Complex Formation of Protein with Different Water-Soluble Synthetic Polymers
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- 作者：Toshiyuki Matsudo ; Kazuyoshi Ogawa ; and Etsuo Kokufuta
- 刊名：Biomacromolecules
- 出版年：2003
- 出版时间：November 2003
- 年：2003
- 卷：4
- 期：6
- 页码：1794 - 1799
- 全文大小：147K
- 年卷期：v.4,no.6(November 2003)
- ISSN：1526-4602
文摘
The formation of protein-polymer complexes was studied in an aqueous system using dynamic light scattering(DLS) and static light scattering (SLS) as the main experimental tools. Human serum albumin (HSA) wasused as a protein and complexed with four representative water-soluble polymers: poly(N-isopropylacrylamide) (PNIPA), poly(ethylene glycol) (PEG), poly(vinyl pyrrolidone) (PVP), and poly(vinyl alcohol)(PVA). The first three molecular weights were within 420,000-540,000 and the last one was 270,000. Thecomplexation was performed at 25 
C in 0.01 M NaCl solution adjusted to pH 3 with HCl as a function ofmixing ratio (rm; molar ratio of polymer to HSA). From SLS experiments, we determined the molecularweight of the resulting complexes, from the value of which the number (nb) of bound proteins per polymerwas estimated. It was found that each polymer forms an intrapolymer complex over a wide range of rm(1.2 
rm 0.01). Then, a marked decrease in nb with increasing rm was found. Over the whole rm range,the HSA-PNIPA complex exhibited a large nb value, as compared with the other three complexes whosenb values at the same rm were close to one another. Both the hydrodynamic radius (Rh) by DLS and theradius of gyration (Rg) by SLS for the complexes of PNIPA, PVP, and PVA decreased and then reached aconstant value as nb decreased with increasing rm. In the PEG system, however, there were a few changesin Rh and Rg with nb. The Rg/Rh ratio, as an indication of chain expansion, was found to increase withdecreasing nb in the PNIPA system. The complexes of PVA and PVP displayed a similar tendency, althoughthe magnitude of the increasing trend was smaller than that of the PNIPA complex. In contrast, the Rg/Rhratio of the PEG complex hardly varied depending on nb. These results were discussed in connection withthe differences of physicochemical properties among four water-soluble polymers.
C in 0.01 M NaCl solution adjusted to pH 3 with HCl as a function ofmixing ratio (rm; molar ratio of polymer to HSA). From SLS experiments, we determined the molecularweight of the resulting complexes, from the value of which the number (nb) of bound proteins per polymerwas estimated. It was found that each polymer forms an intrapolymer complex over a wide range of rm(1.2 rm 0.01). Then, a marked decrease in nb with increasing rm was found. Over the whole rm range,the HSA-PNIPA complex exhibited a large nb value, as compared with the other three complexes whosenb values at the same rm were close to one another. Both the hydrodynamic radius (Rh) by DLS and theradius of gyration (Rg) by SLS for the complexes of PNIPA, PVP, and PVA decreased and then reached aconstant value as nb decreased with increasing rm. In the PEG system, however, there were a few changesin Rh and Rg with nb. The Rg/Rh ratio, as an indication of chain expansion, was found to increase withdecreasing nb in the PNIPA system. The complexes of PVA and PVP displayed a similar tendency, althoughthe magnitude of the increasing trend was smaller than that of the PNIPA complex. In contrast, the Rg/Rhratio of the PEG complex hardly varied depending on nb. These results were discussed in connection withthe differences of physicochemical properties among four water-soluble polymers.