1995 Fiscal Year Final Research Report Summary
Study on Complexation of Proteins with Polyelectrolytes
| Project/Area Number |
05044077
|
|---|
| Research Category |
Grant-in-Aid for international Scientific Research
|
| Allocation Type | Single-year Grants |
|---|
| Section | Joint Research |
|---|
| Research Institution | University of Tsukuba |
|---|
Principal Investigator |
KOKUFUTA Etsuo Institute of Applied Biochemistry, University of Tsukuba, Professor, 応用生物化学系, 教授 (40124648)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
DAVIS Richey M. Department of Engineering, VirginiaPolytechnic Institute and State University, A, 助教授
MUHOBERAC Ba Iupul, Dept・of chem., 準教授
DUBIN Paul L. Department of Chemistry, IUPUI,Professor, Dept・of chem., 教授
HIRATA Mitsuo College of Industrial Technology, Nihon University, Professor, 生産工学部, 教授 (00059768)
BARRY B.Muhoberac Department of Chemistry, IUPUI,Associate Professor
|
|---|
| Project Period (FY) |
1993 – 1995
|
| Keywords | Proteins / Polyelectrolytes / Complexation / Turbidimetric titration / Quasi-elastic light scattering / Electrophoretic light scattering / Enzymatic activity / Separation technology |
|---|
| Research Abstract |
The complexation of proteins with natural and synthetic polyelectrolytes in an aqueous system in interesting from two points of view. The first concerns the way in which the polymers interact with non-flexible protein molecules, an understanding of which could provide a better explanation of the mechanisms of macromolecular interaction available in nature. The second concerns the extent to which biochemical activity is maintained in the resulting complexes, the answer to which is central to the molecular design of composite protein-polymer systems, such as immobilized enzymes, as well as the design of protein separation processes using water-soluble polymers.
The present study has dealt with the formation of protein-polyelectrolyte complexes (PPCs) under different conditions of pH and salt concentration. Turbidimetric titration, quasi-elastic light scattering (QELS), static light scattering (SLS), electrophoretic light scattering (ELS) and fluorescence spectroscopy have been employed. I
… More
n addition, biochemical methods such as the measurement of enzymatic activity have also been employed in the appropriate cases. The main conclusions derived from these previous studies may be summarized as follows : (i) PPCs are formed mainly through electrostatic forces ; (ii) in salt-free systems, at least, protein molecules are complexed with flexible polyelectrolytes through 1 : 1 stoichiometric formation of ion pairs (or salt linkages) between oppositely charged groups ; (iii) the ion pairs between the polyelectrolyte and protein molecules are very weak, some of these bindings severed by changes in pH and the addition of small ions and polyions ; and (iv) there is an appreciable retention of biochemical function in theresultant complexes ; therefore, changes in the three-dimensional conformations of the protein molecules caused by complexation are not so large as to cause a loss of original functions.
From the above results the processes of PPC formation may be inferred as follows : At first, many protein molecules are bound to one polyion to form an intrapolymer complex ; especially in salt-free systems, all of its polyion charges are stoichiometrically neutralized by the opposite charges of the proteins. After this, the resultant intrapolymer complexes interact with one another, yielding aggregates or coacervates. It appears likely that such an intrapolymer PPC consists of a number of protein molecules bridged or bundled together by one extended polyelectrolyte ion. The salt linkages maintaining the structure of the intrapolymer PPC seem to be very loose, because changes in pH or additions of other polyions sever some of the salt linkages. This looseness may make it possible for the protein and polyion molecules to undergo stoichiometric neutralization with oppositely charged groups through thermal motion. Less
|
Research Products
(16 results)
