Lipovitellin. 2. The influence of water on the stability of lipovitellin and the effects of freezing and of drying

Abstract

Decomposition of the lipoprotein was minimized by rapid freezing and thawing, and was not increased by very low freezing temps. Further changes occurred during storage in the frozen state at temps. down to -29[degree], and at -3[degree] the lipoportein became completely insoluble. Lipovitellin could be freeze-dried at approx. neutral pH with but little decomposition, and was then comparatively stable at low storage temps., or even at 37[degree] if very dry. In equilibrium with atmospheres of high relative humidity the moist solid decomposed much more rapidly than either the dry solid or the fully moistened or dispersed lipoprotein. About 25% of the lipid of freshly freeze-dried lipovitellin was readily extractable with ether, but on moistening (at neutral, but not at acid, pH) most of this lipid again became extractable only with difficulty. The parallelism between the 2 criteria of decomposition used, namely dis-persibility in NaCl soln.-ether and extractability of the lipid with ether, was not complete.