title: Interaction of an intermediate structure of Bacillus subtilis alpha-amylase with alkyl-substituted sepharose 4B: a model of membrane translocation.
abstract: An intermediate form of alpha-amylase from Bacillus subtilis was prepared following a previously reported procedure. Stabilization of this protein structure by various additives and its interaction with alkyl-substituted Sepharose 4B (Sepharose-lipid), used to mimic the role of the alkyl chains of the phospholipid bilayer, were investigated. Exposure of hydrophobic clusters in the protein structure on denaturation was indicated by a greater affinity of the intermediate form for interaction with the alkyl chains on the matrix, as compared with the original native structure. Near- and far-ultraviolet circular dichroism studies supported loss of tertiary structure with retention of secondary structure, as expected from molten globular intermediate forms. Based on the results presented, we suggest that interaction of a protein in its native and nonnative forms with an alkyl-substituted matrix may provide useful information regarding its capacity for insertion into and translocation across the biologic membrane.
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, PO Box 13145-1384, Tehran, Iran.
authors.forename: Hamid Reza
authors.initials: HR
authors.lastname: Karbalaei-Heidari
authors.forename: Azadeh Ebrahim
authors.initials: AE
authors.lastname: Habibi
authors.forename: Khosro
authors.initials: K
authors.lastname: Khajeh
authors.forename: Bijan
authors.initials: B
authors.lastname: Ranjbar
authors.forename: Mohsen
authors.initials: M
authors.lastname: Nemat-Gorgani
mesh_terms: D000818:Animals; D001412:Bacillus subtilis / Q000201:enzymology*; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism; D008954:Models, Biological; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012685:Sepharose / Q000737:chemistry* / Q000378:metabolism; D000516:alpha-Amylases / Q000737:chemistry* / Q000378:metabolism
chemical_list: D026901:Membrane Transport Proteins; D012685:Sepharose; D000516:alpha-Amylases