title: Structure-function studies of Murraya koenigii trypsin inhibitor revealed a stable core beta sheet structure surrounded by alpha-helices with a possible role for alpha-helix in inhibitory function.
abstract: Structure-function studies of Murraya koenigii trypsin inhibitor revealed a compact structure made of central beta-sheet surrounded by alpha-helices with differences in structure and functional stability. Proteolysis studies, of native and heat-treated protein, demonstrated that inhibitor exhibited strong resistance to proteolysis by many proteases. However, the inhibitory activity gradually decreased with increasing temperature and was completely lost at 90 degrees C. CD studies, under native conditions, showed that inhibitor contains approximately 46% beta-strand, 30.1% alpha-helical, 16.2% turn and 6.9% random coil structure. At increasing temperatures, however, helix to coil transition was observed. The ANS fluorescence study showed linear increase of fluorescence intensity without showing any melting transition. Correlating decrease in inhibitory activity and helical content at increasing temperatures suggest a possible role for alpha-helical structure in inhibitory function of the protein.
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India.
authors.forename: Chandan
authors.initials: C
authors.lastname: Shee
authors.forename: Asimul
authors.initials: A
authors.lastname: Islam
authors.forename: Faizan
authors.initials: F
authors.lastname: Ahmad
authors.forename: Ashwani K
authors.initials: AK
authors.lastname: Sharma
mesh_terms: D000817:Anilino Naphthalenesulfonates / Q000378:metabolism; D002942:Circular Dichroism; D004795:Enzyme Stability; D005456:Fluorescent Dyes / Q000378:metabolism; D006358:Hot Temperature; D006868:Hydrolysis; D032101:Murraya / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship; D014361:Trypsin Inhibitors / Q000737:chemistry*
chemical_list: D000817:Anilino Naphthalenesulfonates; D005456:Fluorescent Dyes; D014361:Trypsin Inhibitors