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Background Recombinase (uvsY and uvsX) from bacteriophage T4 is a key enzyme for recombinase polymerase amplification (RPA) that amplifies a target DNA sequence at a constant temperature with a single-stranded DNA-binding protein and a strand-displacing polymerase. The present study was conducted to examine the effects of the N- and C-terminal tags of uvsY on its function in RPA to detect SARS-CoV-2 DNA. Methods Untagged uvsY (uvsY-Δhis), N-terminal tagged uvsY (uvsY-Nhis), C-terminal tagged uvsY (uvsY-Chis), and N- and C-terminal tagged uvsY (uvsY-NChis) were expressed in Escherichia coli and purified. RPA reaction was carried out with the in vitro synthesized standard DNA at 41ºC. The amplified products were separated on agarose gels. Results The minimal initial copy numbers of standard DNA from which the amplified products were observed were 6 ×105, 60, 600, and 600 copies for the RPA with uvsY-Δhis, uvsY-Nhis, uvsY-Chis, and uvsY-NChis, respectively. The minimal reaction time at which the amplified products were observed were 20, 20, 30, and 20 min for the RPA with uvsY-Δhis, uvsY-Nhis, uvsY-Chis, and uvsY-NChis, respectively. The RPA with uvsY-Nhis exhibited clearer bands than that with either of other three uvsYs. Conclusion The reaction efficiency of RPA with uvsY-Nhis was the highest, suggesting that uvsY-Nhis is suitable for use in RPA.

Background Recombinase (uvsY and uvsX) from bacteriophage T4 is a key enzyme for recombinase polymerase amplification (RPA) that amplifies a target DNA sequence at a constant temperature with a single-stranded DNA-binding protein and a strand-displacing polymerase. The present study was conducted to examine the effects of the N- and C-terminal tags of uvsY on its function in RPA to detect SARS-CoV-2 DNA. Methods Untagged uvsY (uvsY-Δhis), N-terminal tagged uvsY (uvsY-Nhis), C-terminal tagged uvsY (uvsY-Chis), and N- and C-terminal tagged uvsY (uvsY-NChis) were expressed in Escherichia coli and purified. RPA reaction was carried out with the in vitro synthesized standard DNA at 41 °C. The amplified products were separated on agarose gels. Results The minimal initial copy numbers of standard DNA from which the amplified products were observed were 6 × 105, 60, 600, and 600 copies for the RPA with uvsY-Δhis, uvsY-Nhis, uvsY-Chis, and uvsY-NChis, respectively. The minimal reaction time at which the amplified products were observed were 20, 20, 30, and 20 min for the RPA with uvsY-Δhis, uvsY-Nhis, uvsY-Chis, and uvsY-NChis, respectively. The RPA with uvsY-Nhis exhibited clearer bands than that with either of other three uvsYs. Conclusions The reaction efficiency of RPA with uvsY-Nhis was the highest, suggesting that uvsY-Nhis is suitable for use in RPA. Supplementary Information The online version of this article contains supplementary material available 10.1007/s11033-021-07098-y.

We have previously reported the effective catalytic decomposition of volatile organic compounds (VOCs) using stoichiometric hydroxyapatite (HAp), making it the most promising alternative catalyst to replace the expensive conventional noble-metal nanoparticles for VOC purification. Here we derive a catalysis mechanism by exploring HAps with various Ca/P molar ratios (1.70, 1.67, 1.57, 1.37) for the catalytic decomposition of VOCs (ethyl acetate, isopropanol, acetone). In particular, the mechanism is discussed with respect to the particle morphology, specific surface area, crystallinity, chemical structure, radical generation, in situ VOC adsorption properties and acidic/basic site population of HAps combined with confirmation of decomposed by-products in different VOCs. The achieved nearly complete decomposition (98.04%) of VOCs and the initially established catalysis mechanism demonstrated in this work not only provide principle information for catalysis science and technology, but also open a new possibility for the design of noble-metal-free catalysts towards environmental cleaning.