STRUCTURAL BASIS FOR DIFFERENCES BETWEEN ELH AND ECG

马促性腺激素eLH和eCG结合相同的受体， 显示LH和FSH活性，具有相同的氨基酸 序列，但其糖基化模式显著不同。 因此，在体内观察到它们之间的所有功能差异， 在体外仅由于糖基化。 eCG对 马LH受体比eLH小57- 75倍。 半衰期 循环中eCG的含量大于eLH。 人们普遍 eCG在生物学中用于促进卵泡发育的用途， 超数排卵本身作为目的或作为一种手段， 大量动物用于其他研究。 杂合激素是从不同的组合的完整的 ASN 56去糖基化eLH α或eCG α制剂，具有完整 eLH β和eCG β。 其他的混合体由完整的α- 与截短的des（121-149）eLH β或 des（121-149）eCG β制剂。 LH和FSH受体结果 结合试验表明，α Asn 56寡糖和β- 亚基O-连接的寡糖产生强烈的负面影响， 这些激素制剂的受体结合效力。 在 相反，α Asn 82和β Asn 13寡糖起地雷作用 在确定eLH和eCG之间的功能差异。 使用各种现代酶和化学修饰， eLH和eCG α和β的寡糖和多肽链 亚基，一组杂交激素缺乏特定的 将产生低聚糖。 这些混血儿的活动 在大鼠睾丸LH放射性配体试验中检测，大鼠睾丸Leydig细胞 在体外类固醇生成测定和在体内eCG生物测定中。 的 获得的信息将证实α Asn 56和β O-连接 寡糖对受体结合的影响最显著 活性，并将确定最重要的碳水化合物结构， 调节的体外类固醇生成和体内生物活性 这些荷尔蒙。 结构研究将确定α Asn 56的特征 和β-O-连接的寡糖， eLH和eCG之间的生物活性差异。 结果将有助于 了解蛋白质差异糖基化的特点， 垂体和胎盘 由于自然的独特性， 这些研究不能用重组DNA进行 技术.

The equine gonadotropins, eLH and eCG, bind the same receptors, display both LH and FSH activities, possess identical amino acid sequences, yet differ significantly in their glycosylation patterns. Therefore, all functional differences between them observed in vivo and in vitro are due only to glycosylation. The affinity of eCG for the equine LH receptor is 57- to 75-fold less than that of eLH. The half-life of eCG in circulation is greater than that of eLH. There is widespread use of eCG in biology for promoting follicular development and superovulation either as an end in themselves or as a means to produce large numbers of animals for other studies. Hybrid hormones were prepared from different combinations of intact of ASN56 deglycosylated eLH alpha or eCG alpha preparations with intact eLH beta and e CG beta. Other hybrids consisted of intact alpha- subunit preparations combined with truncated des(121-149)eLH beta or des(121-149)eCG beta preparations. The results of LH and FSH receptor binding assays revealed that alpha Asn56 oligosaccharides and beta- subunit O-linked oligosaccharides exerted a strong negative influence on the receptor binding potency of these hormone preparations. In contrast, alpha Asn82 and beta Asn13 oligosaccharides played a mine role in determining the functional differences between eLH and eCG. Using a variety of modern enzymatic and chemical modifications of oligosaccharides and polypeptide chains of eLH and eCG alpha and beta subunits, a panel of hybrid hormones deficient in specific oligosaccharides will be created. The activities of these hybrids will be tested in a rat testis LH radioligand assay, rat testis Leydig cell steroidogenesis assay in vitro and in an in vivo eCG bioassay. The information obtained will confirm that alpha Asn56 and beta O-linked oligosaccharides have the most significant effect on receptor binding activity and will identify the carbohydrate structures most important for modulating the in vitro steroidogenic and in vivo biological activities of these hormones. Structural studies will identify features of alpha Asn56 and beta O-linked oligosaccharides that are responsible for the differences in bioactivity between eLH and eCG. The results will help to understand the peculiarities of differential glycosylation of proteins in the pituitary and placenta. Because of the unique features of natural glycosylation these studies can not be performed with recombinant DNA technology.