gly-val-hyp-cys-arg-cys-asp-ser-asp-gly-pro-ser-val-his-gly-asn-thr-leu-ser-gly-thr-val-trp-val-gly-ser-cys-arg-ser-gly-trp-his-lys-cys-asn-asp-glu-tyr-asn-ile-ala-tyr-glu-cys-cys-lys-gln. it has six cysteine amino acids. they are linked by three disulfide bonds between residues at positions 4– 44, 6 –34 and 27– 45.