Enzymatic self-assembly/disassembly turns “ON”/“OFF” the mimetic hydrolytic activity of histidine nanofibers

Mimetic enzymes are devised as alternates or supplements of natural enzymes in broad fields but regulating their activities in a switchable manner remains challenging.Herein,we proposed an enzymatic self-assembly/disassembly strategy to address this issue.A peptide molecule Nap FFEYIH(YH) was rationally designed which,after self-assembling into nanofibers,lined up the histidine moieties to form active hydrolysis centers for mimicking hydrolase activity.Enzymatic dephosphorylation of Nap FFEYp IH(Yp H) by alkaline phosphatase to yield YH also turned “ON” the hydrolase activity.In turn,phosphorylation of YH by phosphokinase epidermal growth factor receptor to yield Yp H disassembled the nanofibers and thus turned the activity “OFF”.As such,the “ON”/“OFF” of the mimetic hydrolase activities could be regulated under physiological conditions through ALP/EGFR-mediated self-assembly/disassembly of histidine nanofibers.This work provides a feasible strategy for the on-demand fabrication of artificial enzymes with controllable and superior activities.

Characterization of neutral lipases revealed the tissue-specific triacylglyceroi hydrolytic activity in Nilaparvata lugens

The lipid metabolism plays an essential role in the development andreproduction of insects, and lipases are important enzymes in lipid metabolism. In Nilaparvatalugens, an important insect pest on rice, triacylglycerol hydrolytic activities weredifferent among tissues, with high activity in integument, ovary, and fat body, but low activityin intestine. To figure out the tissue-specific triacylglycerol hydrolytic activity, weidentified 43 lipases in N. lugens. Of these 43 lipases, 23 belonged to neutral lipases, sothis group was selected to perform further experiments on triacylglycerol hydrolysis. Thecomplete motifs of catalytic triads, β9 loop, and lid motif, are required for the triacylglycerolhydrolytic activity in neutral lipases, which were found in some neutral lipases withhigh gene expression levels in integument and ovary, but not in intestine. The recombinantproteins of 3 neutral lipases with or without 3 complete motifs were obtained, and the activitydetermination confirmed the importance of 3 motifs. Silencing XM_022331066.1,which is highly expressed in ovary and with 3 complete motifs, significantly decreasedthe egg production and hatchability of N. lugens, partially through decline of the lipidmetabolism. In summary, at least one-third of important motifs were incomplete in allneutral lipases with high gene expression in intestine, which could partially explain whythe lipase activity in intestine was much lower than that in other tissues. The low activityto hydrolyze triacylglycerol in N. lugens intestine might be associated with its food resourceand nutrient components, and the ovary-specific neutral lipases were important forN. lugens reproduction.

Hydrolytic and Antimicrobial Activities of Bacteria Isolated from Fermented Peppers Sold in Markets at Brazzaville, Republic of the Congo

Microorganisms are omnipresent in all environments and play mainly the role of transformers, thanks to the multiple enzymes they are able to produce. In order to valorize fermented foods in the Republic of the Congo, this work aimed to characterize and study some properties of microorganisms isolated from samples of peppers sold in three markets of Brazzaville. A numeration of the total aerobic mesophilic flora (TAMF) was made in a solid medium, allowing the evaluation of each sample’s microbial concentration. The microbial mass varied from 2.8 × 105 CFU/g for the Ouénzé sample to 1.8 × 104 CFU/g for the Total sample and 2 × 104 CFU/g for the Moungali market sample. The evaluation of the enzymatic properties of the Bacillus isolates showed that 68.42% were capable of producing cellulases and 78.94% were capable of producing amylases and proteases. Antimicrobial activities revealed that 63.15% of the isolates were able to secrete inhibitory substances against E. coli and Staphylococcus aureus. Molecular analysis by PCR amplification, sequencing of the 16S rRNA gene and BLAST bioinformatics analysis provides newly identified bacteria strains with new accession numbers in GenBank: Bacillus thuringiensis MBCBR322 (OP474008), Bacillus megaterium MBCBJ1822 (OP476493), Bacillus thuringiensis MBCBR222 (OP476494), Priestia megaterium MBCBJ2022 (OP476495) and Lactobacillus paraplantarum MBCBR1522 (OP476496). Multiple sequences alignment of identified sequences with their homologs of GenBank has shown high similarities. The phylogenetic inference assay has provided the two groups of strains observed in this study, and the two groups are very coherent with the phylogeny of the reference.

A New Metallomicelle with Hydrolytic Metalloenzymatic Activity

A new metallomicelle, formed by Cu2+ Or Zn2+ ion and N-tetradecyl-2-(N-2-hydroxyethyl aminomethyl) imidazol in the presence of cetyltrimethylammonium bromide, was found to possess remarkable catalytic activity to the hydrolysis of p-nitrophenyl picolinate.

Effects of Lanthanum on Hydrolytic Enzyme Activities in Red Soil

The effects of La on some hydrolytic enzyme activities in red soil were studied in incubation and pot culture experiments. In the incubation experiment, La slightly stimulates the activities of urease and acidic phosphatase in soil and strongly stimulates sucrase activity in soil. In the pot culture experiment, La stimulates the activities of urease, acidic phosphatase and sucrase to different degrees. The stimulative effects of rare earth elements (REE) on hydrolytic enzyme activities in soil may result in increasing yield of crops.

Enzyme-mediated hydrolytic activation of prodrugs

Prodrug design is an important part of drug discovery.Prodrugs can offer many advantages over parent drugs such as increased solubility,enhanced stability,improved bioavailability,reduced side effects,and better selectivity.Many prodrugs have been used successfully in the clinic;examples include oseltamivir in anti-influenza therapy,enalapril in anti-hypertension therapy,capecitabine in cancer therapy,and omeprazole in the treatment of peptic ulcer.A key step in prodrug design is the incorporation of an activation mechanism that can convert the prodrug into the active species in an efficient and/or controlled manner to meet the needs of a given medical application.Prodrug activation can be achieved through enzyme-mediated hydrolytic or oxidoreductive processes while activation of some prodrugs may proceed through pure chemical nonenzymatic processes.This review focuses on the hydrolytic enzymes that have been used in prodrug activation,including transferases,hydrolases,and lyases.