Chemistry Department, University of Guanajuato, L. de Retana 5, 36000, Guanajuato, Mexico.
Biological and Chemical Research Centre, Faculty of Chemistry, University of Warsaw, Żwirki i Wigury 101, 02-093, Warsaw, Poland.
J Biol Inorg Chem. 2023 Oct;28(7):655-667. doi: 10.1007/s00775-023-02016-y. Epub 2023 Aug 30.
Isotope fractionation of metals/metalloids in biological systems is an emerging research area that demands the application of state-of-the-art analytical chemistry tools and provides data of relevance to life sciences. In this work, Se uptake and Se isotope fractionation were measured during the biofortification of baker's yeast (Saccharomyces cerevisiae)-a product widely used in dietary Se supplementation and in cancer prevention. On the other hand, metabolic labeling with N is a valuable tool in mass spectrometry-based comparative proteomics. For Se-yeast, such labeling would facilitate the assessment of Se impact on yeast proteome; however, the question arises whether the presence of N in the microorganisms affects Se uptake and its isotope fractionation. To address the above-mentioned aspects, extracellularly reduced and cell-incorporated Se fractions were analyzed by hydride generation-multi-collector inductively coupled plasma-mass spectrometry (HG MC ICP-MS). It was found that extracellularly reduced Se was enriched in light isotopes; for cell-incorporated Se, the change was even more pronounced, which provides new evidence of mass fractionation during biological selenite reduction. In the presence of N, a weaker preference for light isotopes was observed in both, extracellular and cell-incorporated Se. Furthermore, a significant increase in Se uptake for N compared to N biomass was found, with good agreement between hydride generation microwave plasma-atomic emission spectrometry (HG MP-AES) and quadrupole ICP-MS results. Biological effects observed for heavy nitrogen suggest N-driven alteration at the proteome level, which facilitated Se access to cells with decreased preference for light isotopes.
生物体系中金属/类金属的同位素分馏是一个新兴的研究领域，需要应用最先进的分析化学工具，并提供与生命科学相关的数据。在这项工作中，我们测量了面包酵母（酿酒酵母）生物强化过程中硒的吸收和硒同位素分馏，该酵母是一种广泛用于膳食硒补充和癌症预防的产品。另一方面，用 N 进行代谢标记是基于质谱的比较蛋白质组学的一种有价值的工具。对于 Se-yeast，这种标记将有助于评估 Se 对酵母蛋白质组的影响；然而，问题是微生物中 N 的存在是否会影响 Se 的吸收及其同位素分馏。为了解决上述问题，我们通过氢化物发生-多接收电感耦合等离子体质谱法（HG-MC-ICP-MS）分析了细胞外还原和细胞内结合的 Se 分数。结果发现，细胞外还原的 Se 富含轻同位素；对于细胞内结合的 Se，这种变化更为明显，这为生物亚硒酸盐还原过程中的质量分馏提供了新的证据。在 N 的存在下，无论是细胞外还是细胞内结合的 Se，对轻同位素的偏好程度都较弱。此外，与 N 生物质相比，我们发现 N 对 Se 的吸收显著增加，并且氢化物发生微波等离子体原子发射光谱法（HG-MP-AES）和四极杆 ICP-MS 的结果之间具有良好的一致性。重氮的生物效应表明氮在蛋白质组水平上的驱动改变，这使得 Se 更容易进入细胞，而对轻同位素的偏好程度降低。
