Open Access

Peptidyl-lys metalloendopeptidases (PKMs) are enzymes that selectively cleave peptide bonds at the N-terminus of lysine residues present in the P1′ position, making them valuable tools in proteomics. This mini-review presents an overview of PKMs, covering their traditional production from native sources, recent advances in recombinant production, and the current limitations in availability. The historical and current applications of PKMs in proteomics are discussed, highlighting their role in protein sequencing, peptide mapping, and mass spectrometry-based studies. Advances in recombinant technology now enable tailored modifications to PKM, allowing it to function not only as a sister enzyme to LysC but also to trypsin, thereby enhancing its suitability for specific analytical applications. The mini-review concludes with a forward-looking statement on PKM research, emphasizing the potential to broaden its use in novel proteomic methods and other applications.

Redox-active biochars can enhance contaminant transformation in persulfate-based Fenton-like water treatment by facilitating Fe(III) reduction to Fe(II). However, biochar properties vary greatly depending on both feedstock selection and pyrolysis conditions. Best suited biochars for Fe(III) reduction and persulfate activation have yet to be identified. Here, we investigated eight biochars for their ability to activate persulfate with Fe(III) to transform N,N-diethyl-m-toluamide (DEET) in water. Four of the biochars were produced from beech wood under different pyrolysis conditions (450–750 °C, high and low nitrogen flow rate in the reactor) and four biochars were produced from softwood amended with 0 – 43 weight percent (wt%) wood ash prior to pyrolysis at 500 °C. Beech wood biochar produced at 450 °C transformed DEET most efficiently with a half-life time of 39 ± 4 min, likely due to the high concentration of surface oxygen functional groups and persistent free radicals that accelerated Fe(III) reduction and formation of reactive species. Among the ash-amended biochars, biochar with 16 wt% ash amendment showed the most efficient DEET transformation with a half-life time of 27 ± 0.6 min, which is 10-times faster compared to a non-ash-amended biochar produced from the same biomass under similar pyrolysis conditions. Ash amendment led to the formation of crystalline iron minerals in biochars, which likely promoted Fe(III) reduction and persulfate activation. Our results highlight the potential for fine-tuning the redox properties of biochar, e.g., by ash amendment to a woody feedstock, enabling tailored performance for specific water treatment applications.

The research for plastic alternatives is one of the most important recent fields in organic and polymer chemistry, aiming to develop novel materials for a more sustainable future. As humans impact even the most remote places on earth, pollution due to the accumulation of synthetic polymers is the witness of this devastating dynamic. However, promising biomass derived polymers have been discovered, showing the potential to replace fossil-based plastics efficiently. Nevertheless, only a small number of bio-based materials having comparable properties with their petrol-based counterparts are available nowadays. Intending to enlarge the knowledge on the possible renewable, recyclable, and/or biodegradable polymer materials, developing alternative methods and synthetic routes are indispensable. The chemo-enzymatic synthesis of polymers derived from itaconic acid (IA) represents a novel route amongst the various possible alternative paths of polymer synthesis and production. IA and its diester, dimethyl itaconate (DMI), have received a lot of interest as a new chemical building block since it is biotechnologically generated from carbohydrates on a large scale. Their trifunctional structures enable the production of novel polymers such as poly(itaconates), related copolymers, and derived monomers for polycondensation such as the herein described bispyrrolidone (BP) structures, dimethyl 2-((diethylamino)methyl)succinate (DAMS) and dimethyl 2-((octylthio)methyl)succinate (DOMS). This thesis elucidates, for the first time, the use of BP and DOMS as monomers for enzymatically catalyzed polymerization reactions. Novel BP monomers were prepared from reactions between renewable DMI and various aliphatic diamines. These BP monomers were synthesized with high conversions and purity showing versatility as monomer for polycondensation and as plasticizing additives in polymer blends with poly(lactic acid) (PLA). In particular, the monomers and new polyesters obtained by their polycondensation demonstrated remarkable thermal stability. Being a rather new field of research, polyesters generated from unsaturated acids like IA have only just begun to receive attention, despite a wide range of possible uses, including UV-curing resins for coatings, inks or adhesives, and thermally curing compositions, to mention a few. Establishing ecofriendly synthesis routes, combining the various tools available and theoretical organic chemistry, is an important step to allow the development of more sustainable synthesis and work-up procedures in the polymer industry. Within this project, further investigation into the synthesis and the potential of itaconate-based polyesters is described. The BP monomers synthesis and polymerization (using an immobilized enzyme) creating novel bio-based polyesters is particularly highlighted.