Synthesis and Glutathione Peroxidase (Gpx)-Like Activity of Selenocystine (sec) Bioconjugates of Biotin and Lipoic Acid.

The conjugation of active biomolecules provides insight into their bioreactivity, leading to many applications in biotechnology and materials science. Herein, we report L-selenocystine (SeC) bioconjugates of lipoic acid (universal antioxidant) and biotin (Vitamin-H). The SeC-bioconjugates, SeC-Biotin (1) and SeC-Lipoic acid (2) were synthesized using solid phase peptide synthesis (SPPS) method and were characterized by multinuclear 1D (1H, 13C, 77Se) and 2D (1H-1H COSY and 1H-13C TOCSY) NMR spectroscopy, ESI–MS spectrometry, and RP-HPLC. The GPx-like enzyme mimicking activity of the SeC-bioconjugates 1 and 2 has been investigated through the coupled reductase assay method for the catalytic reductions of hydrogen peroxide into water. A significant enhancement in GPx-like enzymatic activity was observed for both novel bioconjugates SeC-Biotin (1) and SeC-Lipoic acid (2) as compared to diphenyl diselenide (Ph2Se2), L-selenocystine (SeC), biotin, lipoic acid, and ebselen.