Suppr超能文献

可以从蜡样芽孢杆菌中纯化出两种不同的aa3型细胞色素。

Two different aa3-type cytochromes can be purified from the bacterium Bacillus cereus.

作者信息

Garcia-Horsman J A, Barquera B, Escamilla J E

机构信息

Departamento de Microbiología, Universidad Nacional Autónoma de México.

出版信息

Eur J Biochem. 1991 Aug 1;199(3):761-8. doi: 10.1111/j.1432-1033.1991.tb16181.x.

Abstract

Two aa3-type cytochromes were purified from membranes of sporulating Bacillus cereus. One of them, an aa3 complex, was found to be composed of two subunits (51 and 31 kDa), two a hemes and three copper atoms, thus being similar to the cytochrome aa3 previously purified from vegetative B. cereus [García-Horsman, J. A., Barquera, B., González-Halphen, D. & Escamilla, J. E. (1991) Mol. Microbiol. 5, 197-205]. The second isoform, a caa3 complex, was expressed in sporulating cells only, and was found to be composed of two subunits (51 and 37 kDa). The 37-kDa subunit (subunit II) is a heme-c-containing polypeptide as shown by its peroxidase activity in SDS/PAGE gels and by its spectral features. Both subunits of the caa3 complex immunologically cross-reacted with antiserum raised against B. cereus cytochrome aa3, suggesting homology between the two enzymes. Also, the heme-c-containing subunit of the caa3 complex was reactive with anti-(bovine cytochrome c) antiserum, but not with anti-(bovine cytochrome c1) antiserum. In addition to one heme c and two hemes a, the caa3 complex contained three copper atoms. Kinetic comparison of aa3 and caa3 complexes revealed that the latter is slightly more active (k = 150 s-1) and has a lower affinity to yeast cytochrome c (Km = 76 microM) and to oxygen (Km = 2 microM) as compared with cytochrome aa3 (100 s-1, 10 microM, and 5 microM, respectively).

摘要

从蜡样芽孢杆菌芽孢形成期的细胞膜中纯化出了两种aa3型细胞色素。其中一种是aa3复合物,由两个亚基(51 kDa和31 kDa)、两个a型血红素和三个铜原子组成,因此与先前从营养期蜡样芽孢杆菌中纯化出的细胞色素aa3相似[加西亚 - 霍斯曼,J. A.,巴尔克拉,B.,冈萨雷斯 - 哈尔芬,D. & 埃斯卡米拉,J. E.(1991年)《分子微生物学》5卷,第197 - 205页]。第二种同工型是caa3复合物,仅在芽孢形成期细胞中表达,由两个亚基(51 kDa和37 kDa)组成。37 kDa的亚基(亚基II)是一种含血红素c的多肽,这在SDS / PAGE凝胶中的过氧化物酶活性及其光谱特征中得到了体现。caa3复合物的两个亚基与针对蜡样芽孢杆菌细胞色素aa3产生的抗血清发生免疫交叉反应,表明这两种酶之间存在同源性。此外,caa3复合物的含血红素c的亚基与抗(牛细胞色素c)抗血清有反应,但与抗(牛细胞色素c1)抗血清无反应。除了一个血红素c和两个血红素a外,caa3复合物还含有三个铜原子。对aa3和caa3复合物的动力学比较表明,与细胞色素aa3(分别为100 s-1、10 microM和5 microM)相比,后者活性略高(k = 150 s-1),对酵母细胞色素c(Km = 76 microM)和氧气(Km = 2 microM)的亲和力较低。

文献AI研究员

20分钟写一篇综述,助力文献阅读效率提升50倍。

立即体验

用中文搜PubMed

大模型驱动的PubMed中文搜索引擎

马上搜索

文档翻译

学术文献翻译模型,支持多种主流文档格式。

立即体验