Romberg Birgit, Metselaar Josbert M, deVringer Tom, Motonaga Kei, Kettenes-van den Bosch J Jantina, Oussoren Christien, Storm Gert, Hennink Wim E
Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands.
Bioconjug Chem. 2005 Jul-Aug;16(4):767-74. doi: 10.1021/bc0497719.
Liposomes coated with poly(hydroxyethyl L-glutamine) (PHEG) show prolonged circulation times and biodistribution patterns comparable to PEG-coated liposomes. While PEG is a nondegradable polymer, PHEG is expected to be hydrolyzed by proteases. In this study the enzymatic degradability of PHEG both in its free form and grafted onto liposomes was investigated, using the proteases papain, pronase E, and cathepsin B. Enzymatic action was monitored with a ninhydrin assay, which quantifies amine groups formed due to hydrolysis of amide bonds, and the degradation products were characterized by MALDI-ToF mass spectrometry. PHEG, both in its free form and when grafted onto liposomes, showed degradation into low molecular weight peptides by the enzymes. Thus, we present a polymer-coated long-circulating liposome with an enzymatically degradable coating polymer, avoiding the risk of cellular accumulation.
涂覆有聚（L-谷氨酰胺羟乙酯）（PHEG）的脂质体显示出与聚乙二醇（PEG）涂覆的脂质体相当的延长循环时间和生物分布模式。虽然PEG是一种不可降解的聚合物，但预计PHEG会被蛋白酶水解。在本研究中，使用木瓜蛋白酶、链霉蛋白酶E和组织蛋白酶B研究了游离形式以及接枝到脂质体上的PHEG的酶促降解性。用茚三酮测定法监测酶促作用，该方法可对由于酰胺键水解形成的胺基进行定量，并用基质辅助激光解吸电离飞行时间质谱（MALDI-ToF质谱）对降解产物进行表征。游离形式以及接枝到脂质体上的PHEG均显示被这些酶降解为低分子量肽。因此，我们提出了一种具有可酶促降解的包衣聚合物的聚合物包被的长循环脂质体，避免了细胞蓄积的风险。
