Applications of New Mass Spectral Techniques

基质辅助激光解吸电离（MALDI）质谱、电喷雾电离质谱（ESI/MS）、串联质谱（MS/MS）、在线液相色谱-质谱（LC/MS）、毛细管电泳（CE）和质谱联用以及精确质量测量是当前感兴趣的技术。MALDI/MS与高效液相色谱（HPLC）和CE的离线组合正在研究中，作为分析复杂生物和合成混合物的替代方法。这种方法涉及自动收集和点样MALDI样品板上的HPLC洗脱液，用于随后的MS分析，其可以包括精确的质量测量和源后衰变碎片分析或MS/MS。这种方法的优点是在线LC/MS的原始分离样品的存档的生成用于再分析。一个类似的方法正在应用与CE，其中on-linesample浓度技术，涉及电泳聚焦的大体积样品注射之前，峰收集正在研究作为一个delicative-scale的方法，离线结合CE与高分辨率MALDI/MS。我们的目标是自动化这个过程。MALDI/MS技术的初步研究表明，利用特殊的能量转移表面和直接激光解吸电离（LDI）技术，在不需要基质的情况下，可以快速分析小分子物质，而以限制性二酰化甘油（DAG-lactones）为骨架的合成衍生物是蛋白激酶C（PK-C）的有效激动剂。根据包含R1和R2的取代基的结构，这些DAG-内酯似乎具有一定程度的PK-C同工酶特异性。一个固相组合的方法被应用在LMC研究化学多样性在R1和R2，以产生更具体的C1结构域配体。重要的是，这些合成库的快速表征和生物学评价之前建立其结构。用于较大的合成DAG-内酯文库的初始表征的快速质谱方法之一是FAB/MS混合物分析。DAG-内酯混合物的分析与单独的分析直接相关，大大减少了待检测样品的数量，提高了分析周转率，并可进行精确的质量测量。流动注射ESI/MS不适合分析这些DAG-内酯，因为它们的高亲油性和有限的碱性。流动注射-大气压化学电离产生的光谱，包括MH+以及各种碎片和溶剂加合物离子。这后一种方法似乎是补充FAB/MS的光谱信息。MALDI/MS也似乎是一种有用的工具，这些小分子库的快速表征，虽然可变的碱金属离子阳离子化复杂的光谱解释。无矩阵MALDI目前正在研究中，作为解决这个问题的方法，并提供一个更快速的分析方法。我们的目标是在一天内对所有96个文库组分进行结构表征。

Matrix-assisted laser desorption ionization (MALDI) mass spectrometry, electrospray ionization mass spectrometry (ESI/MS), tandem mass spectrometry (MS/MS), on-line liquid chromatography-mass spectrometry (LC/MS), combined capillary electrophoresis (CE) and mass spectrometry, and accurate mass measurement are the techniques of current interest. The off-line combination of MALDI/MS with high-performance liquid chromatography (HPLC) and with CE is under investigation as an alternate approach for the analysis of complex biological and synthetic mixtures. This approach involves automatically collecting and spotting the HPLC eluent on a MALDI sample plate for subsequent MS analysis, which can include accurate mass measurement and post-source decay fragmentation analysis or MS/MS. An advantage of this approach over on-line LC/MS is the generation of an archive of the original separated sample for reanalysis. A similar approach is being applied with CE where on-linesample concentration techniques involving electrophoretic focusing of large-volume sample injections prior to peak collection are being investigated as a preparative-scale method for the off-line combination of CE with high resolution MALDI/MS. Our goal is to automate this process. Preliminary studies of MALDI/MS using special energy-transferring surfaces and direct laser-desorption ionization (LDI) without the presence of a matrix show promise for the rapid analysis of small molecules.Synthetic derivatives built on a constrained diacylated glycerol scaffold (DAG-lactones) have been identified as potent agonists of protein kinase C (PK-C). Depending on the structure of the substituents comprising R1 and R2, these DAG-lactones appear to have some degree of PK-C isozyme specificity. A solid-phase combinatorial approach is being applied in the LMC to investigate chemical diversity at R1 and R2 in order to produce more specific C1 domain ligands. It is important that these synthetic libraries be rapidly characterized and their structures established before biological evaluation. One of the rapid mass spectral approaches employed for the initial characterization of the larger synthetic DAG-lactone libraries is FAB/MS mixture analysis. Analysis of DAG-lactone mixtures correlates directly with individual analysis, substantially reduces the number of samples to be examined, results in enhanced analytical turn-around and is amenable to accurate mass measurement. Flow-injection ESI/MS is not suitable for analysis of these DAG-lactones because of their high lipophilicity and limited basicity. Flow injection-atmospheric pressure chemical ionization produces spectra that consist of MH+ as well as various fragment and solvent-adduct ions. This later approach appears to be complementary to FAB/MS in terms of spectral information. MALDI/MS also appears useful as a tool for the rapid characterization of these small molecule libraries although variable alkali metal ion cationization complicates spectral interpretation. Matrix-less MALDI is currently under investigation as an approach to resolve this problem and provide an even more rapid analysis approach. Our goal is the structural characterization of all 96 library components in one day.