Now it is well recognized that the microRNA (miRNA) expression is altered in response to internal (developmental or hormonal) or external stimuli such as biotic and abiotic stresses in plants. It is also known that several miRNAs are induced in response to deficiency of specific nutrients within the plant or in the external sources, i.e., soil/nutrient media. For instance, P-deprivation induces...

Catechols are found in nature taking part in a remarkably broad scope of biochemical processes and functions. Though not exclusively, such versatility may be traced back to several properties uniquely found together in the o -dihydroxyaryl chemical function; namely, its ability to establish reversible equilibria at moderate redox potentials and pHs and to irreversibly cross-link through complex...

Monitoring spatial distribution of metabolites in multicellular structures can enhance understanding of the biochemical processes and regulation involved in cellular community development. Here we report on an electrochemical camera chip capable of simultaneous spatial imaging of multiple redox-active phenazine metabolites produced by Pseudomonas aeruginosa PA14 colony biofilms. The chip featur...

Transient complexes, with a lifetime ranging between microseconds and seconds, are essential for biochemical reactions requiring a fast turnover. That is the case of the interactions between proteins engaged in electron transfer reactions, which are involved in relevant physiological processes such as respiration and photosynthesis. In the latter, the copper protein plastocyanin acts as a solub...

Extracts of rabbit liver and brain are known (1, 2) to oxidize pyridoxine 5-phosphate to pyridoxal 5-phosphate much faster than they oxidize free pyridoxine to pyridoxal. Comparison of the two activities during limited purification indicated that different enzymes catalyzed the two reactions (1). Pogell (3) had shown previously that oxidation of pyridoxamine 5-phosphate was catalyzed by an enzy...

Molecular dynamics (MD) simulations have been performed on the regulatory domain of the Escherichia coli OxyR transcription factor for the different chemical states along the mechanistic cycle for its activation by hydrogen peroxide. Conformational analysis indicates that His198 and Arg220 catalytic residues can be involved in the biochemical process of activation of OxyR. On the basis of the s...

Nature utilizes oxido-reductases to cater to the energy demands of most biochemical processes in respiratory species. Oxido-reductases are capable of meeting this challenge by utilizing redox active sites, often containing transition metal ions, which facilitate movement and relocation of electrons/protons to create a potential gradient that is used to energize redox reactions. There has been a...

Ascorbic acid (AA), a potent antioxidant readily scavenging reactive species, is a crucial micronutrient involved in many biochemical processes. Here, we have developed a cobalt oxyhydroxide (CoOOH)-modified upconversion nanosystem for fluorescence sensing of AA activity in human plasma. The nanosystem consists of upconversion nanoparticles (UCNPs) NaYF4:30% Yb,0.5% Tm@NaYF4, which serve as ene...

The presence of an Fe(V)(O) species has been postulated as the active intermediate for the oxidation of both C-H and C═C bonds in the Rieske dioxygenase family of enzymes. Understanding the reactivity of these high valent iron-oxo intermediates, especially in an aqueous medium, would provide a better understanding of these enzymatic reaction mechanisms. The formation of an Fe(V)(O) complex at r...

A sensitive and convenient electrochemical assay of plasmin activity and its kinetic analysis are described. Thus, a ferrocenyl peptide substrate (FcPS) having a plasmin-specific substrate sequence, Lys-Thr-Phe-Lys, and a Cys residue was prepared and immobilized on a gold electrode through the sulfur-gold linkage. The obtained electrode showed a redox signal based on the ferrocene moiety, sugge...