Polyethylene glycol crowding effect on hyaluronidase activity monitored by capillary electrophoresis

Non-ionic surfactant PEG: Enhanced cutinase-catalyzed hydrolysis of polyethylene terephthalate

To enhance the enzymatic digestibility of polyethylene terephthalate (PET), which is highly oriented and crystallized, a polyethylene glycol (PEG) surfactant of varying molecular weights was utilized to improve the stability of mutant cutinase from Humicola insolens (HiC) and to increase the accessibility of the enzyme to the substrate. Leveraging the optimal conditions for HiC hydrolysis of PET, the introduction of 1 % w/v PEG significantly increased the yield of PET hydrolysis products. PEG600 was particularly effective, increasing the yield by 64.58 % compared to using HiC alone. Moreover, the mechanisms by which PEG600 and PEG6000 enhance enzyme digestion were extensively examined using circular dichroism and fluorescence spectroscopy. The results from CD and fluorescence analyses indicated that PEG alters the protein conformation, thereby affecting the catalytic effect of the enzyme. Moreover, PEG improved the affinity between HiC and PET by lowering the surface tension of the solution, substantially enhancing PET hydrolysis. This study suggests that PEG holds considerable promise as an enzyme protector, significantly aiding in the hydrophilic modification and degradation of PET in an environmentally friendly and sustainable manner.

Screening for pancreatic lipase natural modulators by capillary electrophoresis hyphenated to spectrophotometric and conductometric dual detection

The search for novel pancreatic lipase (PL) inhibitors has gained increasing attention in recent years. For the first time, a dual detection capillary electrophoresis (CE)-based homogeneous lipase assay was developed employing both the offline and online reaction modes. The hydrolysis of 4-nitrophenyl butyrate (4-NPB) catalyzed by PL into 4-nitrophenol and butyrate was monitored by spectrophotometric and conductimetric detection, respectively. The assays presented several advantages such as economy in consumption (few tens of nanoliters for online assays to few tens of microliters for offline assays), no modification of lipase, rapidity (<10 min) and versatility. Tris/MOPS (10 mM, pH 6.6) was used as the background electrolyte and the incubation buffer for enzymatic reactions. We confirmed that in the conditions of the study (small substrate 4-NPB, 37 °C, pH 6.6), the PL was active even in the absence of dipalmitoylphosphatidylcholine (DPPC) vesicles, generally used to mimic the lipid-water interface. This was confirmed by the maximum velocity (Vmax) and the Michaelis-Menten constant (Km) values that were the same order of magnitude in the absence and presence of DPPC. The developed method was used to screen crude aqueous plant extracts and purified compounds. We were able to identify the promising PL inhibition of hawthorn leaf herbal infusions at 1 mg mL-1 (37%) and PL activation by fresh and dry hawthorn flowers (∼24%). Additionally, two triterpenoids purified from extracts of oakwood were identified for the first time as potent PL inhibitors demonstrating 51 and 58% inhibition at 1 mg mL-1, respectively.

Kinetic theory of hyaluronan cleavage by bovine testicular hyaluronidase in standard and crowded environments

In this paper, we introduce a comprehensive kinetic model describing the enzymatic cleavage of hyaluronan (HA) by bovine testicular hyaluronidase (BTH). Our theory focuses specifically on the late stage of the hydrolysis, where the concentrations of a limited number of oligomers may be determined experimentally with accuracy as functions of time. The present model was applied to fit different experimental sets of kinetic data collected by capillary electrophoresis at two HA concentrations and three concentrations of PEG crowder (0, 10, 17% w/w). Our theory seems to apply universally, irrespective of HA concentration and crowding conditions, reproducing to an excellent extent the time evolution of the individual molar fractions of oligomers. Remarkably, we found that the reaction mechanism in the late degradation stage essentially reduces to the cleavage or transfer of active dimers. While the recombination of dimers is the fastest reaction, the rate-limiting step turns out to be invariably the hydrolysis of hexamers. Crowding, HA itself or other inert, volume-excluding agents, clearly boosts recombination events and concomitantly slows down all fragmentation pathways. Overall, our results bring a novel and comprehensive quantitative insight into the complex reaction mechanism underlying enzymatic HA degradation. Importantly, rationalizing the effect of crowding not only brings the intricate conditions of in-vivo settings a little closer, but also emerges as a powerful tool to help pinpointing relevant kinetic pathways in complex systems.

Water-Based Extraction of Bioactive Principles from Blackcurrant Leaves and Chrysanthellum americanum: A Comparative Study

The water-based extraction of bioactive components from flavonoid-rich medicinal plants is a key step that should be better investigated. This is especially true when dealing with easy-to-use home-made conditions of extractions, which are known to be a bottleneck in the course for a better control and optimization of the daily uptake of active components from medicinal plants. In this work, the water-based extraction of Blackcurrant (Ribes nigrum) leaves (BC) and Chrysanthellum americanum (CA), known to have complementary pharmacological properties, was studied and compared with a previous work performed on the extraction of Hawthorn (Crataegus, HAW). Various extraction modes in water (infusion, percolation, maceration, ultrasounds, microwaves) were compared for the extraction of bioactive principles contained in BC and CA in terms of extraction yield, of amount of flavonoids, phenolic compounds, and proanthocyanidin oligomers, and of UHPLC profiles of the extracted compounds. The qualitative and quantitative aspects of the extraction, in addition to the kinetic of extraction, were studied. The optimized easy-to-use-at-home extraction protocol developed for HAW was found very efficient to easily extract bioactive components from BC and CA plants. UHPLC-ESI-MS and high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) were also implemented to get more qualitative information on the specific and common chemical compositions of the three plants (including HAW). Their antihyaluronidase, antioxidant, and antihypertensive activities were also determined and compared, demonstrating similar activities as the reference compound for some of these plants.