Her Cheng, Westler William M, Yang Thao
Department of Chemistry, University of Wisconsin - Eau Claire, USA.
Department of Biochemistry, University of Wisconsin, USA.
JSM Chem. 2013 Jan 1;1(1). Epub 2013 Oct 17.
In this study we investigated to see whether or not a shortened MUC1 mucin peptide epitope with the sequence GVTSAPD containing a single prolyl residue would still bind specific monoclonal antibody as its native sequence (e.g., PDTRP), known to be the specific recognition site on the Variable Number Tandem Repeat (VNTR) region of MUC1 mucin by the immune system. The affinity of GVTSAPD peptide to a mouse Muc1 mucin specific monoclonal antibody (clone 6A4, IgG1 isotype) was investigated by Saturation Transfer Difference NMR spectroscopy (STD NMR). Results showed that the shortened mucin epitope GVTSAPD still retained affinity to Muc1 specific monoclonal antibody (mAb) while one that lacks the prolyl residue at position 6 lost its affinity, which suggests that P is necessay for antibody binding. The interactions observed by STD NMR occurred strongest at the P side chain H's (βH and γH); the PH showed lower degree of saturation transfer effect. Minor interactions also occurred at the methyl groups of V T and A. Mucin peptides derived from the VNTR region have been the target of cancer vaccine research, thus properties associated with mucin peptide structure, conformation and antibody interaction are central to peptide design or engineering towards that end.
在本研究中，我们调查了一种缩短的MUC1粘蛋白肽表位，其序列为GVTSAPD，含有单个脯氨酰残基，是否仍能像其天然序列（如PDTRP）一样结合特异性单克隆抗体，已知该天然序列是免疫系统对MUC1粘蛋白可变数目串联重复序列（VNTR）区域的特异性识别位点。通过饱和转移差异核磁共振波谱（STD NMR）研究了GVTSAPD肽与小鼠Muc1粘蛋白特异性单克隆抗体（克隆6A4，IgG1亚型）的亲和力。结果表明，缩短的粘蛋白表位GVTSAPD仍保留对Muc1特异性单克隆抗体（mAb）的亲和力，而在第6位缺乏脯氨酰残基的表位则失去了亲和力，这表明脯氨酸对于抗体结合是必需的。STD NMR观察到的相互作用在脯氨酸侧链的氢原子（βH和γH）处最强；脯氨酸的氢显示出较低程度的饱和转移效应。在缬氨酸、苏氨酸和丙氨酸的甲基处也发生了轻微的相互作用。源自VNTR区域的粘蛋白肽一直是癌症疫苗研究的目标，因此与粘蛋白肽结构、构象和抗体相互作用相关的特性是为此目的进行肽设计或工程的核心。
