King's Lab, School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China.
Br J Pharmacol. 2011 May;163(2):399-412. doi: 10.1111/j.1476-5381.2011.01227.x.
Exenatide is a 39-amino-acid peptide widely used to manage type 2 diabetes mellitus. However, it has a short plasma half-life and requires a twice daily injection regime. To overcome these drawbacks we used maleimide-polyethylene glycol to induce site-specific PEGylation.
The analogue PB-105 (ExC39) was produced by replacing cysteine at position 39 of exenatide to provide a free thiol group. PB-105 showed the same glucoregulatory activity as exenatide in mice. Site-specific PEGylation of PB-105 was performed to produce PB-110 (ExC39PEG5kDa), PB-106 (ExC39PEG20kDa), PB-107 (ExC39PEG30kDa) and PB-108 (ExC39PEG40kDa). Their effects on intracellular cAMP, acute glucoregulatory activity and pharmacokinetic profile were compared in mice and rats.
PEGylation shifted the concentration-response curve of PB-105 to the right in a parallel, polyethylene glycol mass-dependent manner but with an inflexion point of at least 20 kDa. The activities of PB-107 and PB-108 but not PB-106 were reduced by 90% and 99%. PEGylation affected in vivo glucoregulatory activity in the same 'Inflexion-Shift' fashion at least at 20 kDa, but linearly increased plasma duration and systemic exposure without inflexion. PB-106 had a plasma t(1/2) approximately 10-fold that of PB-105, and exhibited superior glucoregulatory activity compared with PB-105 in normal and diabetic mice.
Site-specific PEGylation of exenatide with a permanent amide linkage affects its activity in a new type of 'Inflexion-Shift' fashion. PB-106 is a putative new analogue for treating diabetes; it possesses no loss of in vitro activity, prolonged plasma duration and superior, improved in vivo glucoregulatory activity compared with exenatide.
艾塞那肽是一种由 39 个氨基酸组成的肽，广泛用于治疗 2 型糖尿病。然而，它的血浆半衰期较短，需要每天注射两次。为了克服这些缺点，我们使用马来酰亚胺-聚乙二醇诱导定点 PEG 化。
通过将位置 39 的半胱氨酸替换为艾塞那肽，产生类似物 PB-105（ExC39），从而提供一个游离的巯基。PB-105 在小鼠中表现出与艾塞那肽相同的血糖调节活性。对 PB-105 进行定点 PEG 化，得到 PB-110（ExC39PEG5kDa）、PB-106（ExC39PEG20kDa）、PB-107（ExC39PEG30kDa）和 PB-108（ExC39PEG40kDa）。在小鼠和大鼠中比较了它们对细胞内 cAMP、急性血糖调节活性和药代动力学特征的影响。
PEG 化以平行、聚乙二醇质量依赖性的方式将 PB-105 的浓度-反应曲线向右移动，但拐点至少为 20 kDa。PB-107 和 PB-108 的活性降低了 90%和 99%，但 PB-106 的活性没有降低。PEG 化以至少 20 kDa 的相同“拐点-移位”方式影响体内血糖调节活性，但呈线性增加血浆持续时间和全身暴露，没有拐点。PB-106 的血浆 t(1/2)约为 PB-105 的 10 倍，在正常和糖尿病小鼠中表现出优于 PB-105 的血糖调节活性。
艾塞那肽的定点 PEG 化与永久酰胺键结合，以一种新的“拐点-移位”方式影响其活性。PB-106 是一种潜在的新型糖尿病治疗药物，与艾塞那肽相比，它不丧失体外活性，延长了血浆持续时间，并具有更好、更优的体内血糖调节活性。
