Question

Some proteins and antibodies are susceptible to pH damage. In order to prevent this damage, what would be the most efficient and effective additional step to perform at the end of the elution process?

1) 0.1 M glycine⋅HCl, pH 3.0
2) 0.1 M NaCl, pH 7.0
3) 1 M Tris⋅HCl, pH 8.5
4) 0.7 M KOH, pH 13.85

Answer 1

To prevent pH damage to proteins and antibodies, using 0.1 M NaCl at pH 7.0 is the most efficient step after the elution process to stabilize the proteins around their isoelectric pH.

Step-by-step explanation:

Efficient Step to Prevent pH Damage to Proteins and Antibodies

To prevent pH damage to proteins and antibodies at the end of the elution process, the most efficient and effective step would be to use a solution that can maintain the pH near to the isoelectric pH of the proteins, where they are most stable. Given the choices, 0.1 M NaCl, pH 7.0 would be appropriate for proteins that are stable around neutral pH. For proteins with an isoelectric point close to neutral pH, this buffer would help in stabilizing them after the elution process by keeping the pH environment around 7.0, which is typically the physiological pH at which most proteins are stable.

It is important to understand that isoelectric pH is where a protein has an equal number of positive and negative charges, and thus will not move in an electric field and tend to precipitate. This suggests that buffers should be chosen to approximate this pH, especially when eluting proteins in a purification process, to maintain their stability and prevent degradation or precipitation.