If the PI of a Peptide is 4

Question

If the pI of a peptide is 4.6, ____ might be present while ____ would probably be absent.
A) Glu / Lys
B) His / Ser
C) Arg / His
D) Asp / Gly
E) Cys / Tyr

Accepted Answer

The pI (isoelectric point) of a peptide is the pH at which the peptide carries no net charge. A pI of 4.6 is acidic, suggesting the presence of acidic amino acids like Glutamic acid (Glu) and the absence of basic amino acids like Lysine (Lys), which would increase the pI.