Question

What is the net charge of the peptide arg-ala-phe-leu at ph 8?

Answer 1

The structure of this oligopeptide is attached:

It consists of arginine - alanine - phenylalanine and leucine

From the picture we can see that N terminus charge is +1
Also Arginine is considered as basic amino acid with charge +1
C terminus charge is -1

At pH = 8, the whose pKa are less than pH will be deprotonated and the net charge will be +1

So the net charge of this oligopeptide is +1 at pH = 8