Proteomic analysis to identify candidate biomarkers associated with type 1 diabetes.

PURPOSE: Type 1 diabetes mellitus (DM1) is one of the most common chronic diseases observed during childhood. The incidence of DM1 is increasing worldwide, and there is currently no way to prevent or delay the onset or to cure the disease. Most diseases, including diabetes, stem from abnormalities in the functioning of proteins, and some studies have reported the expression of protein variation to be involved in the development of DM1. Thus, the aim of this study was to investigate the differential expression of serum proteins in patients with DM1. MATERIALS AND METHODS: Serum of patients with DM1 (n=30) and healthy controls (n=30) was collected. A proteomic approach was used with depletion of albumin and immunoglobulin G chromatography on serum samples followed by data-independent, label-free mass spectrometric analysis. RESULTS: A total of eight serum proteins were identified as being differentially expressed and involved in the immune system, lipid metabolism, and pathways of coagulation. DM1 was associated with the upregulation of six proteins: alpha-2-macroglobulin, apolipoprotein A-II, ß2 glycoprotein I, Ig alpha-2 chain C region, alpha-1-microglobulin, and prothrombin. A total of two proteins were downregulated, including pregnancy zone protein and complement C4. CONCLUSION: To the best of our knowledge, these findings show differential expression of proteins revealing new proteins that may be involved in the development and progression of diabetes.

Crystallization and preliminary X-ray diffraction studies of frutalin, an α-D-galactose-specific lectin from Artocarpus incisa seeds.

Frutalin is an α-D-galactose-specific carbohydrate-binding glycoprotein with antitumour properties and is a powerful tool for tumour biomarker discovery. The crystallization and preliminary X-ray diffraction analysis of this lectin, which was isolated from Artocarpus incisa seeds, are reported here. Frutalin was purified and submitted to mass-spectrometric analysis. Diverse masses at approximately 16 kDa were observed in the deconvoluted spectra, which support the presence of isoforms. The best frutalin crystals were grown within a week in 0.1 M citric acid pH 3.5 which contained 25% PEG 3350 as a precipitant at 293 K, and diffracted to a maximum resolution of 1.81 Å. The monoclinic crystals belonged to space group I2, with unit-cell parameters a = 76.17, b = 74.56, c = 118.98 Å, ß = 96.56°. A molecular-replacement solution was obtained which indicated the presence of four monomers per asymmetric unit. Crystallographic refinement of the structure is in progress.