Purification of insulin-like peptides from insect haemolymph and royal jelly

Abstract Insulin-like peptides from the haemolymph of the tobacco hornworm, Manduca sexta L. and from royal jelly of the honey bee, Apis mellifera L., were purified by acid extraction, ion-exchange chromatography, gel filtration and affinity chromatography. Quantities detected were 500 and 25 pg porcine insulin equivalents per gram of lyophilized material for haemolymph and royal jelly, respectively. M. sexta insulin was similar to vertebrate insulin in solubility, chromatographic, immunological and biological properties. Amino acid compositions were comparable except for serine, leucine and phenylalanine. The A. mellifera peptide had similar properties, but was not isolated in large enough quantity to determine its amino acid composition. These results demonstrated that insect insulin and vertebrate insulin are structurally similar.