Simplified purification approach of urinary neutrophil gelatinase-associated lipocalin by tangential flow filtration and ion exchange chromatography

A simple scheme for large scale purification of urine - Derived Bence Jones Kappa protein

We have investigated and optimized purification process, suitable for industrial scale, to obtain high purity grade Bence Jones Kappa Protein ('BJK-Protein'), while preserving its physiological properties and functions. BJK-Protein was obtained from a biological waste product i.e. human urine of renal failure patients. Isolated 'BJK-Protein' was analyzed by electrophoresis, western blotting, double immunodiffusion, SEC-HPLC assay and Mass Spectrometry (MS). The relative molecular mass of 'BJK-Protein' is 23054.2 Da. Moreover, dimer forms of 'BJK-Protein' were also detected in SDS-PAGE and mass spectrum corresponding to 46054.4 Da. The results of western blotting, immunoelectrophoresis, SEC-HPLC assay, and mass spectrometry analysis indicate a high purity (>99 %) of 'BJK-Protein'. Peptide mass fingerprint analysis of 'BJK-Protein' yielded peptides that partially matches the known database sequences of kappa variable region (KV139_HUMAN) of immunoglobulin. This protein was found to be stable up to 20 months at 2-8 °C temperature and also found negative for major undesirable viral markers as well as bacterial endotoxin. With this purification approach, the cost of purified 'BJK-Protein' is significantly reduced as compared to the current market price of Kappa light chain available in international market.

An improved protocol for large scale production of high purity 'Fc' fragment of human immunoglobulin G (IgG-Fc)

We describe a simplified approach for purification and characterization of human 'IgG-Fc' fragment used widely as immunochemical tool and for therapeutic purposes. The 'Fc' fragment was purified from human IgG in a 3-stage column chromatography. The purified 'Fc' fragment appeared as a dimer glycoprotein with an apparent molecular mass of 52,981 Dalton (Ultraflex MALDI TOF/TOF). The Size-exclusion HPLC profile of the purified 'Fc' fragment of human IgG matched that of a commercially procured reference 'Fc' fragment material. The purity of the 'Fc' fragments was >99% by SDS-PAGE and size-exclusion HPLC. The results of Western blotting, immunoelectrophoresis, and mass spectrometry analysis indicate a high purity of the 'Fc' fragment. Peptide mass fingerprint analysis of the purified 'Fc' protein yielded peptides that partially match the known database sequences of FCG3B_HUMAN (Uniprot ID: O75015). This method of purification of the 'Fc' fragment is suitable for achieving high purity level of 'Fc' fragment protein. With this purification approach, the cost of the purified 'Fc' fragment of human IgG is significantly reduced as compared with the current market price of IgG-Fc fragment protein in international market. The purified 'IgG-Fc' fragment protein was found to be negative for major viral markers.

A cost-effective method for purification and characterization of human urinary albumin

We describe a simplified approach for the purification and characterization of urinary albumin, a key biomarker currently used for understanding the onset and prognosis of microalbuminuria. Urinary albumin was purified from human urine collected from diabetic kidney disease patients by using 2-stage tangential flow filtration process and set of column chromatography steps. The relative molecular mass of urinary albumin is 66,871 Da (SYNAPT G2 High Definition Mass Spectrometry System). Isolated urinary albumin was analyzed by SDS-PAGE, Western blotting, immunoelectrophoresis, Ouchterlony double-immunodiffusion, single radial immunodiffusion, size-exclusion HPLC and peptide mass fingerprint analysis. The size-exclusion HPLC elution profile of the purified urinary albumin was similar to that of a reference form of native albumin. Peptide mass fingerprint analysis of the purified urinary albumin yielded peptides that partially matched with known sequence of ALBU_HUMAN (P02768). This is the first report of purification and validation of immunochemically reactive form of urinary albumin from a large volume of urine of diabetic kidney disease patients. In this purification approach, the cost of the purified albumin is significantly lower.

N-Glycosylation of Lipocalin 2 Is Not Required for Secretion or Exosome Targeting

Lipocalin 2 (LCN2) is a highly conserved secreted adipokine acting as a serum transport protein for small hydrophobic molecules such as fatty acids and steroids. In addition, LCN2 limits bacterial growth by sequestering iron-containing siderophores and further protects against intestinal inflammation and tumorigenesis associated with alterations in the microbiota. Human LCN2 contains one N-glycosylation site conserved in other species. It was postulated that this post-translational modification could facilitate protein folding, protects from proteolysis, is required for proper trafficking from the Golgi apparatus to the cell surface, and might be relevant for effective secretion. We here show that the homologous nucleoside antibiotic tunicamycin blocks N-linked glycosylation but not secretion of LCN2 in primary murine hepatocytes, derivatives thereof, human lung carcinoma cell line A549, and human prostate cancer cell line PC-3. Moreover, both the glycosylated and the non-glycosylated LCN2 variants are equally targeted to exosomes, demonstrating that this post-translational modification is not necessary for proper trafficking of LCN2 into these membranous extracellular vesicles. Furthermore, a hydrophobic cluster analysis revealed that the N-glycosylation site is embedded in a highly hydrophobic evolutionarily conserved surrounding. In sum, our data indicate that the N-glycosylation of LCN2 is not required for proper secretion and exosome cargo recruitment in different cell types, but might be relevant to increase overall solubility.