Closer look helps experts ponder when a protein's prone to wander
University chemists find surface interactions could be tunable at the single-protein level

Date:
March 7, 2022
Source:
Rice University
Summary:
Using sophisticated microscopy techniques, researchers show why
proteins stick better to some surfaces than others. The details
could be important to manufacturers fine-tuning drug purifications,
biosensors or anti- fouling surfaces.



FULL STORY ==========================================================================
A surface that feels smooth to human touch could be pretty rough to
a protein.

That can be good or bad, depending on what you want that protein to do.


========================================================================== Exactly how proteins interact with solid surfaces is a concern for
health care manufacturers who design drugs, make biosensors or develop anti-fouling materials.

The mechanisms that control these interactions are hard to see, but
researchers at Rice University are changing that with a microscopy
technique to assess the effects of surface roughness as well as
water-repelling properties (hydrophobicity) and electrostatic charge. The ability to tune those parameters will lead to more predictable materials.

"The main idea is to understand the how the combination of these
properties influences protein dynamics," said Anastasiia Misiura, lead
author of a study in the Journal of Chemical Physics and a graduate
student in the Rice lab of chemist Christy Landes. "It turned out that roughness and hydrophobicity are opposite forces, but proteins get
stuck on areas that are very rough." The paper, an "editor's choice,"
is part of the journal's "Ever-Expanding Optics of Single Molecules and Nanoparticles" collection.

How molecules interact at surfaces is important at every scale in the
physical realm, from grinding planetary plates to brakes grabbing the
wheels in your car to the invisible molecular transactions that make
life possible. Understanding these mechanisms at the very smallest level
is the focus of Landes' lab as its members attempt to clarify what's
actually happening down there.



==========================================================================
To that end, the lab develops sophisticated microscopes that see things
smaller than visible light and the best of lenses will allow. In this
case, the lab used single molecule fluorescence microscopy, a technique
that allows them to watch how proteins interact with the surfaces
they design.

The team discovered two modes of transport that influence whether and how proteins attach themselves to a surface, travel along it or release their
grip, never to return. The two distinct interaction mechanisms they found ranged from the quicker localized adsorption/desorption, associated with
less hydrophobic surfaces, and an unpredictable continuous-time random
walk observed in interactions with rough, more hydrophobic surfaces.

For experiments, the researcher placed a "well-studied model protein," fluorescent-labeled a-lactalbumin, on a surface with bare glass
alternating with stripes in various concentrations of a self-assembled monolayer (SAM) commonly used to purify proteins via chromatography. Each stripe contained a different balance between hydrophobicity and surface roughness.

The bare glass showed plenty of localized action with proteins taking
a longer time on the surface, while the degree of roughness in the
SAM-covered regions (due to the concentration of octadecyltrichlorosilane,
or ODTS) promoted longer flights. The degree of "stickiness" is associated
with a greater concentration of long alkyl chains on the surface.

Understanding how to tailor surfaces could give manufacturers a handle
to fine- tune protein interactions in their products, Landes said.

"Because all these complicated things are happening at different time
scales and space scales, you could never separate the mechanistic
contributions of each one of those individual effects," she said. "The
real value of single molecule spectroscopy and measuring at these
scales is that you can distinguish the separate contributing factors." Co-authors are Rice postdoctoral researcher Chayan Dutta, graduate
students Wesley Leung, Jorge Zepeda O and research scientist Tanguy
Terlier. Landes is the Kenneth S. Pitzer Schlumberger Chair at Rice
and a professor of chemistry, electrical and computer engineering and
chemical and biomolecular engineering.

The Welch Foundation (C-1787) and the National Science Foundation
(1808382, 1626418) supported the research.

========================================================================== Story Source: Materials provided by Rice_University. Original written
by Mike Williams. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Anastasiia Misiura, Chayan Dutta, Wesley Leung, Jorge Zepeda O,
Tanguy
Terlier, Christy F. Landes. The competing influence of surface
roughness, hydrophobicity, and electrostatics on protein dynamics
on a self- assembled monolayer. The Journal of Chemical Physics,
2022; 156 (9): 094707 DOI: 10.1063/5.0078797 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220307082320.htm

--- up 1 week, 10 hours, 51 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)