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 B 6 ). Here, we show that ConK catalyzes the desulfurization of cysteine to H 2 S, 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.

Selection of ade novogene that can promote survival ofE. coliby modulating protein homeostasis pathways

“…Another random protein was found to promote survival in high concentrations of copper 67 , but the underlying molecular mechanism remains unknown. This random protein was also studied in vitro and found to catalyze the conversion of cysteine to H 2 S in a pyridoxal phosphate dependent manner 20 .…”

“…A complementary approach to investigating de novo gene birth involves the characterization of randomly generated proteins and studying whether they can benefit cells. Prior work has examined in silico and in vitro properties of such random sequences, including their predicted ability to fold into secondary structures 16 , solubility 17 , ATPase activity 18 , or potential affinity for different molecules [19][20][21][22] . However, cellular functions for random genes have rarely been demonstrated in vivo.…”

Understanding Biomineralization Mechanisms to Produce Size-Controlled, Tailored Nanocrystals for Optoelectronic and Catalytic Applications: A Review

“…Recently, Spangler et al identified a de novo protein that was capable of producing CdS quantum dots with size tunable properties. 114 De novo proteins stand in stark contrast to natural proteins as they are not found in nature, and instead are designed following a polar-non polar amino acid motif. Thus, de novo proteins are not expected to have any functionality.…”

New opportunities for astronomical imaging systems

“…Other manufacturing methods are being developed. For example, Spangler et al (2022) have developed new quantum dot manufacturing processes involving new synthetic proteins that avoid much of the use of toxic materials that also allow manufacturing of the dots to be at room temperature. When a photon is absorbed, a carrier is excited from the valence band to the conduction band in the nano‐crystal.…”