Anti-His tag antibody

Interferonbeta-1b (IFN beta-1b) developed as therapeutic protein for the treatment of multiple sclerosis (MS). Studies have been shown that Long-term usage of this protein can lead to the development of anti-drug antibodies (ADAs) and this phenomenon cause total loss or reduced efficacy of IFN beta-1b. The aim of this study was to predict and silence IFN beta-1b T-cells epitopes by in silico methods and genetic engineering. Based on bioinformatics studies we identified optimal sets of conservative point mutations for eliminating T-cells epitopes in IFN beta-1b protein. Four synthetic genes with desirable mutation constructed and PET26b+ was used as an expression vector in E. coli. The expression of this proteins confirmed by SDS-PAGE and Western blotting, consequently, IFN beta-1b proteins was purified by His-tag chromatography. To determined activity of mutants' variants anti-proliferative and anti-viral activity compared to wild form was evaluated using MTT assay in A549 and Vero cells lines respectively. Also the immunogenicity of mutant proteins compared with Betaseron measured in BALB/c mice. The in vitro bioactivity analysis demonstrated that functional activities of all mutant proteins were maintained and is the same as biological activity of Betaseron. Pharmacokinetic studies suggest that, in engineered proteins that contain substitution of Histidine to Glutamic Acid at position 131 (mut 2 and mut 1+2) antibodies response reduced by about 50%, as compared to that for Betaseron. Computational analysis expedites identification and prediction of epitopes in therapeutic protein, therefore, we used immunoinformatic tools for modification of dominant T-cell epitope in IFN beta-1b protein, and this strategy has capacity to create proteins which have naturally reduced immunogenicity.

In this work, we studied the effect of the C-terminally attached poly-histidine tag (His-tag), as well as the peculiarities of the protein purification procedure by the immobilized metal affinity chromatography (IMAC) on the activity and structure of the metalloenzyme, L-alanyl-D-glutamate peptidase of bacteriophage T5 (EndoT5), whose zinc binding site and catalytic aspartate are located near the C-terminus. By itself, His-tag did not have a significant effect on either activity or folding of the polypeptide chain, nor on the binding of zinc and calcium ions to the protein. However, the His-tagged EndoT5 samples had low shelf-life, with storage of these samples resulting in an increased propensity for protein self-association and decreased enzymatic activity of EndoT5. Furthermore, disastrous effects on the activity of the enzyme were exerted by the presence of imidazole and nickel ions accompanying metal chelate chromatography. The activity of the protein can be restored by thorough washing off of these low molecular impurities via the prolonged dialysis of the His-tagged EndoT5 samples at the specifically elaborated conditions. (C) 2018 Elsevier B.V. All rights reserved.