The Amino Acid Sequence of a Protein (Apovitellenin I) From the Low-density Lipoprotein of Emu Egg Yolk

Abstract

The amino acid sequence of apovitellenin I from emu (Dromaius novae-hollandiae) egg yolk has been determined. Difficulties were encountered during sequencing, due to a labile Tyr-Val bond, which was hydrolysed readily by trypsin, chymotrypsin and pepsin. By use of a sequenator, this bond was easily characterized. The protein contains 84 residues and is devoid of half-cystine and histidine. Hydrophobic residues occur in clusters; two very hydrophobic sequences of 12 and 13 residues are present. A very hydrophilic sequence of seven residues contains nearly one-third of all side-chain charges in the molecule; the remainder of the polar residues are scattered throughout the sequence. In a number of instances, residues with opposite charges occur in adjacent positions.