Department of Chemistry, Princeton University, Princeton, NJ 08544.
Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, NJ 08544.
Proc Natl Acad Sci U S A. 2022 Dec 20;119(51):e2204050119. doi: 10.1073/pnas.2204050119. Epub 2022 Dec 12.
De novo proteins constructed from novel amino acid sequences are distinct from proteins that evolved in nature. Construct K (ConK) is a binary-patterned de novo designed protein that rescues from otherwise toxic concentrations of copper. ConK was recently found to bind the cofactor PLP (pyridoxal phosphate, the active form of vitamin B). Here, we show that ConK catalyzes the desulfurization of cysteine to HS, which can be used to synthesize CdS nanocrystals in solution. The CdS nanocrystals are approximately 3 nm, as measured by transmission electron microscope, with optical properties similar to those seen in chemically synthesized quantum dots. The CdS nanocrystals synthesized using ConK have slower growth rates and a different growth mechanism than those synthesized using natural biomineralization pathways. The slower growth rate yields CdS nanocrystals with two desirable properties not observed during biomineralization using natural proteins. First, CdS nanocrystals are predominantly of the zinc blende crystal phase; this is in stark contrast to natural biomineralization routes that produce a mixture of zinc blende and wurtzite phase CdS. Second, in contrast to the growth and eventual precipitation observed in natural biomineralization systems, the CdS nanocrystals produced by ConK stabilize at a final size. Future optimization of CdS nanocrystal growth using ConK-or other de novo proteins-may help to overcome the limits on nanocrystal quality typically observed from natural biomineralization by enabling the synthesis of more stable, high-quality quantum dots at room temperature.
从头设计的新型氨基酸序列的蛋白质与自然进化的蛋白质不同。构建 K（ConK）是一种二元模式从头设计的蛋白质，可以挽救 otherwise toxic concentrations of copper（铜）。最近发现 ConK 结合辅因子 PLP（吡哆醛磷酸，维生素 B 的活性形式）。在这里，我们表明 ConK 催化半胱氨酸的脱硫作用生成 HS，可用于在溶液中合成 CdS 纳米晶体。CdS 纳米晶体的尺寸约为 3nm，通过透射电子显微镜测量，其光学性质与化学合成量子点相似。使用 ConK 合成的 CdS 纳米晶体的生长速率较慢，并且具有与使用天然生物矿化途径合成的 CdS 纳米晶体不同的生长机制。较慢的生长速率导致 CdS 纳米晶体具有在使用天然蛋白质进行生物矿化时未观察到的两个理想特性。首先，CdS 纳米晶体主要为闪锌矿晶相；这与产生闪锌矿和纤锌矿相 CdS 混合物的天然生物矿化途径形成鲜明对比。其次，与在天然生物矿化系统中观察到的生长和最终沉淀形成对比，ConK 产生的 CdS 纳米晶体在最终尺寸处稳定。未来使用 ConK 或其他从头设计的蛋白质优化 CdS 纳米晶体生长，可能有助于通过在室温下合成更稳定、高质量的量子点来克服天然生物矿化通常观察到的纳米晶体质量限制。
