...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >ELECTRON TRANSFER ACROSS THE O-2(-) GENERATING FLAVOCYTOCHROME B OF NEUTROPHILS - EVIDENCE FOR A TRANSITION FROM A LOW-SPIN STATE TO A HIGH-SPIN STATE OF THE HEME IRON COMPONENT
【24h】

ELECTRON TRANSFER ACROSS THE O-2(-) GENERATING FLAVOCYTOCHROME B OF NEUTROPHILS - EVIDENCE FOR A TRANSITION FROM A LOW-SPIN STATE TO A HIGH-SPIN STATE OF THE HEME IRON COMPONENT

机译：横跨中性子的O-2（-）生成的黄素荧光素B的电子转移-证明血红素铁组分从低旋转态转变为高旋转态的证据

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The NADPH oxidase complex of activated neutrophils consists of a membrane-bound flavocytochrome b and cytosolic activation factors. Despite its ability to react with Oz, the heme b component of the flavocytochrome is insensitive to cyanide and CO, and slowly reactive to butyl isocyanide, We report here that arachidonic acid, an anionic amphophil which elicits oxidase activation in a cell-free system induces a transition of the heme iron of the neutrophil flavocytochrome b from a low-spin hexacoordinated state to a high-spin pentacoordinated state and promotes the binding of butyl isocyanide to the heme b. Low-temperature EPR spectra of air-oxidized flavocytochrome b either purified or in its membrane-bound form showed a low-spin signal at g = 3.26 and a high-spin signal at g = 6.0. Upon addition of arachidonic acid, the g = 3.26 signal vanished; a low-spin signal at a = 2.23 appeared, and the signal at g = 6.0 progressively increased, The subsequent addition of butyl isocyanide resulted in the decrease of the g = 6.0 and g = 2.23 signals and in the appearance of a new low-spin signal at g = 2.33. Consistent with the EPR results, upon addition of arachidonic acid to oxidized flavocytochrome b, a 2.5 nm blue shift of the Sent peak was detected in low-temperature optical spectra, The subsequent addition of butyl isocyanide resulted in the emergence of a peak at 432 nm reflecting the formation of a butyl isocyanide-oxidized heme b complex. In the case of sodium dithionite-reduced flavocytochrome b, arachidonic acid promoted the binding of butyl isocyanide to the reduced heme b, as shown by the emergence of a peak at 434 nm and the decrease of the a band at 558 nm, The same promoting effect was encountered with sodium dodecyl sulfate, an anionic amphophil capable of eliciting oxidase activation like arachidonic acid. In contrast to arachidonic acid, arachidonic acid methyl ester was ineffective and counteracted the effect of arachidonic acid. Butyl isocyanide added to intact neutrophils was found to bind to heme b, only after the cells have been activated. These data demonstrate the transient accumulation of a pentacoordinated form of the heme iron of flavocytochrome b under in vitro and in vivo conditions; the pentacoordinated form of the reduced heme b is postulated to react with O-2 to generate the superoxide anion.
机译：活化的中性粒细胞的NADPH氧化酶复合物由膜结合的黄素细胞色素b和胞质活化因子组成。尽管其能够与Oz反应，但黄素细胞色素的血红素b成分对氰化物和CO不敏感，并且对丁基异氰酸酯具有缓慢反应性。我们在此报告，花生四烯酸是一种阴离子两性亲子，可在无细胞系统中引发氧化酶活化，中性粒细胞黄细胞色素b的血红素铁从低旋六配位态转变为高旋五配位态，并促进异氰酸丁酯与血红素b的结合。纯化的或膜结合形式的空气氧化的黄细胞色素b的低温EPR谱在g = 3.26时显示低旋转信号，在g = 6.0时显示高旋转信号。加入花生四烯酸后，g ＝ 3.26的信号消失;在a = 2.23处出现低旋转信号，并且在g = 6.0处的信号逐渐增加。随后添加异氰酸丁酯导致g = 6.0和g = 2.23信号减少，并出现了新的低信号。 g = 2.33时的自旋信号。与EPR结果一致，将花生四烯酸添加到氧化的黄细胞色素b中后，在低温光谱中检测到Sent峰出现了2.5 nm的蓝移;随后添加的异氰酸丁酯导致在432 nm处出现一个峰反映了异氰酸丁酯氧化的血红素b络合物的形成。在连二亚硫酸钠还原的黄细胞色素b的情况下，花生四烯酸促进了异氰酸丁酯与还原血红素b的结合，如在434 nm处出现一个峰和在558 nm处出现a谱带的减少所表明，同样的促进作用十二烷基硫酸钠是一种能引起氧化酶活化的阴离子两性亲和剂，如花生四烯酸，也能达到这种效果。与花生四烯酸相反，花生四烯酸甲酯无效并抵消了花生四烯酸的作用。发现仅在激活细胞后，添加到完整嗜中性粒细胞中的异氰酸丁酯才能与血红素b结合。这些数据证明了在体外和体内条件下，五配体形式的黄素细胞色素b血红素铁的瞬时积累;假定还原血红素b的五配位形式与O-2反应生成超氧阴离子。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号