TY - JOUR

T1 - Adsorption of Denaturated Lysozyme at the Air-Water Interface: Structure and Morphology

AU - Campbell, Richard A.

AU - Tummino, Andrea

AU - Varga, Imre

AU - Миляева, Ольга Юрьевна

AU - Крицкий, Михаил Михайлович

AU - Lin, Shi-Yow

AU - Laux, V.

AU - Haertlein, M.

AU - Forsyth, V.T.

AU - Носков, Борис Анатольевич

PY - 2018/5/1

Y1 - 2018/5/1

N2 - The application of protein deuteration and high flux neutron reflectometry has allowed a comparison of the adsorption properties of lysozyme at the air-water interface from dilute solutions in the absence and presence of high concentrations of two strong denaturants: urea and guanidine hydrochloride (GuHCl). The surface excess and adsorption layer thickness were resolved and complemented by images of the mesoscopic lateral morphology from Brewster angle microscopy. It was revealed that the thickness of the adsorption layer in the absence of added denaturants is less than the short axial length of the lysozyme molecule, which indicates deformation of the globules at the interface. Two-dimensional elongated aggregates in the surface layer merge over time to form an extensive network at the approach to steady state. Addition of denaturants in the bulk results in an acceleration of adsorption and an increase of the adsorption layer thickness. These results are attributed to incomplete collapse of the globules in the bulk from the effects of the denaturants as a result of interactions between remote amino acid residues. Both effects may be connected to an increase of the effective total volume of macromolecules due to the changes of their tertiary structure, that is, the formation of molten globules under the influence of urea and the partial unfolding of globules under the influence of GuHCl. In the former case, the increase of globule hydrophobicity leads to cooperative aggregation in the surface layer during adsorption. Unlike in the case of solutions without denaturants, the surface aggregates are short and wormlike, their size does not change with time, and they do not merge to form an extensive network at the approach to steady state. To the best of our knowledge, these are the first observations of cooperative aggregation in lysozyme adsorption layers.

AB - The application of protein deuteration and high flux neutron reflectometry has allowed a comparison of the adsorption properties of lysozyme at the air-water interface from dilute solutions in the absence and presence of high concentrations of two strong denaturants: urea and guanidine hydrochloride (GuHCl). The surface excess and adsorption layer thickness were resolved and complemented by images of the mesoscopic lateral morphology from Brewster angle microscopy. It was revealed that the thickness of the adsorption layer in the absence of added denaturants is less than the short axial length of the lysozyme molecule, which indicates deformation of the globules at the interface. Two-dimensional elongated aggregates in the surface layer merge over time to form an extensive network at the approach to steady state. Addition of denaturants in the bulk results in an acceleration of adsorption and an increase of the adsorption layer thickness. These results are attributed to incomplete collapse of the globules in the bulk from the effects of the denaturants as a result of interactions between remote amino acid residues. Both effects may be connected to an increase of the effective total volume of macromolecules due to the changes of their tertiary structure, that is, the formation of molten globules under the influence of urea and the partial unfolding of globules under the influence of GuHCl. In the former case, the increase of globule hydrophobicity leads to cooperative aggregation in the surface layer during adsorption. Unlike in the case of solutions without denaturants, the surface aggregates are short and wormlike, their size does not change with time, and they do not merge to form an extensive network at the approach to steady state. To the best of our knowledge, these are the first observations of cooperative aggregation in lysozyme adsorption layers.

KW - AIR/WATER INTERFACE

KW - BREWSTER-ANGLE MICROSCOPY

KW - DILATIONAL SURFACE RHEOLOGY

KW - EGG-WHITE LYSOZYME

KW - FLUID INTERFACES

KW - GLOBULAR-PROTEINS

KW - PHASE-TRANSITION

KW - RAY REFLECTIVITY

KW - SERUM-ALBUMIN

KW - X-RAY

UR - http://www.scopus.com/inward/record.url?scp=85046264195&partnerID=8YFLogxK

UR - http://www.mendeley.com/research/adsorption-denaturated-lysozyme-airwater-interface-structure-morphology

U2 - 10.1021/acs.langmuir.8b00545

DO - 10.1021/acs.langmuir.8b00545

M3 - Article

VL - 34

SP - 5020

EP - 5029

JO - Langmuir

JF - Langmuir

SN - 0743-7463

IS - 17

ER -