title: Surfactant-mediated amyloidogenesis behavior of stem bromelain; a biophysical insight.
abstract: Neurodegenerative disorders are mainly associated with amyloid fibril formation of different proteins. Stem bromelain (SB), a cysteine protease, is known to exist as a molten globule state at pH 10.0. It passes through the identical surrounding (pH 10.0) in the gut epithelium of intestine upon oral administration. Protein-surfactant complexes are widely employed as drug carriers, so the nature of surfactant toward protein is of great interest. The present work describes the effect of cationic surfactants (CTAB & DTAB) and their hydrophobic behavior toward amyloidogenesis behavior of SB at pH 10.0. Multiple approaches including light scattering, far UV-CD, turbidity measurements, and dye binding assay (ThT, Congo red and ANS) were performed to measure the aggregation propensity of SB. Further, we monitored the hydrodynamic radii of aggregates formed using dynamic light scattering technique. Structure of fibrils was also visualized through fluorescence microscopy as well as TEM. At pH 10.0, low concentration of CTAB (0-200 μM) induced amyloid formation in SB as evident from a prominent increase in turbidity and light scattering, gain in β-sheet content, and enhanced ThT fluorescence intensity. However, further increase in CTAB concentration suppressed the fibrillation phenomenon. In contrast, DTAB did not induce fibril formation at any concentration used (0-500 μM) due to lower hydrophobicity. Net negative charge developed on protein at high pH (10.0) might have facilitated amyloid formation at low concentration of cationic surfactant (CTAB) due to electrostatic and hydrophobic interactions.
authors.affiliation: a Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh , UP 202002 , India.
authors.forename: Masihuz
authors.initials: M
authors.lastname: Zaman
authors.affiliation: a Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh , UP 202002 , India.
authors.forename: Syed Mohammad
authors.initials: SM
authors.lastname: Zakariya
authors.affiliation: a Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh , UP 202002 , India.
authors.forename: Saima
authors.initials: S
authors.lastname: Nusrat
authors.affiliation: a Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh , UP 202002 , India.
authors.forename: Mohsin Vahid
authors.initials: MV
authors.lastname: Khan
authors.affiliation: a Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh , UP 202002 , India.
authors.forename: Atiyatul
authors.initials: A
authors.lastname: Qadeer
authors.affiliation: a Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh , UP 202002 , India.
authors.forename: Mohammad Rehan
authors.initials: MR
authors.lastname: Ajmal
authors.affiliation: a Interdisciplinary Biotechnology Unit , Aligarh Muslim University , Aligarh , UP 202002 , India.
authors.forename: Rizwan Hasan
authors.initials: RH
authors.lastname: Khan
mesh_terms: D000682:Amyloid / Q000737:chemistry* / Q000648:ultrastructure; D000817:Anilino Naphthalenesulfonates / Q000737:chemistry; D052160:Benzothiazoles; D001963:Bromelains / Q000737:chemistry*; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry; D003224:Congo Red / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D066329:Protein Aggregates; D011485:Protein Binding; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D055672:Static Electricity; D013501:Surface-Active Agents / Q000737:chemistry*; D013844:Thiazoles / Q000737:chemistry
chemical_list: D000682:Amyloid; D000817:Anilino Naphthalenesulfonates; D052160:Benzothiazoles; D002593:Cetrimonium Compounds; D004396:Coloring Agents; D066329:Protein Aggregates; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D013844:Thiazoles; C013912:decyltrimethylammonium; C009462:thioflavin T; D003224:Congo Red; C027132:1-anilino-8-naphthalenesulfonate; D001963:Bromelains; C091760:stem bromelain; D000077286:Cetrimonium
keywords: CTAB; DTAB; amyloid formation; stem bromelain