Laboratory of Macromolecular Solutions Laboratory of

Macromolecular Solutions

Graduate School of ScienceProfessor

Ken TERAO

kterao

URL: https://www.chem.sci.osaka-u.ac.jp/lab/terao/

Macromolecules in solution can take anearly infinite number of conformations
due to their high degree of freedom ofinternal rotations. Macromolecules insolution have, therefore, specificcharacteristics not found in smallmolecules. Intramolecular interactions ina macromolecule and intermolecularinteractions with solvent molecules
significantly influence the molecularshape in solution. Furthermore, strong
intramolecular interactions, includinghydrogen bonding and electrostaticinteractions, lead to the formation ofmicelles and aggregates. Theintermolecular interactions between
polymers through solvents can also
cause various phase separations. Suchphenomena correlate with the functions
in biosystems. Our research aim is toclarify the various phenomena exhibitedby macromolecules in solution, that is,single chain conformation, complex
formation behavior, and phaseseparation behavior by using the latest
scattering and spectroscopic methods.
Dissociation and association
mechanisms of multiple helicalpolysaccharides
DNA and collagen forming multiple
helical structures express importantfunctions in living organisms. Xanthan isa double helical polysaccharide. It is
widely used for food additives because
the aqueous solution has significantly
high viscosity. Circular dichroism (CD)and small-angle X-ray scattering (SAXS)
measurements were made for xanthan
samples in aqueous NaCl after rapid
temperature change eventually to find anovel specific intermediate structure.

Taking into consideration that mismatchdouble helix can yield hairpin-like andmultibranched structures, investigation ofkinetics of the dissociation and associationmechanisms is important to understand thefunctions of multiple helical polysaccharides inliving organisms as well as food additives.
We thus investigate that novel specificproperties and functions can be added toconventional polysaccharides by controllingthe dissociation and association behavior of
multiple helix formation.

Figure 1. Schematic representation of conformationalchange after rapid heating and cooling processes
and the time constants.

Solution properties of polymers
having cyclic and branchedstructures
Cyclic polymers including plasmids play
important roles in vivo, such as in genetic
expression. Rigid polysaccharide derivatives
were prepared and characterized in terms of theseveral experimental methods to investigate theintermolecular interactions and specificfunctions of cyclic polymers. We found that theinteractions with small molecules wereappreciably different from those forconventional linear chains. Furthermore,
spontaneously folded conformation was foundconcentrated liquid crystalline solutions.
Branched structures are often found in
biopolymers (especially polysaccharides) as in
the case of cyclic structures. We thus study
cyclic polymers as well as branched polymers toexplore unknown physical properties andfunctions.

Figure 2. Schematic representation of the rigid ring
polymer.

Let us discover unknown andinteresting phenomena through theunique ideas and physical properties ofpolymers.

Department of Biological Sciences
Graduate School of Science, Osaka University
1-1, Machikaneyama-cho, Toyonaka, Osaka
560-0043, Japan
TEL: +81-6-6850-5461
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