Ishimura K, Incefy G S, Wang J G, Komiyama T, Heimer E P, Felix A M, Unson C G, Khan S A, Erickson B W
Mol Immunol. 1986 Jul;23(7):701-7. doi: 10.1016/0161-5890(86)90080-5.
Thymosin alpha 1, an acidic 28-residue peptide, enhances immune function. We have described a radioimmunoassay for this thymic factor based on a rabbit antiserum raised against a thymosin alpha 1-(15-28) conjugate (Incefy et al., J. Immun. Meth. 1986, in press). The detailed antigenic specificity of this antiserum was determined by measuring the ability of synthetic segments and analogues of thymosin alpha 1 and related peptides to compete with radioiodinated Ac-Tyr-thymosin alpha 1-(15-28) in this radioimmunoassay. The antiserum bound segments Ac-(1-28), (15-28), (20-28) and (21-28) with nearly equal efficiency but failed to bind segments Ac-(1-10), (11-20), (19-24) and (22-28). Thus, the major immunoreactive site seen by the antiserum is the COOH-terminal segment (21-28) (Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-OH). Immunoreactivity of (21-28) was nearly abolished when the carboxylate groups of Glu-21, Glu-27 and Asn-28 were omitted separately. The antiserum bound to prothymosin alpha and thymosin alpha 11, which lack the alpha-carboxylate group of Asn-28, with 0.9 and 0.2%, respectively, of the efficiency of thymosin alpha 1. But it bound nonspecifically to parathymosin alpha, which contains the internal segment . . . -Glu-Val-Val-Glu-Glu-Glu-Glu-Asn- . . . . Residues Glu-21, Glu-27 and Asn-28 of thymosin alpha 1 may be important features of the antigenic site through their ability to induce helical structure, through the ability of their negatively charged carboxylate groups to bind to specific sites on the antibody or both.
胸腺素α1是一种由28个氨基酸组成的酸性肽，可增强免疫功能。我们已经描述了一种针对这种胸腺因子的放射免疫分析方法，该方法基于用针对胸腺素α1-(15-28)缀合物产生的兔抗血清（因塞菲等人，《免疫学方法杂志》，1986年，即将发表）。通过测量胸腺素α1及其相关肽的合成片段和类似物在该放射免疫分析中与放射性碘化的Ac-Tyr-胸腺素α1-(15-28)竞争的能力，确定了该抗血清详细的抗原特异性。该抗血清以几乎相同的效率结合片段Ac-(1-28)、(15-28)、(20-28)和(21-28)，但未能结合片段Ac-(1-10)、(11-20)、(19-24)和(22-28)。因此，抗血清所见的主要免疫反应位点是COOH末端片段(21-28)（Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-OH）。当分别省略Glu-21、Glu-27和Asn-28的羧基时，(21-28)的免疫反应性几乎消失。该抗血清分别以胸腺素α1效率的0.9%和0.2%与缺乏Asn-28的α-羧基的前胸腺素α和胸腺素α11结合。但它与含有内部片段……-Glu-Val-Val-Glu-Glu-Glu-Glu-Asn-……的副胸腺素α非特异性结合。胸腺素α1的Glu-21、Glu-27和Asn-28残基可能因其诱导螺旋结构的能力、其带负电荷的羧基与抗体上特定位点结合的能力或两者兼而有之，而成为抗原位点的重要特征。
