NITRIC-OXIDE CIRCULATES IN MAMMALIAN PLASMA PRIMARILY AS AN S-NITROSO ADDUCT OF SERUM-ALBUMIN
NITRIC-OXIDE CIRCULATES IN MAMMALIAN PLASMA PRIMARILY AS AN S-NITROSO ADDUCT OF SERUM-ALBUMIN
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DOI：
10.1073/pnas.89.16.7674
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发表时间：
1992-08-15
影响因子：
11.1
通讯作者：
LOSCALZO, J
中科院分区：
文献类型：
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作者：
STAMLER, JS;JARAKI, O;LOSCALZO, J
我们最近发现，在生物系统中产生的一氧化氮或真正的内皮衍生松弛因子在特定的蛋白质硫醇存在下发生反应，形成具有内皮松弛因子样特性的S亚硝基蛋白衍生物。血清白蛋白的单一游离半胱氨酸，Cys-34，在生理条件下对氮氧化物(最有可能是亚硝酸根离子)特别敏感，主要是因为它的pk异常低；考虑到它在血浆中的丰富，其中它占几乎等于-到0.5 mM的硫醇，我们假设这种血浆蛋白作为内皮细胞产生的一氧化氮的储存库。为了验证这一假设，我们建立了一种化学发光检测方法，即在与臭氧反应之前，利用紫外光降解S-NO键，从而测定生物体系中的游离一氧化氮、S-亚硝硫醇和S-亚硝基蛋白质。我们发现，人血浆中含有几乎相当于7 mU-M的S亚硫醇，其中96%是S亚硝基蛋白，其中82%是S亚硝基血清白蛋白。相比之下，血浆游离一氧化氮水平仅在3-NM范围内。在兔血浆中，S-亚硫醇的含量几乎等于1-mU-M，给药60分钟后，选择性和强效的一氧化氮合酶抑制剂N(G)-单甲基L-精氨酸使S-亚硫醇降低了近40%(其中95%是S亚硝基蛋白，几乎等于80%是S亚硝基血清白蛋白)，并伴有平均动脉压升高22%。这些数据表明，血浆中天然产生的一氧化氮主要以S亚硝硫醇类络合物为主，其中主要是S亚硝基-血清白蛋白。这种丰富的、相对长寿的加合物可能是一个储存库，通过它可以调节血浆中高活性、短暂的游离一氧化氮水平，以维持血管紧张性。
We have recently shown that nitric oxide or authentic endothelium-derived relaxing factor generated in a biologic system reacts in the presence of specific protein thiols to form S-nitrosoprotein derivatives that have endothelium-derived relaxing factor-like properties. The single free cysteine of serum albumin, Cys-34, is particularly reactive toward nitrogen oxides (most likely nitrosonium ion) under physiologic conditions, primarily because of its anomalously low pK; given its abundance in plasma, where it accounts for almost-equal-to 0.5 mM thiol, we hypothesized that this plasma protein serves as a reservoir for nitric oxide produced by the endothelial cell. To test this hypothesis, we developed a methodology, which involves UV photolytic cleavage of the S-NO bond before reaction with ozone for chemiluminescence detection, with which to measure free nitric oxide, S-nitrosothiols, and S-nitrosoproteins in biologic systems. We found that human plasma contains almost-equal-to 7-mu-M S-nitrosothiols, of which 96% are S-nitrosoproteins, 82% of which is accounted for by S-nitroso-serum albumin. By contrast, plasma levels of free nitric oxide are only in the 3-nM range. In rabbits, plasma S-nitrosothiols are present at almost-equal-to 1-mu-M; 60 min after administration of N(G)-monomethyl-L-arginine at 50 mg/ml, a selective and potent inhibitor of nitric oxide synthetases, S-nitrosothiols decreased by almost-equal-to 40% (>95% of which were accounted for by S-nitrosoproteins, and almost-equal-to 80% of which was S-nitroso-serum albumin); this decrease was accompanied by a concomitant increase in mean arterial blood pressure of 22%. These data suggest that naturally produced nitric oxide circulates in plasma primarily complexed in S-nitrosothiol species, principal among which is S-nitroso-serum albumin. This abundant, relatively long-lived adduct likely serves as a reservoir with which plasma levels of highly reactive, short-lived free nitric oxide can be regulated for the maintenance of vascular tone.