Norton R S, Norton T R
J Biol Chem. 1979 Oct 25;254(20):10220-6.
Natural-abundance 13C NMR spectra (at 15.04 MHz) of the polypeptide cardiac stimulant Anthopleurin-A are presented. The spectra contain many resolved one- and two-carbon resonances from carbonyl and aromatic carbons and a few resolved resonances from aliphatic carbons. Most of these have been assigned to individual carbons in the protein. The effect of pH on the 13C spectrum has been investigated. In conjunction with the resonance assignments, this yields estimates for the pK alpha values of the COOH-terminal and NH2-terminal residues, the side chain carboxylate of 1 of the 2 aspartic acid residues, and the imidazolium groups of the 2 histidine residues. The effects of the lanthanides La3+ and Gd3+ on the spectrum have also been studied. The results suggest that there are at least two binding sites, and further studies will be required to characterize these before they can be utilized as an aid in structural mapping. Finally, the results are discussed in relation to a postulated model for the mode of action of Anthopleurin-A.
本文展示了多肽心脏兴奋剂Anthopleurin-A的天然丰度13C NMR谱（15.04 MHz）。该谱包含许多来自羰基和芳香族碳的可分辨的单碳和双碳共振峰，以及一些来自脂肪族碳的可分辨共振峰。其中大多数已被指定到蛋白质中的各个碳上。研究了pH对13C谱的影响。结合共振归属，可得出COOH末端和NH2末端残基、2个天冬氨酸残基中1个的侧链羧酸盐以及2个组氨酸残基的咪唑鎓基团的pKα值估计。还研究了镧系元素La3+和Gd3+对该谱的影响。结果表明至少有两个结合位点，在将它们用作结构映射的辅助工具之前，还需要进一步研究来表征这些位点。最后，结合Anthopleurin-A作用模式的假设模型对结果进行了讨论。
