Burgon P G, Stanton P G, Pettersson K, Robertson D M
Prince Henry's Institute of Medical Research, Monash Medical Centre, Clayton, Vic., Australia.
Reprod Fertil Dev. 1997;9(5):501-8. doi: 10.1071/r96123.
To establish whether sialic acid content is responsible for an observed 7-8-fold variability in bioactivity in vitro of highly purified human pituitary luteinizing hormone (hLH) isoforms, the bioactivity in vitro, radioreceptor activity and immunoactivity of hLH isoforms were determined before and after enzymatic desialylation. Three immunofluorometric assays with different hLH specificities allowed characterization of 13-24 pituitary hLH isoform preparations of pI 7.03-8.98 in terms of sialic acid content (1-5 sialic acid residues per LH molecule), bioactivity in vitro (4030-30,000 I.U. mg[-1]), radioreceptor activity (6420-25,400 I.U. mg[-1]) and hLH immunoactivity (2900-4400 to 18,300-27,300 I.U. mg[-1]). Significant positive correlations between sialic acid content and either immunoactivity or in vitro bioactivity were observed, whereas radioreceptor activity showed a curvilinear response. Following more than 90% removal of sialic acid, both in vitro bioactivity and radioreceptor activity were increased, although specific activity still differed between isoforms; immunoactivities were unaffected. It is concluded that the presence of the sialic acid residue(s) on hLH isoforms does partially contribute to the in vitro bioactivity and radioreceptor activity of the isoforms, but that hLH immunoactivity is independent of sialic acid content.
为确定唾液酸含量是否是造成高纯度人垂体促黄体生成素（hLH）同工型体外生物活性出现7至8倍差异的原因，在酶促去唾液酸化前后分别测定了hLH同工型的体外生物活性、放射受体活性和免疫活性。三种具有不同hLH特异性的免疫荧光测定法能够根据唾液酸含量（每个LH分子含1至5个唾液酸残基）、体外生物活性（4030 - 30,000 I.U. mg[-1]）、放射受体活性（6420 - 25,400 I.U. mg[-1]）以及hLH免疫活性（2900 - 4400至18,300 - 27,300 I.U. mg[-1]）对13 - 24种pI为7.03 - 8.98的垂体hLH同工型制剂进行表征。观察到唾液酸含量与免疫活性或体外生物活性之间存在显著正相关，而放射受体活性呈曲线反应。在去除超过90%的唾液酸后，体外生物活性和放射受体活性均有所增加，尽管同工型之间的比活性仍存在差异；免疫活性未受影响。得出的结论是，hLH同工型上唾液酸残基的存在确实部分促成了同工型的体外生物活性和放射受体活性，但hLH免疫活性与唾液酸含量无关。
