Which of the following is a dipeptide?
Carnosine is a dipeptide, formed by combination of beta alanine and histidine. Carnosine is a major constituent of muscles. It can activate myosin contraction. Hydrolysis of carnosine to beta alanine and histidine is done by carnosinase. Inherited deficiency of this enzyme will lead to carnosinuria.
Reference: Vasudevan 7th  ed, pg 215
carnosine
Glutathione
Glucagon
β-Lipoprotein