Efficient CO2-Reducing Activity of NAD-Dependent Formate Dehydrogenase from Thiobacillus sp KNK65MA for Formate Production from CO2 Gas

NAD-dependent formate dehydrogenase (FDH) from Candida boidinii (CbFDH) has been widely used in various CO2 reduction systems but its practical applications are often impeded due to low CO2-reducing activity. In this study, we demonstrated superior CO2-reducing properties of FDH from Thiobacillus sp. KNK65MA (TsFDH) for production of formate from CO2 gas. To discover more efficient CO2-reducing FDHs than a reference enzyme e. CbFDH, five FDHs were selected with biochemical properties and then, their CO2-reducing activities were evaluated. All FDHs including CbFDH showed better CO2-reducing activities at acidic pHs than at neutral pHs and four FDHs were more active than CbFDH in the CO2 reduction reaction. In particular, the FDH from Thiobacillus sp. KNK65IVIA (TsFDH) exhibited the highest CO2-reducing activity and had a dramatic preference for the reduction reaction, i.e., a 84.2-fold higher ratio of CO2 reduction to formate oxidation in catalytic efficiency (k(cat)/K-B) compared to CbFDH. Formate was produced from CO2 gas using TsFDH and CbFDH, and TsFDH showed a 5.8-fold higher formate production rate than CbFDH. A sequence and structural comparison showed that FDHs with relatively high CO2-reducing activities had elongated N- and C-terminal loops. The experimental results demonstrate that TsFDH can be an alternative to CbFDH as a biocatalyst in CO2 reduction systemsope

Carbon Dioxide Utilisation -The Formate Route

UIDB/50006/2020 CEEC-Individual 2017 Program Contract.The relentless rise of atmospheric CO2 is causing large and unpredictable impacts on the Earth climate, due to the CO2 significant greenhouse effect, besides being responsible for the ocean acidification, with consequent huge impacts in our daily lives and in all forms of life. To stop spiral of destruction, we must actively reduce the CO2 emissions and develop new and more efficient “CO2 sinks”. We should be focused on the opportunities provided by exploiting this novel and huge carbon feedstock to produce de novo fuels and added-value compounds. The conversion of CO2 into formate offers key advantages for carbon recycling, and formate dehydrogenase (FDH) enzymes are at the centre of intense research, due to the “green” advantages the bioconversion can offer, namely substrate and product selectivity and specificity, in reactions run at ambient temperature and pressure and neutral pH. In this chapter, we describe the remarkable recent progress towards efficient and selective FDH-catalysed CO2 reduction to formate. We focus on the enzymes, discussing their structure and mechanism of action. Selected promising studies and successful proof of concepts of FDH-dependent CO2 reduction to formate and beyond are discussed, to highlight the power of FDHs and the challenges this CO2 bioconversion still faces.publishersversionpublishe

Production asymmetry of D-s from 600 GeV/c Sigma(-) and pi(-) beam

The production of D-S(-) relative to D-S(+) as a function of x(F) with 600 GeV/c Sigma(-) beam is measured in the interval 0.15 < x(F) < 0.7 by the SELEX (E781) experiment at Fermilab. The integrated charge asymmetries with 600 GeV/c Sigma(-) beam (0.53 +/- 0.06) and pi(-) beam (0.06 +/- 0.11) are also compared. The results show the Sigma(-) beam fragments play a role in the production of D-S(-), as suggested by the leading quark model. (C) 2003 Elsevier Science B.V. All rights reserved

First measurement of pi(-)e ->pi(-)e gamma pion virtual compton scattering

Pion virtual compton scattering (VCS) via the reaction pi(-)e-->pi(-)egamma was observed in the Fermilab E781 SELEX experiment. SELEX used a 600 GeV/c pi(-) beam incident on target atomic electrons, detecting the incident pi(-) and the final state pi(-), electron and gamma. Theoretical predictions based on chiral perturbation theory are incorporated into a Monte Carlo simulation of the experiment and are compared to the data. The number of reconstructed events (=9) and their distribution with respect to the kinematic variables (for the kinematic region studied) are in reasonable accord with the predictions. The corresponding pi(-) VCS experimental cross section is sigma=38.8+/-13 nb, in agreement with the theoretical expectation of sigma=34.7 nb

Measurement of the D-s(+/-) lifetime

We report a precise measurement of the D-s(+/-) meson lifetime. The data were taken by the SELEX experiment (E781) spectrometer using 600 GeV/c Sigma (-), pi (-) and p beams. The measurement has been done using 918 reconstructed D-s(+/-). The lifetime of the D-s(+/-) s is measured to be 472.5 +/- 17.2 +/- 6.6 fs, using K*(892)K-0(+/-) and phi pi (+/-) decay modes. The lifetime ratio of D-s(+/-) to D-0 is 1.145 +/- 0.049. (C) 2001 Elsevier Science B.V. All rights reserved

First observation of the doubly charmed baryon Xi(+)(cc)

We observe a signal for the doubly charmed baryon Xi(cc)(+) in the charged decay mode Xi(cc)(+)-->Lambda(c)(+)K(-)pi(+) in data from SELEX, the charm hadroproduction experiment at Fermilab. We observe an excess of 15.9 events over an expected background of 6.1+/-0.5 events, a statistical significance of 6.3sigma. The observed mass of this state is 3519+/-1 MeV/c(2). The Gaussian mass width of this state is 3 MeV/c(2), consistent with resolution; its lifetime is less than 33 fs at 90% confidence

Hadronic production of Lambda c from 600 GeV/c pi(-), Sigma(-) and p beams

We present data from Fermilab experiment E781 (SELEX) on the hadroproduction asymmetry for (Lambda) over bar((c)) over bar compared to Lambda(c)(+) as a function of x(F), and on p(t)(2) distributions for Lambda(c)(+). These data were measured in the same apparatus using incident pi(-),Sigma(-) beams at 600 GeV/c and proton beam at 540 GeV/c. The asymmetry is studied as a function of x(F). In the forward hemisphere with x(F) greater than or equal to 0.2 both baryon beams exhibit very strong preference for producing charm baryons rather than charm antibaryons, while the pion beam asymmetry is much smaller. In this energy regime the results show that beam fragments play a major role in the kinematics of Lambda(c) formation, as suggested by the leading quark picture. (C) 2002 Published by Elsevier Science B.V