Defining the Speciation, Coordination Chemistry, and Lewis Acid Catalysis of Electronically Diverse Zinc Benzoates.

Zinc benzoates may provide an element of tunability that is not available to their ubiquitous acetate analogues. Unfortunately, the synthesis, speciation, and coordination chemistry of zinc benzoates are less developed than the acetates. In this study, we systematically investigate zinc benzoates to understand their propensity to favor solvate (Zn(OCAr)(L)) or cluster (ZnO(OCAr)) formation as well as their utility as metal complex precursors.

Advances in the separation, sensitive detection, and characterization of heparin and heparan sulfate.

Elucidation of the relationship between the structure and biological function of the glycosaminoglycans (GAGs) heparin and heparan sulfate (HS) presents an important analytical challenge mainly due to the difficulty in determining their fine structure. Heparin and HS are responsible for mediation of a wide range of biological actions through specific binding to a variety of proteins including those involved in blood coagulation, cell proliferation, differentiation and adhesion, and host-pathogen interactions. Therefore, there is a growing interest in characterizing the microstructure of heparin and HS and in elucidating the molecular level details of their interaction with peptides and proteins.

Heterogeneity of depolymerized heparin SEC fractions: to pool or not to pool?

In the structural analysis of heparin and heparan sulfate, it is customary to combine or pool like-sized fractions obtained by size-exclusion chromatography (SEC) of enzymatically derived heparin oligosaccharides. In this study, we examine the heterogeneity of preparative-scale SEC fractions obtained from enzymatic digests of porcine intestinal mucosa heparin. Each fraction was profiled by capillary electrophoresis with UV detection (CE-UV) using a 60 mM formic acid running buffer at pH 3.

Ultraperformance ion-pair liquid chromatography coupled to electrospray time-of-flight mass spectrometry for compositional profiling and quantification of heparin and heparan sulfate.

Heparin and heparan sulfate (HS) are important pharmaceutical targets because they bind a large number of proteins, including growth factors and cytokines, mediating many biological processes. Because of their biological significance and complexity, there is a need for development of rapid and sensitive analytical techniques for the characterization and compositional analysis of heparin and HS at the disaccharide level, as well as for the structure elucidation of larger glycosaminoglycan (GAG) sequences important for protein binding. In this work, we present a rapid method for analysis of disaccharide composition using reversed-phase ion-pairing ultraperformance liquid chromatography coupled with electrospray time-of-flight mass spectrometry ((RPIP)-UPLC-MS).

Separation and analysis of trace degradants in a pharmaceutical formulation using on-line capillary isotachophoresis-NMR.

NMR spectroscopy is widely used in the pharmaceutical industry for the structure elucidation of pharmaceutical impurities, especially when coupled to a separation method, such as HPLC. However, NMR has relatively poor sensitivity compared with other techniques such as mass spectrometry, limiting its applicability in impurity analyses. This limitation is addressed here through the on-line coupling of microcoil NMR with capillary isotachophoresis (cITP), a separation method that can concentrate dilute components by 2-3 orders of magnitude.

Chemical genetic interrogation of natural variation uncovers a molecule that is glycoactivated.

Natural variation in human drug metabolism and target genes can cause pharmacogenetic or interindividual variation in drug sensitivity. We reasoned that natural pharmacogenetic variation in model organisms could be systematically exploited to facilitate the characterization of new small molecules. To test this, we subjected multiple Arabidopsis thaliana accessions to chemical genetic screens and discovered 12 accession-selective hit molecules.

On-line NMR detection of microgram quantities of heparin-derived oligosaccharides and their structure elucidation by microcoil NMR.

The isolation and purification of sufficient quantities of heparin-derived oligosaccharides for characterization by NMR is a tedious and time-consuming process. In addition, the structural complexity and microheterogeneity of heparin makes its characterization a challenging task. The improved mass-sensitivity of microcoil NMR probe technology makes this technique well suited for characterization of mass-limited heparin-derived oligosaccharides.

Visualizing ion electromigration during isotachophoretic separations with capillary isotachophoresis-NMR.

Sample stacking techniques in electrophoresis are gaining popularity due to their ability to provide improved sensitivity and separation efficiency. The principles behind sample stacking and electrophoretic migration have been studied extensively. Nevertheless, there are still a number of observations and descriptions of ionic boundaries and migration modes for which the underlying principles are not yet fully understood.

Separation and analysis of nanomole quantities of heparin oligosaccharides using on-line capillary isotachophoresis coupled with NMR detection.

Glycosaminoglycans (GAGs) are important in a number of biological processes and are structurally altered in many pathological conditions. The complete determination of GAG primary structures has been hampered by the lack of sensitive and specific analytical techniques. Nuclear magnetic resonance spectroscopy (NMR) is a powerful tool for GAG structure elucidation despite its relatively poor limits of detection.