Visualizing the interaction between poly-L-lysine and poly( acrylic acid) microgels using microscopy techniques: Effect of electrostatics and peptide size
Visualizing the interaction between poly-L-lysine and poly( acrylic acid) microgels using microscopy techniques: Effect of electrostatics and peptide size
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DOI：
10.1021/la060452a
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发表时间：
2006-06-06
期刊：
影响因子：
3.9
通讯作者：
Malmsten, Martin
中科院分区：
文献类型：
--
作者：
Bysell, Helena;Malmsten, Martin
研究了轻度交联的聚丙烯酸（pAA）微凝胶（直径50-150 μ m）与聚赖氨酸（pLys）之间的相互作用随pH、离子强度、肽大小和浓度的变化。微凝胶颗粒内的多肽的溶胀响应和分布通过显微操作器辅助的光学显微镜和共聚焦激光扫描显微镜监测，而pLys在微凝胶中的结合等温线通过荧光光度法测定。用圆二色谱法研究了pLys的构象变化。发现pLys的分子量影响肽诱导的微凝胶去溶胀的程度，这主要是由于肽的限制大于有效网络筛目尺寸以穿透整个凝胶。大肽集中在凝胶颗粒的表面层内，并且在低离子强度下，该致密表面层显示出作为化合物进一步渗透到凝胶核心中的主要空间屏障。然而，小肽均匀地分布在整个微凝胶颗粒中，并且能够产生大的微凝胶体积减少。微凝胶的去溶胀随着pH的降低而增加，而pLys的摄取在低pH下显著降低。离子强度对pLys和带相反电荷的pAA微凝胶的相互作用的影响是中等的，并且仅在高pH下对凝胶的去溶胀显著。对于高分子量肽，观察到与带相反电荷的微凝胶相互作用的pLys的α-螺旋含量的显著增加，并且正如所预期的，α-螺旋形成的程度在高pH下更明显，即，微凝胶的电荷密度高，但肽的电荷密度降低。
The interaction between lightly cross-linked poly(acrylic acid) (pAA) microgels (50-150 Am in diameter) and poly-L-lysine (pLys) was studied as a function of pH, ionic strength, peptide size, and concentration. The swelling response and distribution of polypeptides within microgel particles was monitored by micromanipulator-assisted light microscopy and confocal laser scanning microscopy, while binding isotherms of pLys in the microgels were determined spectrophotometrically. Conformational changes of pLys were investigated by circular dichroism. The molecular weight of pLys was found to influence the degree of peptide-induced microgel deswelling, largely due to limitation of peptides larger than the effective network mesh size to penetrate the entire gel. Large peptides were concentrated within a surface layer of the gel particles, and at low ionic strength this dense surface layer was shown to act as a largely steric barrier for further penetration of compounds into the gel core. Small peptides, however, distributed evenly throughout the microgel particles and were able to create large microgel volume reductions. The deswelling of microgels increased with decreasing pH, while the uptake of pLys was significantly reduced at low pH. The effect of ionic strength on the interactions of pLys and oppositely charged pAA microgels was moderate and only pronounced for deswelling of gels at high pH. A significant increase in the alpha-helix content of pLys interacting with the oppositely charged microgels was observed for high molecular weight peptides, and the extent of alpha-helix formation was as expected more pronounced at high pH, i.e., at high charge density of the microgels but reduced charge density of the peptides.