一项由密西根大学分析化学家Kristina Hakansson发明的一种新技术，可辨别癌细胞的多聚糖，为新的癌症诊断和治疗方法奠定了基础。
越来越多的证据显示，与癌细胞表面蛋白连接的多聚糖，也参与了肿瘤的生长和扩散。研究人员已经鉴定出了这种多聚糖，但是传统的分析方法却不是很有效。
Hakansson的研究小组证实，他们的技术可以用来鉴定多聚糖，并分析它们的结构特征。这项研究结果将刊载于4月15日的Analytical Chemistry上。
通常，分析化学的工作人员会利用质谱来分析蛋白质。在这个过程中，蛋白质需要进入质谱仪中，并通过加热来将它们变成碎片。不同片断的量可以提供与遗传蓝图有关的信息。这也就是所谓的shake-it-til-it-break。
但是，如果蛋白质上结合了其它基团如磷酸、硫酸或糖，那么这种鉴定方法就派不上用场了。为了解决这个问题，研究人员利用一种叫做电子捕获裂解（ECD, electron capture dissociation）的方法，来代替shake-it-til-it-break方法来使蛋白质分解。但是，这种方法需要至少携带两个正电荷。
Hakansson的研究组利用金属如钙和铁来携带必要的正电荷。而他们也首次证实，这种方法可用于选择性地分解蛋白质不同的化学键，该方法也可以用于测定含硫酸基团蛋白质、确定出蛋白质上硫酸基团的位置。
研究人员表示，这项工作目前还处于初步阶段，但是他们希望通过测量特殊的糖分子，研发出更精密的癌症诊断工具和治疗方法。
(资料来源 : biocompare)
部分英文原文：
Anal. Chem., 73 (18), 4530 -4536, 2001. 10.1021/ac0103470 S0003-2700(01)00347-X
Web Release Date: August 16, 2001 Copyright © 2001 American Chemical Society
Electron Capture Dissociation and Infrared Multiphoton Dissociation MS/MS of an N-Glycosylated Tryptic Peptide To Yield Complementary Sequence Information
Kristina Håkansson, Helen J. Cooper, Mark R. Emmett, Catherine E. Costello, Alan G. Marshall, and Carol L. Nilsson*
Center for Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, Mass Spectrometry Resource, Boston University School of Medicine, 715 Albany Street R-806, Boston, Massachusetts 02118-2526, and Institute of Medical Biochemistry, Göteborg University, Box 440, SE-405 30 Göteborg, Sweden
Received for review March 23, 2001. Accepted July 2, 2001.
Abstract
Glycoproteins are a functionally important class of biomolecules for which structural elucidation presents a challenge. Fragmentation of N-glycosylated peptides, employing collisionally activated dissociation, typically yields product ions that result from dissociation at glycosidic bonds, with little occurrence of dissociation at peptide backbone sites. We have applied two dissociation techniques, electron capture dissociation (ECD) and infrared multiphoton dissociation (IRMPD), in a 7-T Fourier transform ion cyclotron resonance mass spectrometer, in the investigation of an N-glycosylated peptide from an unfractionated tryptic digest of the lectin of the coral tree, Erythrina corallodendron. ECD provided c and z ions derived from the peptide backbone, with no observed loss of sugars. Cleavage at 11 of 15 backbone amine bonds was observed. The lack of cleavage at sites located close to the glycosylated asparagine residue may result from steric blocking by the glycan. IRMPD provided abundant fragment ions, primarily through dissociation at glycosidic linkages. The monosaccharide composition and the presence of three glycan branch sites could be determined from the IRMPD fragments. The two types of spectra, obtained with the same instrument, thus provide complementary structural information about the glycopeptide. The current result extends the applicability of ECD for glycopeptide analysis to N-glycosylated peptides and to peptides containing branched, highly substituted glycans.
