What is the net charge of this peptide at pH 3? show charges at pH 3 of all possible groups that could be ionized to support your answer

WHETCGYTMKV

I got +1 but apparently this is wrong.... I thought cysteine and tyrosine were ionizable amino acids, can someone please explain this to me???

because the professor won't!

My Work:

W-NH3+

H-NH

E-COOH

C-SH

Y-OH

K-NH3+

V-COO-

-1+1+1 = +1