Design of hybrid hydrogels using coiled coil motif

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Dec 12, 2012 (4 years and 4 months ago)

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The coiled coils in the design of protein
-
based
constructs:

hybrid hydrogels and epitope displays

Aijun Tang
a

, Chun Wang
b
, Russell J. Stewart
b
, Jindrich Kopecek
a

,
b*


a
Department of Pharmaceutics and Pharmaceutical Chemistry
, 30
S
2000
E Rm
.
301,
University of Utah
,
Salt Lake City
,
UT
84112,

USA

b
Department of Bioengineering
, 20
S
2030
E Rm
. 205,
University of Utah
,
Salt Lake City
,
UT
84112,
USA


Published in Journal of Controlled Release 72(2001)

Introduction

Protein
-
based biomaterials and biomaterials with Proteins have
been attracting more attention recently

Protein polymers contain mixtures of molecules with different
chain length, lack of control of genetic engineering and chain
architecture

Genetic Engineering made possible to produce peptide/protein
with well defined amino acid sequence and precisely controlled
macromolecular architectures including size, composition,
sequence


Introduction

Genetic
Engineering

Plasmid
Technology

Engineered protein with
non natural function

Produce new protein with
predetermined properties

Conjugation of Polymer with
genetically engineered site of
protein for wide range purposes

Coiled Coils

A coiled coil is a bundle of two or more right
-
handed
amphiphilic a
-
helices wrapping around each other into a
slightly left
-
handed super
-
helix (Fig. 1A).


Consists of heptad repeats[(abcdefg)x]


a,d positions occupied by hydrophobic residues


The other positions usually occupied by polar ones


Hydrophobic interaction stabilizing the coiled coil
conformation

Heterodimeric coiled coil used in biosensor and affinity
purification

Coiled Coils

Parallel and
antiparallel
determined by
electrostatic
interaction between
residues e and g

Affinity matrix for
protein purification &
Biosensor Application

Multivalent

Antibody

Conformationally
defined synthetic
lybray

Self replicating peptide

Coiled Coils

Design of hybrid hydrogels using coiled coil motif


Hydrogels are 3D polymer network that do not dissolve in water
but are able to swell and retain significant amount of water, used
in surgical sutures, soft tissue prostheses, drug delivery system,
soft contact lenses

Old Tech
Hydrogel

Lack exast control on 3D structure

Heterogeneity in structure and
physicochemical properties

Hybrid hydrogel : hydrogel system contained two
or more components of dinstinct classes of
molecules

Design of hybrid hydrogels using coiled coil motif


Advantages of Hybrid hydrogel

We can combined good properties from different
components to achieve a better one, example :
assembling Hybrid hydrogel from synthetic polymers and
Genetically engineered protein

It maybe possible to create HH that are responsive to a
variety of stimuly such as ph, ionic strength, solvent, light,
mechanical force, and specific ligand

Design of hybrid hydrogels using coiled coil motif


T increase

Design of an epitope display system using

coiled coil motif


An
epitope

is the part of a
macromolecule

that is recognized by the
immune system
, specifically by
antibodies
,
B cells
, or
cytotoxic T
cells
.

Small synthetic epitopes may represent a new category of
targetting moieties for polymer based targettable drug delivery
systems, but the problem is we need to find structure
biorecognition relationship to achieve best targetting ability

Biomolecules

Application

Biosensing

Affinity Separation

Generating surfaces with specific
biocompatibility

Design of an epitope display system using

coiled coil motif


Immobilization
Technique

Physical Adsorption

Covalent Binding

Langmuir
-
Blodgett tech (LB) : popular for ordered monolayers of
amphipiles


SAM

Alkanethiolate SAMs

Alkyl Siloxane SAMs

Design of an epitope display system using

coiled coil motif


Biorecognition sites in proteins are often presented on the
surfaces with the whole molecules serving as conformational
scaffolds. To mimic natural proteins, protein/peptide construsts,
such as coiled coil peptides, can be designed de novo and used a
sequence simplified scaffolds into which recognition elements
from naturally occuring proteins and peptides can be incorporated

Conclusions


Applying genetic engineering techniques to biomaterials and
drug delivery research offers numerous opportunities of creating
protein based constructs with well
-
defined structure and unique
properties



Genetically engineered CCP motifs were used to form crosslinks
of HH responsive to external stimuli



Self Assembly CC stem loop constructs were prepared for
studying the biorecognition between ligands and cell surface
reseptors



This approaches will lead to the development of intelligent drug
delivery/release systems and will provide new insight for the
rational design of more effective targetable drug carriers



THANK YOU