Studies on the apoproteins of the major lipoprotein of the yolk of hen's eggs II. The dimer-tetramer transition of apovitellenin I.
Further studies have been made of the physical properties of hen's apovitellenin I, the principal low-molecular-weight protein from the high-lipid low density lipoprotein of the yolk of hen's eggs. The methods used included chromatography, sedimentation, viscosity, optical rotation, and spin labelling; the solvents used were aqueous urea, and, for some experiments, aqueous formamide. It is concluded that a neutral pH the protein is present in these solvents as an aggregate of molecular weight 36000 corresponding to a tetramer. Below about pH 4-5 solutions of the tetramer increased greatly in viscosity; furthermore, a covalently bound spin label increased in mobility. These changes were reversible and were apparently the result of dissociation of the tetramer to a dimer. This disociation did not involve a change in the proportion of alpha-helix. In contrast to the results of previous experiments, it now seems probably that the apovitellenin I dimer is stabilized by an interchain disulphide bond.
D000818:Animals; D001053:Apolipoproteins; D002645:Chickens; D004527:Egg Proteins; D004530:Egg Yolk / Q000032:analysis*; D004578:Electron Spin Resonance Spectroscopy; D005260:Female; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D009994:Osmolar Concentration; D011487:Protein Conformation; D014783:Viscosity
D001053:Apolipoproteins; D004527:Egg Proteins