Comparative Analysis and Validation of Different Steps in Glycomics Studies.

Large-scale glycomics studies enable identification of aberrant glycosylation patterns in disease and provide information about functional relevance of individual glycans through genome-wide association studies. Developed high-throughput methodologies have to be sensitive, robust, and stable during long periods of time (few months) to be able to reliably detect small biological variations in glycosylation. Here, we describe a simple, robust, and affordable protocol for immunoglobulin G N-glycan analysis by hydrophilic interaction liquid chromatography-ultra-performance liquid chromatography (HILIC-UPLC), as well as useful strategies for method optimization: Plackett-Burman screening design and analysis of source of variation. We put our focus on experimental design for high-throughput glycan analysis, critical steps in sample preparation procedure for obtaining high-quality data, and propose a validation protocol relevant for high-throughput methods in terms of their long-term robustness and ability to detect biologically relevant changes in glycosylation. The quality of the procedure was assessed by employing appropriate experimental designs and subsequent statistical techniques.

High-throughput glycomics: optimization of sample preparation.

Glycosylation affects structure, folding, and function of numerous proteins. Aberrant glycosylation has been shown to be associated with different diseases. A wide range of analytical methods is available for glycan analysis of antibodies (mainly IgG), but analysis of plasma glycans is less established due to additional challenges encountered with higher complexity of the sample. Here we describe development and optimization of a high-throughput sample preparation method for hydrophilic interaction liquid chromatography and ultra-performance liquid chromatography analysis of plasma N-glycans. Clean-up of labeled glycans was found to be the largest source of variation, and we tested cellulose, silica gel, Bio-Gel, and hydrophilic GHP filter as stationary phases for solid-phase extraction. All stationary phases were shown to be suitable for purification of labeled glycans, but GHP filter plate in combination with cold 96% acetonitrile had the highest reproducibility and was easiest to work with. The method was further optimized with Plackett-Burman screening design and validated in terms of analysis of major step variation and between-day and between-person variation. The developed method is fast, cost-effective, and easy to perform, and it has very good reproducibility during long period of time, enabling the detection of biological variability of the plasma N-glycome.