BIOPHYSICAL THEORY AND MODELING |
Mean-field model of immobilized enzymes embedded in grafted polymer layer
Yevgeny Moskovitz 1 and Simcha Srebnik 1*
1 Technion - Israel Institute of Technology
* To whom correspondence should be addressed. E-mail: simchas{at}tx.technion.ac.il.
Submitted on September 27, 2004
Revised on November 7, 2004
Accepted on 21 March 2005
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Abstract |
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Two-dimensional mean-field lattice theory is used to model immobilization and stabilization of an enzyme on a hydrophobic surface using grafted polymers. While the enzyme affords biofunctionality, the grafted polymers stabilize the enzyme and impart biocompatibility. The protein is modeled as compact hydrophobic-polar polymer, designed to have a specific bulk conformation reproducing the catalytic cleft of natural enzymes. Three scenarios are modeled that have medical or industrial importance: (1) It is shown that short hydrophilic grafted polymers, such as polyethylene glycol (PEG) that are often used to provide biocompatibility, can also serve to protect a surface-immobilized enzyme from adsorption and denaturation on a hydrophobic surface. (2) Screening of the enzyme from the surface and nonspecific interactions with biomaterial in bulk solution requires a grafted layer composed of short hydrophilic polymers and long triblock copolymers. (3) Hydrophilic polymers grafted on a hydrophobic surface in contact with an organic solvent form a dense hydrophilic nanoenvironment near the surface that effectively shields and stabilizes the enzyme against both surface and solvent.
Key Words:
biopolymers, grafted polymers, mean field theory, protein adsorption
