Animal lipoproteins: chemistry, structure, and comparative aspects

Although use of plasma from the horse (Equus sp.) facilitated the earliest isolation of a soluble lipoprotein of constant composition by Macheboeuf in 1929 ( l ) , subsequent attention has centered upon the human lipoprotein system; numerous reviews in recent years attest to this (2-4).Such a situation is a reflection of man's susceptibility to cardiovascular disease and of the implication of the serum lipoproteins in its development.Knowledge of lipid transport systems in animals has advanced in recent years, particularly as a result of the extensive use of a number of higher animal species as experimental models for lipid and lipoprotein metabolism in man, albeit often under conditions of atherogenic diet.Some progress in this sphere is also due to the ever-increasing importance of foodstuffs of animal origin in human nutrition, which has in turn incited basic research into the nutrition of animals themselves and into their modes of lipid absorption and transport.It is pertinent to remark therefore that there is a paucity of data on the quantitative and qualitative characteristics of the major lipoproteins and apolipoproteins in a number of commonlyused species under normal dietary conditions.Moreover, data on animal lipoproteins are often disperse, although information up to 1975 has been reviewed by Mills (5).In addition, data are commonly subject to Abbreviations: Apo, apolipoprotein; VLDL, very low density lipoproteins of d < 1.006 g h l , unless otherwise defined; IDL, inter-