Department of Pharmacy, Uppsala University, P.O. Box 580, SE-751 23 Uppsala, Sweden.
Biomacromolecules. 2013 Jul 8;14(7):2317-25. doi: 10.1021/bm400431f. Epub 2013 Jun 17.
Proteolytic degradation and release of microgel-bound peptides was investigated for trypsin, poly(acrylic acid-co-acrylamide) microgels (70-90 μm in diameter), and oppositely charged polylysine, using a method combination of confocal microscopy and micromanipulator-assisted light microscopy. Results show that trypsin-induced release of polylysine increased with increasing trypsin concentration, decreasing microgel charge density and decreasing peptide molecular weight. While the microgel offered good protection against enzymatic degradation at high microgel charge density, it was also observed that the cationic peptide enabled trypsin to bind throughout the peptide-loaded microgels, even when it did not bind to the peptide-void ones. With the exception of highly charged microgels, proteolytic degradation throughout the peptide-loaded microgel resulted in the generation of short and non-adsorbing peptide stretches, giving rise to the concentration and peptide length dependence observed. A simple random scission model was able to qualitatively capture these experimental findings. Collectively, the results demonstrate that microgel charge density, peptide molecular weight, and enzyme concentration greatly influence degradation/release of microgel-bound peptides and need to be considered in the use of microgels, e.g., as carriers for protein and peptide drugs.
研究了蛋白酶、聚（丙烯酸-co-丙烯酰胺）微凝胶（直径 70-90μm）和带相反电荷的聚赖氨酸对微凝胶结合肽的蛋白水解降解和释放，采用共聚焦显微镜和微操纵器辅助的激光显微镜的方法组合。结果表明，随着胰蛋白酶浓度的增加、微凝胶电荷量密度的降低和肽分子量的降低，胰蛋白酶诱导的聚赖氨酸释放增加。虽然微凝胶在高微凝胶电荷量密度下对酶降解提供了良好的保护，但也观察到阳离子肽使胰蛋白酶能够结合整个载肽微凝胶，即使它不与载肽空微凝胶结合。除了高电荷量的微凝胶外，整个载肽微凝胶中的蛋白水解降解导致产生短的和非吸附的肽段，从而导致观察到的浓度和肽长度依赖性。简单的随机断裂模型能够定性地捕捉到这些实验结果。总的来说，这些结果表明，微凝胶电荷量、肽分子量和酶浓度极大地影响了微凝胶结合肽的降解/释放，在使用微凝胶作为蛋白质和肽类药物的载体时需要加以考虑。
