Kho R, Nguyen L, Torres-Martínez C L, Mehra R K
Department of Neuroscience, University of California, Riverside 92521, USA.
Biochem Biophys Res Commun. 2000 May 27;272(1):29-35. doi: 10.1006/bbrc.2000.2712.
Histidine is a chelator of zinc, most notably in zinc-finger proteins (zinc coordinated by cysteine and histidine) and in hyperaccumulator plants. Sulfide incorporation into molecules containing metal-cysteinyl complexes has been shown to occur in vivo in certain yeasts, leading to enhanced metal tolerance. Demonstrated here for the first time is incorporation of sulfide into zinc-histidine, resulting in histidine-ZnS nanocrystals (NCs) having unique optical properties. Sulfide complexation occurred optimally at alkaline pH into zinc-(histidine)2 species, and UV/Vis absorption maxima were red-shifted as increasing sulfide addition occurred. Intermediate sulfide concentrations led to multiple, thermodynamically preferred NC species within a sample. Fluorescence of histidine-ZnS NCs was greater than ZnS prepared previously with cysteinyl peptides. Transmission electron microscopy and selected-area electron diffraction indicated hexagonal ZnS crystals having an average size of 4.2 nm. A photocatalytic application of histidine-ZnS NCs was shown by efficient degradation of p-nitrophenol and paraquat in the presence of UV irradiation.
组氨酸是锌的螯合剂，在锌指蛋白（锌由半胱氨酸和组氨酸配位）和超积累植物中尤为明显。已证明在某些酵母体内，硫化物会掺入含有金属 - 半胱氨酰配合物的分子中，从而提高金属耐受性。首次在此证明硫化物掺入锌 - 组氨酸中，形成具有独特光学性质的组氨酸 - 硫化锌纳米晶体（NCs）。硫化物络合在碱性pH下对锌 -（组氨酸）₂物种最为有利，随着硫化物添加量增加，紫外/可见吸收最大值发生红移。中等硫化物浓度导致样品中出现多种热力学上更稳定的NC物种。组氨酸 - 硫化锌NCs的荧光大于先前用半胱氨酰肽制备的硫化锌。透射电子显微镜和选区电子衍射表明形成了平均尺寸为4.2 nm的六方硫化锌晶体。在紫外线照射下，组氨酸 - 硫化锌NCs对硝基苯酚和百草枯的有效降解表明了其光催化应用。
