@article{b758e243a7fc41dca4bde26e3cd9816f,
title = "A de novo protein catalyzes the synthesis of semiconductor quantum dots",
abstract = "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 Escherichia coli from otherwise toxic concentrations of copper. ConK was recently found to bind the cofactor PLP (pyridoxal phosphate, the active form of vitamin B6). Here, we show that ConK catalyzes the desulfurization of cysteine to H2S, 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.",
keywords = "binary patterning, biomineralization, de novo, protein design, quantum dots",
author = "Spangler, {Leah C.} and Yueyu Yao and Guangming Cheng and Nan Yao and Chari, {Sarangan L.} and Scholes, {Gregory D.} and Hecht, {Michael H.}",
note = "Funding Information: ACKNOWLEDGMENTS. We thank Dr. Venu Gopal Vandavasi for assistance with the analytical ultracentrifugation measurements performed in the Biophysical Chemistry core facility at the Department of Chemistry, Princeton University. We also thank Dr. John Eng and the Mass Spectrometry core facility. We wish to acknowledge discussions and help from Prof. Wayne Patrick, Victoria University of Wellington, New Zealand. The authors acknowledge the use of Princeton{\textquoteright}s Imaging and Analysis Center, which is partially supported through the Princeton Center for Complex Materials (PCCM), a National Science Foundation (NSF) MRSEC program (DMR-2011750). This work was supported by the NSF grants MCB-1947720 and MCB-1409402 to M.H.H. Additional funding was provided by the Princeton University Writing Center and CIFAR (Canadian Institute for Advanced Research). Dr. Gregory Scholes is CIFAR fellow. Funding Information: We thank Dr. Venu Gopal Vandavasi for assistance with the analytical ultracentrifugation measurements performed in the Biophysical Chemistry core facility at the Department of Chemistry, Princeton University. We also thank Dr. John Eng and the Mass Spectrometry core facility. We wish to acknowledge discussions and help from Prof. Wayne Patrick, Victoria University of Wellington, New Zealand. The authors acknowledge the use of Princeton{\textquoteright}s Imaging and Analysis Center, which is partially supported through the Princeton Center for Complex Materials (PCCM), a National Science Foundation (NSF) MRSEC program (DMR-2011750). This work was supported by the NSF grants MCB-1947720 and MCB-1409402 to M.H.H. Additional funding was provided by the Princeton University Writing Center and CIFAR (Canadian Institute for Advanced Research). Dr. Gregory Scholes is CIFAR fellow. Publisher Copyright: Copyright {\textcopyright} 2022 the Author(s). Published by PNAS.",
year = "2022",
month = dec,
day = "20",
doi = "10.1073/pnas.2204050119",
language = "English (US)",
volume = "119",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
publisher = "National Academy of Sciences",
number = "51",
}