Biology subjects

Parra-Saldivar, R.

Publications and source records attributed to Parra-Saldivar, R..

3 recordsLinked to original sources

bioRxiv2024

Immobilized Nucleoside 2'-Deoxyribosyltransferases from Extremophiles for Nucleoside Biocatalysis

The synthesis of nucleosides is crucial for pharmaceutical and biotechnological applications, acting as drugs and as essential building blocks for numerous therapeutic agents. However, most enzymes employed in nucleoside biocatalysis are not recycled, possess limit stability and strict substrate selection for ribonucleosides or 2'deoxyribonucleosides. We employed 2'deoxyribonucleoside transferase (NDT) enzymes from thermophilic and psychrophilic bacteria to demonstrate they can be immobilized to en-hance specific activity, stability, and recyclability. NDT enzymes from Chroococcidiopsis thermalis (CtNDT), and Bacillus psychrosaccharolyticus (BpNDT) were immobilized by covalent attachment to chitosan beads. A double mutant of CtNDT, capable of generating 3'deoxyribonucleosides, showed remarkable and increased stability after immobilization when compared to the same enzyme in solution. Furthermore, we demonstrated the recyclability of immobilized biocatalysts, with a tenfold improvement in reaction yield over 20 consecutive cycles, highlighting the practicality and sustainability of the developed immobilization method. We used our strategy to produce a pharmaceutically relevant 3'deoxyribonucleoside (2-fluoro-3'-deoxyadenosine). This highlights the importance of efficient immobilization techniques to enhance catalytic properties of NDT enzymes, expanding their utility in biocatalysis.

biochemistry↗

bioRxiv2024

Overcoming the challenges of cascade reactions and complex substrates in natural product biocatalysis: Immobilization of a cyclodipeptide synthase.

Cyclodipeptide synthases (CDPSs) use aminoacylated tRNAs to produce cyclic dipeptide natural products which can have anticancer and neuroprotective activity. Despite their potential, applications involving CDPSs are hindered by enzyme instability and challenges in producing aminoacylated tRNAs. Immobilizing enzymes can enhance stability and recyclability, yet studies on immobilized enzymes using aminoacylated tRNAs are lacking. Here, we immobilized the CDPS enzyme from Parcubacteria bacterium RAAC4_OD1_1 (PbCDPS) using three sustainable supports: biochar from waste materials, calcium-alginate beads, and chitosan beads. Active PbCDPS immobilization led to production of the cyclodipeptide cyclo (His-Glu) (cHE). Notably, following activation with glutaraldehyde, a five-fold increase in cHE production was observed, while the immobilized enzyme remained active for seven consecutive cycles. Furthermore, we co-immobilized three enzymes required for the cascade reaction yielding cHE, all of which require aminoacyl-tRNA substrates (PbCDPS, histidyl-tRNA synthetase, and glutamyl-tRNA synthetase). This enzymatic cascade successfully generated the cyclic dipeptide of interest, showcasing the potential of immobilizing complex enzymes operating in cascade on a single support. We demonstrated that tRNAs remained free in solution without adsorption onto beads. This work paves the way for the immobilization of enzymes utilizing tRNAs and potentially other complex substrates, expanding the spectrum of reactions exploitable with this technology. Graphical AbstractO_LIFor Table of Contents Only C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=173 SRC="FIGDIR/small/604810v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@12794baorg.highwire.dtl.DTLVardef@1956c09org.highwire.dtl.DTLVardef@e7f800org.highwire.dtl.DTLVardef@14ac97d_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2019

Integrated biorefinery from Arthrospira platensis biomass as feedstock for bioethanol and lactic acid production

An integrated biorefinery for ethanol and lactic acid production from the biomass of cyanobacterium Arthrospira platensis was investigated. Different pretreatments consisting of supercritical fluid extraction (SFE) and microwave assisted extraction (MAE) with non-polar (MAE-NPS) and polar solvents (MAE-PS) were tested on cyanobacterial biomass to obtain bioactive metabolites and the resulting residual biomass was used as a substrate for fermentation with Saccharomyces cerevisiae LPB-287 and Lactobacillus acidophilus ATCC 43121 to produce ethanol and lactic acid, respectively. The maximum concentrations achieved in our processes were 3.02{+/-}0.07 g/L of ethanol by the MAE-NPS process at 120 rpm 30 {degrees}C, and 9.67{+/-}0.05 g/L of lactic acid by the SFE process at 120 rpm 37 {degrees}C. Our results suggest that the proposed approach can be successfully applied in bioactive metabolites extraction and subsequently in the production of Ethanol and Lactic acid from A. platensis depleted biomass.

microbiology↗