A14、A19、B16及B26-〔^(125)碘〕单碘原子碘化胰岛素免疫活性的异质性

Heterogeneity of the Immunoreactivity of A14,A19,B16 and B26-(^(125)I) Monoiodoinsulin to Different Species of Anti-Insulin Immunosera

用乳过氧化物酶标记法,并在反应液中加6mol尿素能得到A14、A19、B16及B26-[^(125)碘]单碘胰岛素。4种标记胰岛素分别与16株豚鼠抗胰岛素免疫血清作结合反应,以Scatchard法求亲和常数(Ka)比较分析。结果表明胰岛素的碘标记位置不同,对免疫血清的亲和力有明显影响。对此现象产生的原因及意义作了讨论。

By using lactoperoxidaseoxidation with 6 mol. urea in the reactionmedium, the four tyrosine residues conta-ined in insulin molecule were iodinated asmonoiodoinsulins. These tracers, namelyA14, A19, B16 and B26-(^(125)I) monoiodo-insulins were separated with polyacryl-amide gel electrophoresis+QAE-SephadexA25 chromatography. The present studydemonstrated that the radiochemical purityof these tracers was high (>98%) and theapecific radioactivity also high. The bind-ing of these tracers to surplus insulinantibody was more than 95%. These fourtracers were tested in two RIA systemsagainst 35 species of guinea-pig anti-insu-lin immunosera to compare their immuno-reactivity (Ka, Scatchard analysis) to eachimmunoserum. The two RIA systems wereantibody dilution and selfdisplacement, andin both of them. only iodinated insulin andinsulin antibody were present in the reac-tion fluid. The results showed that for 16antiinsulin immunosera, Ka for A14, A19.B16 or B26-monoiodoinsulin were signifi-cantly different, and for the rest 19 immu-nosera no significant difference could bedetected. The possible mechanism andimplication of this phenomenon werediscussed.