Gelatin and Starch: What Better Stabilizes the Enzyme Activity?

Enzymes Immobilized into Starch- and Gelatin-Based Hydrogels: Properties and Application in Inhibition Assay

The present work is a review of the research on using hydrogels based on natural biodegradable polymers, starch, and gelatin for enzyme immobilization. This review addresses the main properties of starch and gelatin that make them promising materials in biotechnology for producing enzyme preparations stable during use and storage and insensitive to chemical and physical impacts. The authors summarize their achievements in developing the preparations of enzymes immobilized in starch and gelatin gels and assess their activity, stability, and sensitivity for use as biorecognition elements of enzyme inhibition-based biosensors.

Immobilization of Firefly Bioluminescent System: Development and Application of Reagents

The present study describes the method of preparing reagents containing firefly luciferase (FLuc) and its substrate, D-luciferin, immobilized into gelatin gel separately or together. The addition of stabilizers dithiothreitol (DTT) and bovine serum albumin (BSA) to the reagent is a factor in achieving higher activity of reagents and their stability during storage. The use of immobilized reagents substantially simplifies the procedure of assay for microbial contamination. The mechanism of action of the reagents is based on the relationship between the intensity of the bioluminescent signal and the level of ATP contained in the solution of the lysed bacterial cells. The highest sensitivity to ATP is achieved by using immobilized FLuc or reagents containing separately immobilized FLuc and D-luciferase. The limit of detection of ATP by the developed reagents is 0.3 pM, which corresponds to 20,000 cells·mL-1. The linear response range is between 0.3 pM and 3 nM ATP. The multicomponent reagent, containing co-immobilized FLuc and D-luciferin, shows insignificantly lower sensitivity to ATP-0.6 pM. Moreover, the proposed method of producing an immobilized firefly luciferin-luciferase system holds considerable promise for the development of bioluminescent biosensors intended for the analysis of microbial contamination.

Cooked sausage enriched with essential nutrients for the gastrointestinal diet

Introduction. People with gastrointestinal disorders should have a sparing diet with a balanced chemical and amino acid composition including all essential components. Based on formulations of meat products, we identified a number of essential nutritional components that could improve the diet for gastrointestinal pathologies. In this study, we aimed to develop a formulation for cooked sausage enriched with deficient essential nutrients. Study objects and methods. Our study object was cooked sausage. First, we analyzed the diet for people with gastrointestinal disorders. Then, we formulated a meat-based product (cooked sausage), determined its chemical and amino acid compositions, as well as vitamin and mineral contents, and assessed the balance of amino acids. Finally, we evaluated the biological value and safety of the formulated sausage on laboratory mice. Results and discussion. The chemical and amino acid compositions of a daily gastrointestinal diet in medical institutions revealed a deficiency of some water-soluble vitamins, vitamin A, calcium, magnesium, and iron, as well as an imbalance of amino acids. To replenish the deficiency, we formulated a meat-based product composed of trimmed beef and pork, beef liver, egg mix, food gelatin, chitosan succinate, rice flour, and soy fortifier. The product was classified as a meat and cereal cooked sausage of grade B, in which most amino acids were used for anabolic purposes. Its daily portion of 100 g eliminated the deficiency of potassium and iron, almost completely replenished magnesium, calcium, and vitamin A, as well as reduced the deficiency of dietary fiber by 4.8 g. The cytological studies of the blood of laboratory animals, whose basic diet contained the formulated sausage, proved its high biological value and safety. Conclusion. We found that the formulated meat and cereal sausage can be included in the diet for patients with gastrointestinal diseases and used in medical institutions to eliminate the deficiency of essential nutrients.

Thermal Inactivation of Butyrylcholinesterase in Starch and Gelatin Gels

The present study demonstrates a simple approach to enhancing thermal stability of butyrylcholinesterase (BChE) by using natural polymers. Analysis of thermal inactivation of the tetrameric BChE in starch and gelatin gels at 50–64 °C showed that thermal inactivation followed second-order kinetics and involved two alternating processes of BChE inactivation, which occurred at different rates (fast and slow processes). The activation enthalpy ΔH# and the activation entropy ΔS# for BChE in starch and gelatin gels were evaluated. The values of ΔH# for the fast and the slow thermal inactivation of BChE in starch gel were 61 ± 3, and 22 ± 2 kcal/mol, respectively, and the values of ΔS# were 136 ± 12 and −2.03 ± 0.05 cal∙K−1∙mol−1, respectively. Likewise, the values of ΔH# for BChE in gelatin gel were 58 ± 6 and 109 ± 11 kcal/mol, and the values of ΔS# were 149 ± 16 and 262 ± 21 cal∙K−1∙mol−1, respectively. The values of the activation parameters obtained in this study suggest that starch gel produced a stronger stabilizing effect on BChE exposed to elevated temperatures over long periods compared with gelatin gel.