通过脉冲电子顺磁共振光谱法证明蝶豆亚科凝集素中锰离子（Mn2+）位点存在一个保守的组氨酸和两个水配体。

Demonstration of a conserved histidine and two water ligands at the Mn2+ site in Diocleinae lectins by pulsed EPR spectroscopy.

作者信息

Lee H C, Goroncy A K, Peisach J, Cavada B S, Grangeiro T B, Ramos M V, Sampaio A H, Dam T K, Brewer C F

机构信息

Departments of Molecular Pharmacology, Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.

出版信息

Biochemistry. 2000 Mar 7;39(9):2340-6. doi: 10.1021/bi992102b.

DOI:10.1021/bi992102b

PMID:10694401

Abstract

Lectins from the Diocleinae subtribe, including Canavalia brasiliensis, Canavalia bonariensis, Canavalia grandiflora, Cratylia floribunda, Dioclea grandiflora, Dioclea guianensis, Dioclea rostrata, Dioclea violacea, and Dioclea virgata, have been recently isolated and characterized in terms of their carbohydrate binding specificities. Although all of the lectins are Man/Glc specific, they possess different biological activities. In the present study, electron paramagnetic resonance (EPR) spectroscopy demonstrates that all nine Diocleinae lectins contain Mn2+. The spectra of C. floribunda and D. rostrata suggest Mn2+ site symmetry different from that of the other seven lectins. However, electron spin-echo envelope modulation (ESEEM) spectroscopy indicates that all nine lectins are coordinated to a histidyl imidazole, with similar electron-nuclear coupling to the Mn2+-bound imidazole nitrogen. ESEEM also demonstrates ligation of two water molecules to Mn2+ in all nine Diocleinae lectins. Thus, the EPR and ESEEM data indicate the presence of a Mn2+ binding site in the above Diocleinae lectins with a conserved histidine residue and two water ligands.

摘要

来自豆薯亚族的凝集素，包括巴西刀豆、布宜诺斯艾利斯刀豆、大花刀豆、多花克拉蒂亚豆、大花薯豆、圭亚那薯豆、具喙薯豆、紫花薯豆和长茎薯豆，最近已被分离出来，并根据它们的碳水化合物结合特异性进行了表征。尽管所有这些凝集素都对甘露糖/葡萄糖具有特异性，但它们具有不同的生物学活性。在本研究中，电子顺磁共振（EPR）光谱表明，所有九种豆薯亚族凝集素都含有锰离子（Mn2+）。多花克拉蒂亚豆和具喙薯豆的光谱表明，锰离子位点的对称性与其他七种凝集素不同。然而，电子自旋回波包络调制（ESEEM）光谱表明，所有九种凝集素都与一个组氨酸咪唑配位，与锰离子结合的咪唑氮具有相似的电子-核耦合。ESEEM还表明，在所有九种豆薯亚族凝集素中，有两个水分子与锰离子配位。因此，EPR和ESEEM数据表明，上述豆薯亚族凝集素中存在一个锰离子结合位点，该位点有一个保守的组氨酸残基和两个水配体。