title: α-Lactalbumin nanoparticles prepared by desolvation and cross-linking: structure and stability of the assembled protein.
abstract: A key step in the preparation of cross-linked protein nanoparticles involves the desolvation of proteins with an organic solvent, which is thought to act by modulating hydrophobic interactions. However, to date, no study has examined the conformational changes that proteins undergo during the assembly process. In this work, by using several biophysical techniques (CD spectroscopy, DSC, TEM, etc.), we studied spheroidal nanoparticles made from bovine α-lactalbumin cross-linked with glutaraldehyde in the presence of acetone. Within the nanoparticle, the polypeptide chain acquires a β-strand-like conformation (completely different from the native protein in secondary and tertiary structure) in which several side chains likely become available for reacting with glutaraldehyde. A multiplicity of cross-linking sites, together with the polymeric nature of glutaraldehyde, may thus explain the low dry-weight fraction of protein that was found in the nanoparticles. Although covalent bonds undoubtedly constitute the main source for nanoparticle stability, noncovalent interactions also appear to play a role in this regard.
authors.affiliation: Department of Food Science, University of Massachusetts, Amherst, MA 01003, USA; Área de Biofisicoquímica, Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Apartado Postal 55-534, Iztapalapa, D.F. 09340, Mexico. Electronic address: iarroyo@foodsci.umass.edu.
authors.forename: Izlia J
authors.initials: IJ
authors.lastname: Arroyo-Maya
authors.affiliation: Departamento de Graduados e Investigación en Alimentos, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Carpio y Plan de Ayala, Miguel Hidalgo, D.F. 11340, Mexico.
authors.forename: Humberto
authors.initials: H
authors.lastname: Hernández-Sánchez
authors.affiliation: Departamento de Graduados e Investigación en Alimentos, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Carpio y Plan de Ayala, Miguel Hidalgo, D.F. 11340, Mexico.
authors.forename: Esmeralda
authors.initials: E
authors.lastname: Jiménez-Cruz
authors.affiliation: Área de Biofisicoquímica, Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Apartado Postal 55-534, Iztapalapa, D.F. 09340, Mexico.
authors.forename: Menandro
authors.initials: M
authors.lastname: Camarillo-Cadena
authors.affiliation: Área de Biofisicoquímica, Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Apartado Postal 55-534, Iztapalapa, D.F. 09340, Mexico. Electronic address: aha@xanum.uam.mx.
authors.forename: Andrés
authors.initials: A
authors.lastname: Hernández-Arana
mesh_terms: D000818:Animals; D002417:Cattle; D003432:Cross-Linking Reagents / Q000737:chemistry*; D005976:Glutaral / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007768:Lactalbumin / Q000737:chemistry* / Q000302:isolation & purification; D008892:Milk / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D017510:Protein Folding; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D003432:Cross-Linking Reagents; D007768:Lactalbumin; D005976:Glutaral
keywords: Circular dichroism; Differential scanning calorimetry; Nanoparticles; Secondary structure; α-Lactalbumin