See also Lectin Affinity chromatography under Affinity Purification 

Definitions

Glycan: refers to the carbohydrate portion of a glycoconjugate, such as a glycopeptide, glycoprotein, glycolipid or proteoglycan. Regnier (US8,568,993) 

Glycomics is the systematic study of protein-glycan interaction and function. Glycans are information rich molecules composed of complex carbohydrates (sugars or polysaccharides) that are often attached to proteins and lipids. Studying glycomics is not an easy task due to linkage forms(e.g., alpha1-3, beta 1-4) and branching events that increase the structural complexity of glycans. Furthermore, glycans can not be directly sequenced and synthesized like DNAs and proteins.

Diagnosis of Disease based on Glycosylation Profile

Regnier (US8,568,993) teaches a method for detecting the presence or absence of sieases such as cancer by obtaining two or more sample glycopeptides from a subject and two or more reference glycopeptides and then comparing the sample glycopeptides or glycoproteins with the reference glycopeptides and detecting a difference in glycosylation state between them. 

Glycosylation and Cancer:

Lubman (WO2007/112082) discloses methods for the identification of glycosylated perotines and protein glycosylation patterns. In some embodiments, the method comprises treating a protein sample with a lecitn affinity chromatography apparatus under conditions such that it enriches the protein sample for glycosylated proteins to generate a glycosylated protein enriched sample and then separating the glycosylated protein enriched sample with a liquid chromatography apparatus. Lectins are carbohydrates that bind to glycosylated proteins and the use of the lectin affintiy chromatography allows for a protien sample to be enriched in glycosylated proteins. In some embodiments, the method further comrpises performes polyacrylamide gel electrophoresis or mass spectromety (e.g., MALDI-TOF mas spectrometry) on the separated glycosylated enriched protein sample. For example, pancreatic cancer serum can be analyzed using sialic acid specific lectin affintiy chromatography followed by fractionation using RP-HPLC and further separation by SDS-PAGE to idnetify serum marker proteins of pancreatic ancer. The expression of sialic acid glycoproteins with different sub-structures can be compared between normal and cancer serum based on UV absorption detection. Altered glycoproteins can be digested and identified by LC-MS?MS. The structures of released carbohydrte from purified serum proteins can be studies using MALDI mas spectrometry. The method can be sued to detect the change of the isoforms and extend of glycosylation of target glycoproteins in cancer serum. 

In the case of glycoportines, glycan structure often changes in association with disease. The fact that these aberrant glycans can also be immunogenic has been exploited by pathologists in detecting cancer Trhough the use of fluorescently labeled glycan-directed antibodies, staining procedures have been developed that allow differentiation between noraml and malignant cells in tissues on the basis of targeting aberrant glycosylation. In addition, surface glycoproteins are well documented to play a prominent role in the loss of cellular adhesion, metastasis the binding of tumor cells at remote sites and secondary tumor colonization. Regnier (US8,568,993)