Five-coordinate H64Q neuroglobin as a ligand-trap antidote for carbon monoxide poisoning
Five-coordinate H64Q neuroglobin as a ligand-trap antidote for carbon monoxide poisoning
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DOI：
10.1126/scitranslmed.aah6571
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发表时间：
2016-12-07
影响因子：
17.1
通讯作者：
Gladwin, Mark T.
中科院分区：
文献类型：
--
作者：
Azarov, Ivan;Wang, Ling;Gladwin, Mark T.
一氧化碳（CO）是全世界中毒死亡的主要原因，没有可用的解毒疗法。我们介绍了一个潜在的治疗模式，一氧化碳中毒的基础上，近不可逆的结合CO的工程人类脑红蛋白（Ngb）。Ngb是一种六配位血红素蛋白，其中血红素铁由两个组氨酸残基配位。我们将远端组氨酸突变为谷氨酰胺（H64 Q），并将三个表面半胱氨酸用反应性较低的氨基酸取代，形成五配位血红素蛋白（Ngb-H64 Q-CCC）。该分子对气态配体表现出异常高的亲和力，对氧的P-50（血红蛋白半饱和时的O-2分压）值为0.015 mmHg。Ngb-H64 Q-CCC与CO的结合比血红蛋白强约500倍。将Ngb-H64 Q-CCC与100%CO饱和血红蛋白（无细胞或包封在人红细胞中）一起孵育，将碳氧血红蛋白的半衰期分别从血红蛋白或红细胞仅暴露于空气时的>= 200分钟减少到0.11和0.41分钟。向CO中毒小鼠输注Ngb-H64 Q-CCC可增强红细胞中CO的清除，恢复心率和血压，增加存活率，随后CO结合的Ngb-H64 Q-CCC在肾脏中快速消除。具有非常高的CO结合亲和力的基于血红素的清除剂分子，例如我们的突变的五配位Ngb，由于其结合和消除CO的能力，是CO中毒的潜在解毒剂。
Carbon monoxide (CO) is a leading cause of poisoning deaths worldwide, with no available antidotal therapy. We introduce a potential treatment paradigm for CO poisoning, based on near-irreversible binding of CO by an engineered human neuroglobin (Ngb). Ngb is a six-coordinate hemoprotein, with the heme iron coordinated by two histidine residues. We mutated the distal histidine to glutamine (H64Q) and substituted three surface cysteines with less reactive amino acids to form a five-coordinate heme protein (Ngb-H64Q-CCC). This molecule exhibited an unusually high affinity for gaseous ligands, with a P-50 (partial pressure of O-2 at which hemoglobin is half-saturated) value for oxygen of 0.015 mmHg. Ngb-H64Q-CCC bound CO about 500 times more strongly than did hemoglobin. Incubation of Ngb-H64Q-CCC with 100% CO-saturated hemoglobin, either cell-free or encapsulated in human red blood cells, reduced the half-life of carboxyhemoglobin to 0.11 and 0.41 min, respectively, from >= 200 min when the hemoglobin or red blood cells were exposed only to air. Infusion of Ngb-H64Q-CCC to CO-poisoned mice enhanced CO removal from red blood cells, restored heart rate and blood pressure, increased survival, and was followed by rapid renal elimination of CO-bound Ngb-H64Q-CCC. Heme-based scavenger molecules with very high CO binding affinity, such as our mutant five-coordinate Ngb, are potential antidotes for CO poisoning by virtue of their ability to bind and eliminate CO.