Oppezzo O J, Biscoglio de Jiménez Bonino M, Cascone O, Nowicki C, Blumgrund V, Santomé J A, Fernández H N
Acta Physiol Pharmacol Latinoam. 1984;34(2):175-84.
The bovine growth hormone dimeric form covalently stabilized by cross-linking with dimethyl suberimidate (DMS) and the hormone modified by DMS without forming covalent links with other hormone molecules (DMS-bGH) were oxidized with chloramine-T at molar-ratios of 2 and 50 with respect to methionine content. The extent of oxidation undergone by each methionine residue, estimated on the purified tryptic peptides, closely resembled that obtained for the native hormone, thus suggesting that methionine residues are not involved in the protomers interaction area. Evaluation of the reactivity of tyrosine residues toward tetranitromethane indicated that, in both the covalent dimer and DMS-bGH, tyrosine residues 35, 174 and 142 are the more susceptible to undergo reaction. Net charges can be induced in the iodotyrosine residues in the iodinated hormone, by setting the pH at 10.5. At this pH, dissociation of a fraction of uniformly iodinated hormone was observed in the derivatives containing 2 or more iodine atoms, indicating that tyrosine residues might integrate the contact area between protomers.
通过与辛二亚氨酸二甲酯（DMS）交联而共价稳定的牛生长激素二聚体形式以及经DMS修饰但未与其他激素分子形成共价键的激素（DMS-bGH），相对于甲硫氨酸含量，以2和50的摩尔比用氯胺-T进行氧化。在纯化的胰蛋白酶肽段上估计的每个甲硫氨酸残基的氧化程度，与天然激素所获得的氧化程度非常相似，因此表明甲硫氨酸残基不参与原体相互作用区域。酪氨酸残基对四硝基甲烷的反应性评估表明，在共价二聚体和DMS-bGH中，酪氨酸残基35、174和142更容易发生反应。通过将pH值设定为10.5，可以在碘化激素的碘酪氨酸残基中诱导净电荷。在此pH值下，在含有2个或更多碘原子的衍生物中观察到一部分均匀碘化激素的解离，这表明酪氨酸残基可能整合了原体之间的接触区域。
