Interaction of Dehydrogenase Enzymes with Nanoparticles in Industrial and Medical Applications, and the Associated Challenges: A Mini-review.

BACKGROUND: Nanoparticles (NPs) are a group of particles with at least one dimension ranging from 1 nm to 100 nm in diameter and a surrounding interfacial layer. The NP-protein interactions include covalent and non-covalent bonds. Several dehydrogenase enzymes (e.g., alcohol dehydrogenase, lactate dehydrogenase, alanine dehydrogenase, glutamate dehydrogenase, leucine dehydrogenase, phenylalanine dehydrogenase, and malate dehydrogenase) are used for immobilization by NPs. Also, magnetic NPs and quantum dots are promising model systems for the design of bioanalytical sensors and biological enzyme assemblies. In this overview, we aimed to improve the current knowledge of interactions between dehydrogenase enzymes and NPs and to introduce dehydrogenases with industrial and medical applications. Also, bioconjugation of NPs with dehydrogenase enzymes has broad applications in biocatalysis and nanomedicine in the field of drug discovery. However, studies on the characterization of NP-enzyme complexes show that the anatomy and activity of enzymes are dependent on the chemistry of NP ligands, NP size, and labeling methods. Moreover, the NPprotein conjugates show increased/decreased enzymatic activities, depending on the NP features. CONCLUSION: In this study, we reviewed the findings related to NP-enzyme interactions for nanotechnology applications and conjugation techniques. We also highlighted several challenges associated with the NP-enzyme interactions, including the stability and reusability of enzymes in NP-enzyme formation.

Highly toxic Microcystis aeruginosa strain, isolated from São Paulo-Brazil, produce hepatotoxins and paralytic shellfish poison neurotoxins.

While evaluating several laboratory-cultured cyanobacteria strains for the presence of paralytic shellfish poison neurotoxins, the hydrophilic extract of Microcystis aeruginosa strain SPC777--isolated from Billings's reservoir, São Paulo, Brazil--was found to exhibit lethal neurotoxic effect in mouse bioassay. The in vivo test showed symptoms that unambiguously were those produced by PSP. In order to identify the presence of neurotoxins, cells were lyophilized, and the extracts were analyzed by HPLC-FLD and HPLC-MS. HPLC-FLD analysis revealed four main Gonyautoxins: GTX4(47.6%), GTX2(29.5%), GTX1(21.9%), and GTX3(1.0%). HPLC-MS analysis, on other hand, confirmed both epimers, with positive Zwitterions M(+) 395.9 m/z for GTX3/GTX2 and M(+) 411 m/z for GTX4/GTX1 epimers.The hepatotoxins (Microcystins) were also evaluated by ELISA and HPLC-MS analyses. Positive immunoreaction was observed by ELISA assay. Alongside, the HPLC-MS analyses revealed the presence of [L: -ser(7)] MCYST-RR. The N-methyltransferase (NMT) domain of the microcystin synthetase gene mcyA was chosen as the target sequence to detect the presence of the mcy gene cluster. PCR amplification of the NMT domain, using the genomic DNA of the SPC777 strain and the MSF/MSR primer set, resulted in the expected 1,369 bp product. The phylogenetic analyses grouped the NMT sequence with the NMT sequences of other known Microcystis with high bootstrap support. The taxonomical position of M. aeruginosa SPC777 was confirmed by a detailed morphological description and a phylogenetic analysis of 16S rRNA gene sequence. Therefore, co-production of PSP neurotoxins and microcystins by an isolated M. aeruginosa strain is hereby reported for the first time.