A fast, miniaturised in-vitro assay developed for quantification of lipase enzyme activity

pH-dependent electrostatic interactions between enzymes and nanoparticles in Pickering emulsions - Influence on activity and droplet size

Pickering emulsions (PE) are liquid-liquid systems that are stabilized by solid (nano)particles at the fluid interface. They offer higher stability, easier separation and lower toxicity compared to classical emulsions stabilized by surfactants. Common applications range from food science to drug delivery. In the last decade they have become of more interest in the field of multiphasic biocatalysis. First, this study aims to present the influence of pH, salt strength and particle charge on enzyme activity. The different behavior of two lipases (CaLA and CRL) is shown. While the activity optimum of CaLA changed from pH 6.5 to pH 5 by applying particles with negative instead of positive surface charge, the CRL activity optimum stayed at pH 5-5.5. This enables particle charge as an additional parameter to optimize biocatalytic reactions in PEs. Second, the resulting drop sizes were measured to elucidate further interactions between the enzymes and particles in PEs. Drop sizes in PEs prepared with CaLA were not influenced by pH, but increased for positively and decreased for negatively charged particles upon the addition of CaLA. Electrostatic attraction between particles and CRL increased the droplet diameter from 10 μm up to 30 μm and therefore destabilized the PE for both particle types.

Exogenous lipase administration alters gut microbiota composition and ameliorates Alzheimer's disease-like pathology in APP/PS1 mice

Alzheimer's disease (AD) represents the most common form of dementia in the elderly with no available disease modifying treatments. Altered gut microbial composition has been widely acknowledged as a common feature of AD, which potentially contributes to progression or onset of AD. To assess the hypothesis that Candida rugosa lipase (CRL), which has been shown to enhance gut microbiome and metabolite composition, can rebalance the gut microbiome composition and reduce AD pathology, the treatment effects in APPswe/PS1de9 (APP/PS1) mice were investigated. The analysis revealed an increased abundance of Acetatifactor and Clostridiales vadin BB60 genera in the gut; increased lipid hydrolysis in the gut lumen, normalization of peripheral unsaturated fatty acids, and reduction of neuroinflammation and memory deficits post treatment. Finally, we demonstrated that the evoked benefits on memory could be transferred via fecal matter transplant (FMT) into antibiotic-induced microbiome-depleted (AIMD) wildtype mice, ameliorating their memory deficits. The findings herein contributed to improve our understanding of the role of the gut microbiome in AD's complex networks and suggested that targeted modification of the gut could contribute to amelioration of AD neuropathology.

Novel, natural allosteric inhibitors and enhancers of Candida rugosa lipase activity

Candida rugosa lipase (CRL) is an enzyme commonly used in medicinal and biotechnological applications. Allosteric modulators of CRL could aid in modifying lipase-related diseases as well as improving biotechnological processes. Thus, a combinatorial approach of computational in-silico and high-throughput in-vitro screening was used to identify allosteric modulators of CRL. The screening of natural product libraries resulted in 132 compounds of which 53 were tested in-vitro. Subsequently, four inhibitors and three enhancers were identified of which rutin and cynaroside represented the strongest inhibitors of CRL activity (IC50: 227 ± 26 µM and 446 ± 15 µM, respectively) and NP-008496 the strongest enhancer (EC50: 425 ± 18 µM). All three compounds were predicted to bind the same allosteric site suggesting a common mechanism. Therefore, the present study demonstrated a reliable work-flow, identified an allosteric site of CRL and determined inhibitors and enhancers with numerous potential medical and biotechnological applications.

Candida rugosa lipase alters the gastrointestinal environment in wild-type mice

Diet and commercially available supplements can significantly impact the gut microbial composition; however, the effects of supplements often lack scientific data demonstrating the effects on healthy and diseased individuals. Hence, it was investigated, whether a frequently used supplement in humans, Candida rugosa lipase (CRL), gets delivered active beyond the stomach in the intestinal tract of C57BL/6 J mice and its impact on the gut microbial community and environment. We showed for the first time the movement of CRL in an active state through the mouse digestive tract by determination of intestinal CRL activity and free fatty acids concentrations. The short- and long-term administration of CRL resulted in significant alterations of the gut microbiome, favoring the growth of, for instance, Verrucomicrobia but also other species associated with normal body mass index (BMI) or butyrate expression, both considered beneficial. In addition, we showed that these changes persisted after supplementation and that gut barrier integrity was unaffected by the treatment. In conclusion, CRL can be delivered in an active state beyond the stomach and supplementation altered the murine gut microbiome favoring beneficial bacterial species, which may be of relevance in humans in healthy but also potentially in disease states.