A study of the astaxanthin-lipovitellin, ovoverdin, isolated from the ovaries of the lobster, Homarus gammarus (L.)

Abstract

1. 1. The subunit structure of ovoverdin, the astaxanthin-lipovitellin of lobster ovaries and eggs, isolated from Homarus gammarus (L.) is distinct from that reported in the literature for the pigment of Homarus americanus. 2. 2. The complex of H. gammarus has absorption maxima at ca 465 and 667 nm at 25°C and dissociates in sodium dodecylsulphate-polyacrylamide electrophoresis (SDS-PAGE) into two glycoprotein subunits of ca 140 × 10 3 and 105 × 10 3 daltons apparent molecular size. 3. 3. The visible absorption spectrum of the pigment alters reversibly between 5 and 25°C, for freshly prepared material, with the absorption bands bathochromically shifted at the lower temperature; the longer wavelength absorption band becomes fine structured as the temperature is lowered. 4. 4. A colourless lipovitellin is present in preparations of ovoverdin. The lipovitellin, only partially separated from ovoverdin in gel filtration on Agarose 6B, is resolved from the latter pigment in PAGE. It gives two glycoprotein subunits of ca 125 × 10 3 and 105 × 10 3 daltons apparent molecular size in SDS-PAGE. 5. 5. Precipitation of ovoverdin at low ionic strength is associated with the presence of a contaminating protein of ca 96 × 10 3 daltons apparent molecular size in SDS-PAGE. 6. 6. Storage of ovoverdin preparations at pH 7 gives rise to a red coloured product in which both subunits have been proteolytically degraded. 7. 7. The number of astaxanthins bound per ovoverdin molecule is discussed.