Catalytic action of alternansucrase on sucrose under in vitro simulated gastric conditions.

Alternansucrase, a glucosyltransferase, is currently used to produce slowly digestible alternan oligosaccharides or maltooligosaccharides from sucrose. These oligosaccharides are popular for food fortification to lower postprandial glucose levels. This study aimed to explore the enzymatic reaction of alternansucrase in simulated in vitro gastric reaction conditions. Under the studied conditions, SucroSEB (a model enzyme for alternansucrase) hydrolyzed the sucrose and transglycosylated the glucose to produce glucans, both in the absence and presence of acceptors. The preference of the acceptor was maltose˃ raffinose˃ lactose. The rate of sucrose hydrolysis was significantly higher in the presence of maltose (p = 0.024). The glucans formed during the reaction included oligomers (DP 3-10) and polymers (DP ≥ 11), both of which increased over time. These glucans contained α-1,3 and α-1,6 glycosidic linkages, confirmed by 1H and 13C NMR. They were slowly and partially digestible in the presence of rat intestinal extract in contrast to the complete and rapid digestion of starch. The glucans formed after a longer gastric reaction time exhibited higher dietary fiber potential (19.145 ± 4.77 %; 60 min) compared to those formed during the initial phase (2.765 ± 0.19 %; 15 min). Overall, this study demonstrated the efficacy of SucroSEB in converting sucrose to slowly and partially digestible glucans under simulated in vitro gastric conditions.

In vitro simulated study of macronutrient digestion in complex food using digestive enzyme supplement.

Digestive enzymes secreted by the body are vital for digestion and nutrient absorption. Enzyme supplements are commonly used to support them in achieving optimal digestion. Herein, the efficacy of digestive enzyme supplement (DigeSEB Super) in digestion of complex food was assessed using INFOGEST simulated static and modified semi-dynamic in vitro digestion models. Digestive enzyme supplement was found to assist the endogenous digestive enzymes to disintegrate the food matrix. Hence, it reduced the viscosity of the gastric digesta by 2.75 fold (p = 0.04) compared to the control digestion (only endogenous digestive enzymes) during the first hour of digestion. Similarly, enzyme supplement showed statistically higher release of reducing sugars in the gastric digestion (p ≤ 0.05) indicating improved digestion of carbohydrates. Further, digestion of proteins and fats was also improved in the presence of enzyme supplement. The kinetic aspects of the semi-dynamic model (transient nature of gastric secretions and gradual acidification) was found to alter the macronutrient digestion compared to the static digestion. Thus, semi-dynamic model should be preferred for the in vitro studies. Overall, current study demonstrated the potential of a digestive enzyme supplement to improve digestion by aiding digestive action of the endogenous enzymes.

Mechanoresponsive and recyclable biocatalytic sponges from enzyme-polymer surfactant conjugates and nanoparticles.

The development of multifunctional hybrid biomaterials is an important area of focus in tissue engineering, drug delivery, biocatalysis, and biosensing applications. Combining bioconjugation methodology with ice templating technique, we show here the development of a new class of multifunctional and biocatalytic scaffold-like spongy material fabricated from an aqueous solution of enzyme-polymer surfactant (enzyme-PS) core-shell conjugates, and polyethyleneimine (PEI) coated silica/silk nanoparticles. The generality of this process is demonstrated by the fabrication of biocatalytic sponges comprising PEI coated nanoparticles and core-shell conjugates of alkaline phosphatase (ALP-PS), or glucose oxidase (GOx-PS), and horseradish peroxidase (HRP-PS). We show that ALP-PS conjugate driven biocatalytic transformations can be simply achieved by saturating the highly porous, and manoeuvrable sponges with the p-nitrophenyl phosphate substrate solution. Subsequently, the compressible and elastic property of the sponge can be utilized for the extrusion of the product, p-nitrophenol, by applying controlled and normal mechanical stress. Further, the sponges can be washed and recycled upto ten times, with approximately 67% retention of initial biocatalytic activity. Interestingly, the ALP-PS conjugate based sponges exhibit mechanoresponsive catalytic behaviour; the amount of product obtained over 25 minutes of reaction time can be increased by approx. 8 times by compressing-decompressing the sponge after every 15 seconds. This is attributed to the change in mass transfer and diffusion of the substrate within the porous channels of the sponge. We also highlight the importance of bioconjugation of enzymes for fabricating such sponges; our results show that, whilst the native enzymes either denature or are leached away during the fabrication/biocatalytic usage, their enzyme-PS conjugate counterparts integrate efficiently to form sturdy, robust, highly catalytic, and recyclable sponge material.