Question

Estimate the isoelectric point of a ser–his dipeptide. explain why this value is only an estimate.

Answer 1

A dipeptide bond connects two amino acids. Ser stands for Serine while His stands for Histidine. Isoelectric point is when all charges of the two amino acids cancel out. This can be estimated by finding the average of the isoelectric points (pI) of the two amino acids.

Serine: pI = 5.68
Histidine: pI = 7.59

Average pI = (5.68 + 7.59)/2 = 6.635

This is only a rough estimate because an arithmetic average will not coincide with the biochemistry of the amino acids. The true value of the isolectric point is determined through experimentation. However, it would be more ore less around 6.635.