Intramolecular Complex Formation of Poly(N-isopropylacrylamide) with Human Serum Albumin
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- 作者：Toshiyuki Matsudo ; Kazuyoshi Ogawa ; and Etsuo Kokufuta
- 刊名：Biomacromolecules
- 出版年：2003
- 出版时间：May 2003
- 年：2003
- 卷：4
- 期：3
- 页码：728 - 735
- 全文大小：178K
- 年卷期：v.4,no.3(May 2003)
- ISSN：1526-4602
文摘
Complexation of human serum albumin (HSA) with poly(N-isopropylacrylamide) (PNIPA) ranging inmolecular weight (
PNIPA) from 2.1 × 104 to 1.72 × 106 was studied in an aqueous system (pH 3) containingNaCl as a supporting salt. Dynamic light scattering, static light scattering, electrophoretic light scattering,and dialyzing techniques were used as the experimental tool in a suitable combination. The measurementswere performed mainly at 25 
C and at 0.01 M NaCl as a function of mixing ratio (rm, molar ratio ofPNIPA to HSA). The results of DLS and ELS evidently demonstrated the formation of a water-solublecomplex through mixing of HSA and PNIPA. A detailed analysis of SLS data with the aid of dialysis datarevealed that the resulting complex is an "intramolecular" complex consisting of a PNIPA chain with severalof bound HSA molecules. Both hydrodynamic radius (Rh) and radius gyration (Rg) of intramolecular complexesdecreased as rm was increased. This result correlated well to the fact that the number (n) of bound proteinsper polymer decreases with increasing rm. The size and the molar mass of the complex became large dependingon PNIPA, but the increase of PNIPA led to a decrease in n at rm < 1. The increase in NaCl concentrationfrom 0.01 to 0.3 M brought about the increase in the size and the molar mass of an intramolecular HSA-PNIPA complex prepared at rm = 1.1. This was found to be due to an increase of n. A similar trend wasobserved when temperature rose from 25 to 32 C (close to lower critical solution temperature of PNIPA).However, the effect of temperature on the increase of was strong in comparison with that of ionic strength.On the basis of these results obtained, the complexation mechanism was discussed in detail.
PNIPA) from 2.1 × 104 to 1.72 × 106 was studied in an aqueous system (pH 3) containingNaCl as a supporting salt. Dynamic light scattering, static light scattering, electrophoretic light scattering,and dialyzing techniques were used as the experimental tool in a suitable combination. The measurementswere performed mainly at 25 C and at 0.01 M NaCl as a function of mixing ratio (rm, molar ratio ofPNIPA to HSA). The results of DLS and ELS evidently demonstrated the formation of a water-solublecomplex through mixing of HSA and PNIPA. A detailed analysis of SLS data with the aid of dialysis datarevealed that the resulting complex is an "intramolecular" complex consisting of a PNIPA chain with severalof bound HSA molecules. Both hydrodynamic radius (Rh) and radius gyration (Rg) of intramolecular complexesdecreased as rm was increased. This result correlated well to the fact that the number (n) of bound proteinsper polymer decreases with increasing rm. The size and the molar mass of the complex became large dependingon PNIPA, but the increase of PNIPA led to a decrease in n at rm < 1. The increase in NaCl concentrationfrom 0.01 to 0.3 M brought about the increase in the size and the molar mass of an intramolecular HSA-PNIPA complex prepared at rm = 1.1. This was found to be due to an increase of n. A similar trend wasobserved when temperature rose from 25 to 32 C (close to lower critical solution temperature of PNIPA).However, the effect of temperature on the increase of was strong in comparison with that of ionic strength.On the basis of these results obtained, the complexation mechanism was discussed in detail.