Which of these proteins in mammals show only primary and secondary structures?

oxytocin

keratin

hemoglobin

Which of these proteins in mammals show only primary and secondary structures - Keratin. Proteins like keratin are made up of multiple peptide chains (polypeptide); these are group of amino acids joined by peptide bonds. [ The sequence of amino acids in a protein is the primary structure while the specific shape in which it is folded (alpha or beta) is called the secondary