Hemoglobin-like proteins found in the single-celled organisms.

(1)利用Sephadex G-50凝胶过滤和cm -纤维素层析，成功地从一种纤毛原生动物（梨形四膜虫）中分离出一种血红蛋白样蛋白。其铁离子形式的Soret吸收光谱和磁圆二色性光谱与哺乳动物肌红蛋白非常相似，表明其轴向水分子可能是由远端组氨酸残基稳定的。(2)直接从酵母菌（norvegensis）中分离到一种血红蛋白样蛋白，在10 mM磷酸缓冲液pH7.0中测定其CD谱。所得的平均残余摩尔椭圆度在222 nm处为13700°cm^2 dmol^<-1>，与作为参考的抹香鲸肌红蛋白的[rheta]^<MRW>_=-25400°cm^2 dmol^<-1>相比，这个值是非常不寻常的。在几条证据的基础上，我们提出了酵母血红蛋白的独特结构。

(1) We have succeeded in isolating a hemoglobin-like protein from a ciliated protozoa (Tetrahymena pyriformis) by using gel filtration on Sephadex G-50 followed by CM-celluloce chromatography. The Soret absorption and magnetic-circular-dichroic spectra for its ferric met form were very similar to those of mammalian myoglobins, indicating that its axial water molecule is stabilized probably by a distal histidine residue.(2) A hemoglobin-like protein was directly isolated from yeast (Candida norvegensis) and its CD spectrum was measured in 10 mM phosphate buffer, pH7.0. The resultant mean residue molar ellipticity at 222 nm was found to be-13700 deg cm^2 dmol^<-1>, this value being extremely unusual as compared with [rheta]^<MRW>_=-25400 deg cm^2 dmol^<-1> for sperm whale myoglobin used as a reference. On the basis of several lines of evidence, we propose an unique structure of yeast hemoglobin.