Factor IX oligomerization underlies reduced activity upon disruption of physiological conditions
Factor IX oligomerization underlies reduced activity upon disruption of physiological conditions
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DOI：
10.1111/hae.12356
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发表时间：
2014-03-01
期刊：
影响因子：
3.9
通讯作者：
Kimchi-Sarfaty, C.
中科院分区：
文献类型：
--
作者：
Simhadri, V. L.;Hamasaki-Katagiri, N.;Kimchi-Sarfaty, C.
凝血因子IX （Coagulation factor IX， FIX）是一种丝氨酸蛋白酶，在血液凝血级联中起关键作用。FIX缺乏会导致血友病b。FIX是由461个氨基酸合成的前肽，经过加工后分泌到血浆中。该蛋白经过多种修饰，包括但不限于糖基化、γ -羧基化和二硫键形成。经过加工和有限的蛋白质水解，蛋白质转化为活性蛋白酶。在生理条件下，FIX酶原为单体。本工作的目的是分析可能影响FIX单体状态和促进和/或减少寡聚化的条件。利用天然凝胶电泳和尺寸排除色谱，我们发现在降低pH和离子强度的条件下，FIX酶原可以低聚，从而形成更高分子量的物种，同时比活性降低。同样，FIX低聚物在低牛血清白蛋白（BSA）浓度下容易形成；然而，BSA浓度的增加阻碍了FIX的寡聚化。我们假设正常的血液生理条件对于维持活性FIX单体至关重要。在与酸中毒、电解质失衡和低白蛋白水平相关的应激条件下，FIX寡聚化预计会发生，从而导致活性受损。此外，白蛋白作为一种常用的药物稳定剂，可能通过减少寡聚而增强FIX生物药物的疗效。
Coagulation factor IX (FIX) is a serine protease that plays a pivotal role in the blood coagulation cascade. FIX deficiency leads to a blood clotting disorder known as haemophilia B. FIX, synthesized as a prepro‐peptide of 461 amino acids, is processed and secreted into plasma. The protein undergoes numerous modifications, including, but not limited to glycosylation, γ‐carboxylation and disulphide bond formation. Upon processing and limited proteolysis, the protein is converted into an active protease. Under physiological conditions, the FIX zymogen is a monomer. The purpose of this work was to analyse the conditions that may affect FIX monomeric state and promote and/or reduce oligomerization. Using native gel electrophoresis and size exclusion chromatography, we found that under decreased pH and ionic strength conditions, the FIX zymogen can oligomerize, resulting in the formation of higher molecular weight species, with a concomitant reduction in specific activity. Similarly, FIX oligomers formed readily with low bovine serum albumin (BSA) concentrations; however, increased BSA concentrations impeded FIX oligomerization. We hypothesize that normal blood physiological conditions are critical for maintaining active FIX monomers. Under conditions of stress associated with acidosis, electrolyte imbalance and low albumin levels, FIX oligomerization is expected to take place thus leading to compromised activity. Furthermore, albumin, which is commonly used as a drug stabilizer, may enhance the efficacy of FIX biological drugs by reducing oligomerization.