Apoprotein Content Research Articles

Canine lipoproteins and atherosclerosis. I. Isolation and characterization of plasma lipoproteins from control dogs.

Canine plasma lipoproteins were fractionated into four distinct classes by ultracentrifugation combined with Geon-Pevikon block electrophoresis and characterized with respect to physical and chemical properties. The distribution of plasma lipids and lipoproteins was quite unlike that in man, the dog having approximately five to six times as much high density as lower density lipoproteins. Despite the marked difference in distribution, human lipoprotein equivalents were present. Very low density lipoproteins (VLDL) isolated at density less than 1.006 g/ml were triglyceride-rich particles ranging in size from 260 to 900 Å in diameter. The density range from 1.006 to 1.063 g/ml contained two classes of lipoproteins: one closely resembled aolow density lipoprotein (LDL) with β mobility and a particle size of approximately 200 Å and the other (called HDL 1 ) was closely related to the high density lipoproteins with respect to immunochemical reactivity, electrophoretic mobility, and apoprotein content. The HDL 1 particles ranged in size from 100 to 350 Å in diameter and appeared to be unlike any of the commonly described human lipoproteins. High density lipoproteins called HDL 2 isolated in the density range from 1.087 to 1.21 g/ml were protein-rich particles ranging in size from 55 to 85 Å. The apolipoprotein patterns of VLDL, LDL, and HDL 2 on polyacrylamide gel electrophoresis were similar to those of the corresponding lipoproteins of man.

Absorptivity and quantum yeild of bleaching in bovine visual pigment 500.

VISUAL pigments are conjugated proteins containing either retinal or 3-dehydroretinal as the chromophoric prosthetic group. The molar absorptivity (e) of the pigments at their absorption maximum in the visible spectrum has been determined either by measuring the retinal or the apoprotein content in a given amount of visual pigment. Knowledge of the molar absorptivity of visual pigments is of practical importance because concentrations are most easily determined by spectro-photometric methods. In addition, this parameter has a theoretical interest in that it enables one to calculate the quantum yield (φ) of bleaching.