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Abstract: The enzyme myeloperoxidase (MPO) is an important part of the neutrophil immune reaction and can be found in alfa granula. The presence of MPO can be used to distinguish acute myelogenous leukemia from acute lymphocytic leukemia. However, the methods employed to do so, such as flow cytometry and immunohistochemistry rely on antibody recognition, and therefore the characterization of the mature MPO, including post-translational modifications, must be considered as important as epitope mapping. MPO has 5 N-linked glycosylation sites, occupied by both high mannose and complex glycan structures. In this study we utilize intact glycopeptide MSMS analysis for site specific characterization of the glycan structures of MPO from a cancer patient. The identified glycan structures are compared to those of MPO from healthy donors, in order to probe for any potential differences that may have diagnostic use. [ABSTRACT FROM AUTHOR]

Abstract: The vitamin D binding protein, Gc globulin, has in recent years received some attention for its role as precursor for the extremely potent macrophage activating factor (GcMAF). An O-linked trisaccharide has been allocated to the threonine residue at position 420 in two of the three most common isoforms of Gc globulin (Gc1s and Gc1f). A substitution for a lysine residue at position 420 in Gc2 prevents this isoform from being glycosylated at that position. It has been suggested that Gc globulin subjected sequentially to sialidase and galactosidase treatment generates GcMAF in the form of Gc globulin with only a single GalNAc attached to T420. In this study we confirm the location of a linear trisaccharide on T420. Furthermore, we provide the first structural evidence of the generation of the proposed GcMAF by use of glycosidase treatment and mass spectrometry. Additionally the generated GcMAF candidate was tested for its effect on cytokine release from macrophages in human whole blood. [Copyright &y& Elsevier]