid or base.

As a general rule of thumb, the relative amounts of acid and base in a buffer should not differ by more than tenfold. This is because as this ratio changes in the endeavor to change the pH of the buffer, the less effective the buffering capacity of the buffer becomes. The best buffer is one where the pH of the buffer is equal to its pKa.

The range of sodium phosphate buffer is 5.8 to 8. This means that within these pH ranges, the buffer can easily moderate the pH of the solution by maintaining a relatively constant levels of H+ and OH- ions even with the addition of a small amount of strong acid or base.