Skip to main content
Journal cover image

Multilayer adsorption of lysozyme on a hydrophobic substrate.

Publication ,  Journal Article
Schmidt, CF; Zimmermann, RM; Gaub, HE
Published in: Biophysical journal
March 1990

Macromolecular adsorption is known to occur as a complex process, often in a series of steps. Several models are discussed in the literature which describe the microscopic structure of the adsorbate. In the present study we investigated the adsorption of hen egg white lysozyme on alkylated silicon oxide surfaces. A combination of fluorescence excitation in the evanescent field and fluorescence recovery after photobleaching allowed us to measure the amount of adsorbed fluorescent lysozyme and the equilibrium exchange kinetics with molecules in solution. We found that a model with at least three classes of adsorbed molecules is necessary to describe the experimental results. A first layer is formed by the molecules which adsorb within a short time after the beginning of the incubation. These molecules make up approximately 65% of the final coverage. They are quasi-irreversibly adsorbed and do not measurably exchange with bulk molecules within one day even at temperatures up to 55 degrees C. A second layer, which reaches equilibrium only after several hours of incubation, shows a pronounced exchange with bulk molecules. The on-off kinetics show a distinct temperature dependence from which an activation barrier of delta E approximately 22 kcal/mol is derived. A third layer of molecules that exchange rapidly with the bulk can be seen to comprise approximately 10% of the total coverage. The exchange rate is on the order of fractions of a second. The binding of the latter two classes of adsorbed molecules is exothermic. From the temperature dependence of the coverage, the binding enthalpy of the slowly exchanging layer was estimated to be delta Hads approximately 3.8 kcal/mol. The second and third class of molecules remain enzymatically active as a muramidase, which was tested by the lysis of the cell walls of Micrococcus lysodeiktikus. The molecules in the first layer, on the other hand, showed no enzymatic activity.

Duke Scholars

Published In

Biophysical journal

DOI

EISSN

1542-0086

ISSN

0006-3495

Publication Date

March 1990

Volume

57

Issue

3

Start / End Page

577 / 588

Related Subject Headings

  • Thermodynamics
  • Protein Denaturation
  • Muramidase
  • Microscopy, Fluorescence
  • Mathematics
  • Kinetics
  • Hot Temperature
  • Biophysics
  • Adsorption
  • 51 Physical sciences
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Schmidt, C. F., Zimmermann, R. M., & Gaub, H. E. (1990). Multilayer adsorption of lysozyme on a hydrophobic substrate. Biophysical Journal, 57(3), 577–588. https://doi.org/10.1016/s0006-3495(90)82573-x
Schmidt, C. F., R. M. Zimmermann, and H. E. Gaub. “Multilayer adsorption of lysozyme on a hydrophobic substrate.Biophysical Journal 57, no. 3 (March 1990): 577–88. https://doi.org/10.1016/s0006-3495(90)82573-x.
Schmidt CF, Zimmermann RM, Gaub HE. Multilayer adsorption of lysozyme on a hydrophobic substrate. Biophysical journal. 1990 Mar;57(3):577–88.
Schmidt, C. F., et al. “Multilayer adsorption of lysozyme on a hydrophobic substrate.Biophysical Journal, vol. 57, no. 3, Mar. 1990, pp. 577–88. Epmc, doi:10.1016/s0006-3495(90)82573-x.
Schmidt CF, Zimmermann RM, Gaub HE. Multilayer adsorption of lysozyme on a hydrophobic substrate. Biophysical journal. 1990 Mar;57(3):577–588.
Journal cover image

Published In

Biophysical journal

DOI

EISSN

1542-0086

ISSN

0006-3495

Publication Date

March 1990

Volume

57

Issue

3

Start / End Page

577 / 588

Related Subject Headings

  • Thermodynamics
  • Protein Denaturation
  • Muramidase
  • Microscopy, Fluorescence
  • Mathematics
  • Kinetics
  • Hot Temperature
  • Biophysics
  • Adsorption
  • 51 Physical sciences