Determination of human apolipoprotein E by electroimmunoassay.
1. Apolipoprotein E ("arginine-rich" polypeptide) was isolated from delipidized human very low density lipoproteins by agarose column chromatography in the presence of 6 M guanidine-hydrochloride. 2. An electroimmunoassay ("rocket" electrophoresis) is described for quantitative determination of human serum apolipoprotein E. Purified apolipoprotein E was used for the preparation of monospecific antisera and standardization of assay. This sensitive, specific, rapid (time required for the completion of the assay is 5 h) and precise (the within- and between-assay coefficients of variation are 5 and 8%, respectively) assay is applicable to measurement of apolipoprotein E in whole serum and density classes. The results correlated well with those obtained by radial immunodiffusion (r = 0.85). 3. Serum apolipoprotein E levels of normal subjects and hyperlipoproteinemic phenotypes IIa, IIb and IV were the same (10 to 16 mg/100 ml). In contrast, patients with type III and V hyperlipoproteinemias had markedly elevated serum apolipoprotein E levels )27 and 25 mg/100 ml, respectively). The apolipoprotein E in serum of normolipidemic subjects was equally distributed among three major lipoprotein density classes: d less than 1.030 g/ml (27%), d 1.030-1.063 g/ml (36%)and d 1.063-1.21 g/ml (37%).
D000596:Amino Acids / Q000032:analysis; D001059:Apoproteins / Q000097:blood*; D001120:Arginine / Q000032:analysis; D002784:Cholesterol / Q000097:blood; D006146:Guanidines; D006801:Humans; D006949:Hyperlipidemias / Q000097:blood; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D008074:Lipoproteins / Q000097:blood*; D008079:Lipoproteins, VLDL / Q000097:blood; D014280:Triglycerides / Q000097:blood
D000596:Amino Acids; D001059:Apoproteins; D006146:Guanidines; D008074:Lipoproteins; D008079:Lipoproteins, VLDL; D014280:Triglycerides; D001120:Arginine; D002784:Cholesterol