Kinetics Of Hydrolysis Research Articles

Rhizobacteria-priming improves common bean seeds germination under different abiotic stresses through improving hydrolysis and antioxidant enzymes kinetics parameters

Bio-priming is a proven method for enhancing seed germination in stressful environments. Researchers have thoroughly explored its impact on enzyme activity during seed germination under diverse environmental stresses. Yet, there is limited knowledge about how bio-priming specifically influences enzyme kinetics. Understanding these kinetic changes could offer valuable insights into the metabolic adjustments and regulatory mechanisms employed by seeds to withstand stress. From this perspective, this study aims to investigate the effects of bio-priming with rhizobacteria on changes in hydrolysis enzymes (amylase and phytase) and antioxidant enzymes (superoxide dismutase and catalase) kinetics in germinated common bean seeds under different abiotic stresses. Two groups of common bean seeds germinated: the first consisted of dry seeds (non-primed), and the second was primed with Bacillus velezensis (bio-primed) under no-stress, drought, salinity, and lead acetate conditions. After 72 h of germination, the germination percentage was recorded. The germinated seeds underwent the extraction and purification of hydrolysis enzymes (amylase and phytase) and antioxidant enzymes (superoxide dismutase and catalase). The kinetic parameters (Michael constant, maximum velocity, turnover number, specificity constant, and catalytic efficiency) for each enzyme were determined. Bio-priming significantly improved common bean germination by enhancing the activity of hydrolysis enzymes and antioxidant enzymes. Enzyme kinetics changes significantly under stress, which indicates that there are differences in the enzyme configuration under stress that induce compounds that can inhibit enzyme activity by increasing the Km and decreasing the Vmax and the enzyme turnover Kcat. On the other hand, bio-priming significantly improved the catalytic efficiency of enzymes by decreasing the Km, increasing the Vmax, and increasing the enzyme turnover (Kcat) under both no-stress and stress conditions.

A Fractional‐Order Kinetics Approach for Modeling Enzymatic Starch Multiscale Digestion

AbstractThe characterization of the enzymatic hydrolysis of starch is a prerequisite for assessing the impact of starchy food in the gastrointestinal tract. The issue is relevant given the necessity of tailoring food products with a prescribed capacity of glucose production. Several empirical functions have been proposed for modeling starch digestograms. The first‐order exponential and the Weibull models are among the most used functions. Although tight numerical fitting of the experimental data may be obtained with such functions, a reliable interpretation of the underlying parameters is commonly a drawback. This work explores the use of fractional‐order kinetics for the modeling of starch digestograms. The aims are to show that: a) the fractional‐order framework offers a framework for capturing multiscale patterns observed, and b) the Weibull's and Peleg's models are particular cases of a more general function expressed as a generalized (Mittag‐Leffler) exponential function. The results showed that the Mittag–Leffler exponential function provided the best‐fitting results. However, the gain relative to Weibull's and fractional Peleg's functions may be small. It is concluded that Weibull's function approximates a more general function (the Mittag‐Leffler function), and as such its parameters find an easier interpretation in terms of the hydrolysis kinetics.

Enzymatic hydrolysis of whey proteins by the combination of Alcalase and Neutrase: Kinetic model and hydrolysis control

A combination of Alcalase and Neutrase was used to hydrolyse whey proteins and the hydrolysis kinetics mechanism was studied to achieve accurate control of the hydrolysis process. By measuring the degree of hydrolysis (DH) at different enzyme concentrations and different substrate concentrations, the hydrolysis kinetic model was established as: DH=6.536Ln[1+(4.687E0S0–0.0007)t]. The results showed that the theoretical and actual values of the model were in good agreement. Subsequently, the molecular mass distribution of the whey proteins hydrolysates at different DH was determined; it was found that the molecular mass components of 5–20 and >20 kDa gradually decreased with the increase of DH, while the percentage of <1 kDa gradually increased. Extensive hydrolysis of whey proteins was achieved when the DH reached 21–25%. The establishment of kinetic model has theoretical guidance for the accurate control of the whey proteins hydrolysis by the combination of Alcalase and Neutrase.

Electrocatalysis through interface and structural engineering of hollow/porous NiSe/CoSe2 nanotubes for overall water splitting

Nickel/cobalt-based selenides is considered as a promising electrocatalyst for overall water splitting ascribed to rapid electron transfer ability and long-term durability. However, the sluggish water dissociation kinetics and high Gibbs free energy seriously hinder its actual application. Herein, interface engineering is proposed to promote the formation of high-valence metal cations, thus activating the active center of electrocatalytic water dissociation and reducing the adsorption/desorption free energy of the intermediates significantly. In addition, a stable hollow mesoporous structure is constructed through structural engineering, which provides abundant accessible inner and outer surfaces, and the capillary phenomenon caused by the hollow structure promotes the adsorption of water molecules in the reaction center and the desorption of gases. Based on the coupling effect described above, the hollow/porous NiSe/CoSe2-100 nanotubes (denoted as NiSe/CoSe2-X HNTs, X is the weight of Se powder) demonstrate an overpotential of 117 and 225 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Meanwhile, the system of NiSe/CoSe2-100 HNTs//NiSe/CoSe2-100 HNTs requires a low voltage of 1.46 V to drive water splitting and the faraday efficiency is close to 100%. Overall, a new route is proposed for the construction of electrocatalysts with fast hydrolysis kinetics.

Catalysis in SDS and CTAB micellar media: Kinetics of base hydrolysis of Bis(2,4,6-tripyridyl-s-triazine) iron (II)

Kinetics of the hydrolysis of [Fe(tptz)2]2+ in the presence of NaOH has been studied in two different types of micellar media: SDS anionic and CTAB cationic. The reaction was found to be much faster in both the micellar media compared to aqueous medium (kSDS = 102.2 X10-4 mol-1dm3s-1, kCTAB = 43.92 X 10-4 mol-1dm3s-1, kaq = 0.115 X10-4 mol-1dm3s-1). The reaction obeys first order kinetics with respect to both the reactants in both the media. The rate constant versus surfactant profile shows a maximum in both cases which is characteristic of a bimolecular micelle catalyzed reaction. The kinetic behaviour has been accounted for by using the Berezin model.

Force-Triggered Self-Destructive Hydrogels.

Self-destructive polymers (SDPs) are defined as a class of smart polymers that autonomously degrade upon experiencing an external trigger, such as a chemical cue or optical excitation. Because SDPs release the materials trapped inside the network upon degradation, they have potential applications in drug delivery and analytical sensing. However, no known SDPs that respond to external mechanical forces have been reported, as it is fundamentally challenging to create mechano-sensitivity in general and especially so for force levels below those required for classical force-induced bond scission. To address this challenge, the development of force-triggered SDPs composed of DNA crosslinked hydrogels doped with nucleases is described here. Externally applied piconewton forces selectively expose enzymatic cleavage sites within the DNA crosslinks, resulting in rapid polymer self-degradation. The synthesis and the chemical and mechanical characterization of DNA crosslinked hydrogels, as well as the kinetics of force-triggered hydrolysis, are described. As a proof-of-concept, force-triggered and time-dependent rheological changes in the polymer as well as encapsulated nanoparticle release are demonstrated. Finally, that the kinetics of self-destruction are shown to be tuned as a function of nuclease concentration, incubation time, and thermodynamic stability of DNA crosslinkers.

Mechanism-based structure-activity relationship investigation on hydrolysis kinetics of atmospheric organic nitrates

Organic nitrates are key components of atmospheric organic aerosols. Hydrolysis is one of their main transformation pathways, affecting atmospheric nitrogen cycle and the properties of organic aerosols. Studying hydrolysis using experiments is hindered by limited authentic chemical standards. To advance our understanding on the hydrolysis of organic nitrates, we apply quantum chemistry methods here to establish a structure-activity relationship of the mechanisms and kinetics by selecting eight organic nitrates as model compounds. The results indicate that an acid-catalyzed mechanism is dominant for the most considered organic nitrates at pH corresponding to ambient organic aerosol (pH < 5). More importantly, a hydrolysis pathway driven by the shift of hydrogen or methyl cation is unveiled. Based on the revealed mechanisms, quaternary C at the α-site, tertiary/quaternary C at the β-site, and –C=C at the β/γ-site of the −ONO2 group are determined to be the key structural factors for the fast hydrolysis kinetics. An important feature for the hydrolysis of organic nitrates with such structural factors is proceeding via a carbocation intermediate. The formed carbocation could further mediate the organic aerosol chemistry, affecting the composition and properties of organic aerosols. This study provides a basis to further develop predictive models for hydrolysis kinetics of organic nitrates.

Assembly-driven protection from hydrolysis as key selective force during chemical evolution.

The origins of biopolymers pose fascinating questions in prebiotic chemistry. The marvelous assembly proficiencies of biopolymers suggest they are winners of a competitive evolutionary process. Sophisticated molecular assembly is ubiquitous in life where it is often emergent upon polymerization. We focus on the influence of molecular assembly on hydrolysis rates in aqueous media and suggest that assembly was crucial for biopolymer selection. In this model, incremental enrichment of some molecular species during chemical evolution was partially driven by the interplay of kinetics of synthesis and hydrolysis. We document a general attenuation of hydrolysis by assembly (i.e., recalcitrance) for all universal biopolymers and highlight the likely role of assembly in the survival of the 'fittest' molecules during chemical evolution.

Drug-Induced Conformational Dynamics of P-Glycoprotein Underlies the Transport of Camptothecin Analogs.

P-glycoprotein (Pgp) plays a pivotal role in drug bioavailability and multi-drug resistance development. Understanding the protein's activity and designing effective drugs require insight into the mechanisms underlying Pgp-mediated transport of xenobiotics. In this study, we investigated the drug-induced conformational changes in Pgp and adopted a conformationally-gated model to elucidate the Pgp-mediated transport of camptothecin analogs (CPTs). While Pgp displays a wide range of conformations, we simplified it into three model states: 'open-inward', 'open-outward', and 'intermediate'. Utilizing acrylamide quenching of Pgp fluorescence as a tool to examine the protein's tertiary structure, we observed that topotecan (TPT), SN-38, and irinotecan (IRT) induced distinct conformational shifts in the protein. TPT caused a substantial shift akin to AMPPNP, suggesting ATP-independent 'open-outward' conformation. IRT and SN-38 had relatively moderate effects on the conformation of Pgp. Experimental atomic force microscopy (AFM) imaging supports these findings. Further, the rate of ATPase hydrolysis was correlated with ligand-induced Pgp conformational changes. We hypothesize that the separation between the nucleotide-binding domains (NBDs) creates a conformational barrier for substrate transport. Substrates that reduce the conformational barrier, like TPT, are better transported. The affinity for ATP extracted from Pgp-mediated ATP hydrolysis kinetics curves for TPT was about 2-fold and 3-fold higher than SN-38 and IRT, respectively. On the contrary, the dissociation constants (KD) determined by fluorescence quenching for these drugs were not significantly different. Saturation transfer double difference (STDD) NMR of TPT and IRT with Pgp revealed that similar functional groups of the CPTs are accountable for Pgp-CPTs interactions. Efforts aimed at modifying these functional groups, guided by available structure-activity relationship data for CPTs and DNA-Topoisomerase-I complexes, could pave the way for the development of more potent next-generation CPTs.

Ultrasound-Assisted Enzymatic Protein Hydrolysis in Food Processing: Mechanism and Parameters.

Ultrasound has been widely used as a green and efficient non-thermal processing technique to assist with enzymatic hydrolysis. Compared with traditional enzymatic hydrolysis, ultrasonic-pretreatment-assisted enzymatic hydrolysis can significantly improve the efficiency of enzymatic hydrolysis and enhance the biological activity of substrates. At present, this technology is mainly used for the extraction of bioactive substances and the degradation of biological macromolecules. This review is focused on the mechanism of enzymatic hydrolysis assisted by ultrasonic pretreatment, including the effects of ultrasonic pretreatment on the enzyme structure, substrate structure, enzymatic hydrolysis kinetics, and thermodynamics and the effects of the ultrasonic conditions on the enzymatic hydrolysis results. The development status of ultrasonic devices and the application of ultrasonic-assisted enzymatic hydrolysis in the food industry are briefly described in this study. In the future, more attention should be paid to research on ultrasound-assisted enzymatic hydrolysis devices to promote the expansion of production and improve production efficiency.

Evaluation of the kinetics of low intensity ultrasound-assisted sulfuric acid hydrolysis to obtain cellulose nanocrystals (CNCs) from microcrystalline cellulose (MCC)

Evaluation of the kinetics of low intensity ultrasound-assisted sulfuric acid hydrolysis to obtain cellulose nanocrystals (CNCs) from microcrystalline cellulose (MCC)

Effects of solution concentration and water amount on hydrogenation performance of MgH2

Hydride hydrolysis reaction is a promising method for on-site hydrogen production with high capacity. However, ensuring a certain amount of water and the formation of a passivation layer in the produced material is crucial to interrupt the reaction. In this experimental study, multiple hydrolysis experiments using chloride solutions at concentrations of 0.1 M, 0.5 M, and 1 M were investigated. Hydrolysis kinetics curves were measured at different temperatures. The resulting hydrolyzed products underwent analysis of phase and morphology using XRD and SEM scanning techniques, and the hydrolysis mechanism was examined. The results demonstrated that the hydrolysis activation energy for the 0.1 M, 0.5 M, and 1 M MgCl2 solutions was determined to be 42.62 ± 7, 37.4 ± 0.6, and 27.1 ± 0.5 kJ/mol, respectively, establishing the impact of concentration on the hydrolysis kinetics. Moreover, water reduction tests conducted under the original conditions revealed that using 0.1 M FeCl3 and 0.1 M AlCl3 solutions with 5 mL water yielded a hydrolysis yield of 1500 mL/g, and the conversion rate can reach 97 % in 2 mL of water in 0.5 M FeCl3 solution. These remarkable hydrolysis properties of MgH2 are significant for the study of related magnesium-based alloy hydrides.

Structure-guided discovery of aminopeptidase ERAP1 variants capable of processing antigens with novel PC anchor specificities.

Endoplasmic reticulum aminopeptidase 1 (ERAP1) belongs to the oxytocinase subfamily of M1 aminopeptidases (M1APs), which are a diverse family of metalloenzymes involved in a wide range of functions and have been implicated in various chronic and infectious diseases of humans. ERAP1 trims antigenic precursors into correct sizes (8-10 residues long) for Major Histocompatibility Complex (MHC) presentation, by a unique molecular ruler mechanism in which it makes concurrent bindings to substrate N- and C-termini. We have previously determined four crystal structures of ERAP1 C-terminal regulatory domain (termed ERAP1_C domain) in complex with peptide carboxyl (PC)-ends that carry various anchor residues, and identified a specificity subsite for recognizing the PC anchor side chain, denoted as the SC subsite to follow the conventional notations: S1 site for P1, S2 site for P2, and so forth. In this study, we report studies on structure-guided mutational and hydrolysis kinetics, and peptide trimming assays to further examine the functional roles of this SC subsite. Most strikingly, a point mutation V737R results in a change of substrate preference from a hydrophobic to a negatively charged PC anchor residue; the latter is presumed to be a poor substrate for WT ERAP1. These studies validate the crystallographic observations that this SC subsite is directly involved in binding and recognition of the substrate PC anchor and presents a potential target to modulate MHC-restricted immunopeptidomes.

Hydrolysis Optimization of By-Products from the Potato Processing Industry and Biomethane Production from Starch Hydrolysates

This study aims to investigate the use of Fenton reagents for the efficient hydrolysis of starch, an industrial by-product obtained from the potato processing industry. A full factorial design experiment (FFD) was conducted and a statistical model was developed for simulating the hydrolysis process. The most important factors were the hydrolysis temperature and the amount of H2O2 followed by the interaction of FeSO4·7H2O and temperature. At maximum levels of FeSO4·7H2O (1.00g/L), H2O2 (0.51 g/L), and temperature (70.0 °C), a 99.5% hydrolysis yield was achieved, with a carbohydrate content of 28.65 g/L. Furthermore, analysis of hydrolysis kinetics demonstrated that an increased concentration of FeSO4·7H2O results in a decelerated rate of starch hydrolysis. Moreover, biodegradability tests were carried out to estimate the methane production potential from the produced hydrolysates. The specific methanogenic activity (SMA) was reached at 0.669 ± 0.014 g CH4-COD g−1 VSS day−1 proving the effectiveness of the hydrolysis process and highlighting the potential of industrial starch for bioenergy production. A preliminary cost analysis showed that a small investment for utilizing the starch in an existing wastewater treatment facility of a potato processing company becomes profitable before the end of the 3rd year, obtaining a net present value (NPV) 37.5% higher than that of the current utilization scenario.

Preparation, structure, and in-vitro hypoglycemic potential of debranched millet starch-fatty acid composite resistant starch

Currently, the preparation methods and basic physicochemical properties of starch-FA complexes have been widely studied; however, no in-depth research on the regulatory mechanism of the digestive properties of debranched starch-unsaturated FA complexes has been conducted. Therefore, six fatty acids with different carbon chains and different degrees of unsaturation were complexed with de-branched millet starch in this research, using the microwave method. Microwave millet starch-linoleic acid complex (MPS-LOA) had the highest resistant starch (RS) content, and the structure and physicochemical properties of MPS-LOA were determined using various molecular techniques. The results indicate that MPS-LOA had a resistant starch (RS) content of 40.35% and the most notable fluorescence. The characteristic UV peaks of MPS-LOA were blue-shifted, and new IR peaks appeared. The crystalline structure changed to V-type crystals, the crystallinity increased, and the molecular weight decreased. The enthalpy and coagulability of MPS-LOA increased, and the swelling force decreased. Additionally, MPS-LOA showed enhanced α-glucosidase and α-amylase inhibition, and in-vitro hydrolysis kinetics analysis of MPS-LOA showed a hydrolysis index of 53.8 and an extended glycemic index (eGI)I of 54.6, indicating a low eGI food suitable for consumption by people with type II diabetes. These results provide a theoretical basis for the preparation of amylopectin- and starch-based foods with an anti-enzyme structure and a low glycemic index (GI).

Deterioration of basalt-based reinforcement in corrosive environments: experimental monitoring and mathematical models

The basalt-based reinforcing elements are considered as alternative to conventional steel-based reinforcing elements (rebars, wires). The motivation to use basalt-based elements (fibers, composite bars, meshes etc.) is better corrosion resistance of basalt fibers especially in sea-water environment, compared to carbon steel. Nevertheless, it does not mean that basalt fibers are 100% corrosion resistant. The basalt fibers are produced from silicate melt of proper composition, i.e. the basalt fibers are vulnerable to both acid and alkaline hydrolysis, as well as other silicates do. When basalt fibers are used as reinforcement in concrete, the alkaline hydrolysis will become an important issue. The present paper deals with experimental observation of basalt fibers in alkaline environment of Simulated Pore Solution. The fibers deterioration was monitored by their mass loss and SEM microscopy. Jander’s model was used to describe mathematically the kinetics of the fibers alkaline hydrolysis. The results revealed that a corrosion products layer is formed on the fibers surface in this environment. The composition of this layer corresponds to N-A-S-H and C-A-S-H phases known from alkali-activated aluminosilicates or hydrated Portland cement.

Hydrolysis hydrogen generation behavior of Mg10Ni10Ce alloy catalytic modified by isomeric carbon materials

Hydrolysis hydrogen generation from Mg-based alloys is considered as a potential energy carrier for global low-carbon and growing energy challenges. At present, it is a key problem to explore an efficient modification method for Mg-based alloys to obtain rapid initial hydrolysis kinetics and high H2 yield in short time. In this work, carbon-based isomeric catalysts were creatively employed to activate Mg10Ni10Ce alloy. Based on the rapid initial hydrolysis kinetics, the effects of carbon nanostructured catalysts on the hydrogen production of Mg10Ni10Ce were studied. Herein, the catalytically modified Mg10Ni10Ce samples with point-like carbon black (SP), one-dimensional tubular carbon nanotubes (CNTs) and two-dimensional layered graphite (GP) are simply prepared by short-time high-energy ball milling process. Due to the significant structural characteristics, the catalytically modified Mg10Ni10Ce samples have higher H2 yields at the initial hydrolysis stage, Mg10Ni10Ce-SP, Mg10Ni10Ce-CNTs and Mg10Ni10Ce-GP samples are 17.3%, 25.2% and 36.2% at 313 K for 30 s, which are higher than that of Mg10Ni10Ce (10.4%). The above work provides an effective strategy for hydrogen production by modifying Mg-based alloys with nanostructured catalysts, and lays a foundation for the application of portable hydrogen production devices.

Local high concentration alkali field accelerated silicon hydrolysis for hydrogen production

Silicon is considered as a promising portable hydrolytic hydrogen production material due to its abundant raw materials, high theoretical capacity (1600 mL/g) and facile storage. However, the low hydrolysis activity and slow hydrolysis rate of silicon hinder its practical application. To address this issue, we introduced CaH2 to form Si-based composites via a flexible ball milling method. The above composites showed ideal yield (1216 mL/g in 10 min), reaction conversion (95.5%) and fast hydrolysis kinetics (225 mL/(s·g)) in deionized water, which is one of the best hydrolysis performances of Si-based composites so far. The hydrolytic process can be divided into two steps: the splitting hydrolysis of CaH2 and the continuous hydrolysis of Si. Combining the dynamic in-situ structural analysis with the analogue simulation, it can be confirmed that the formation of local high concentration alkali field is the key to promote the complete hydrolysis and achieve high yield and fast kinetics of the composites. The existence of lattice defects was proved and the adsorption of Si to hydroxide ion was proved by theoretical calculation. Our work provided a novel idea for the theoretical design of hydrolytic hydrogen production compounds and promoted the practical application of low cost and portable hydrolytic hydrogen production materials.

Hydrolytic degradation of poly(lactic acid): Unraveling correlations between temperature and the three phase structures

Hydrolysis significantly influences both the properties and degradability of poly(lactic acid), PLA. This work investigates the hydrolysis kinetics of PLA films as affected by degree of crystallinity and temperatures by considering the three-phase model structures (i.e., mobile amorphous, rigid amorphous, and crystalline). Molecular weight and three-phase fraction analyses were performed during hydrolysis to estimate the kinetic rates using phenomenological models. Results revealed that temperature significantly impacted PLA degradation, with distinct characteristics observed for each of these three phases. Above the glass transition temperature, the hydrolysis rates of PLA were comparable among samples with different crystallinity due to rapid water-induced crystallization of the amorphous phases, coupled with accelerated hydrolysis. In contrast, at below the glass transition temperature, the higher crystallinity sample exhibited a faster hydrolysis rate attributed to the presence of the rigid amorphous fraction. An increase in crystallinity introduced more defects due to limited mobility in the rigid amorphous fraction, influencing hydrolysis. The study provides valuable insights into the crucial relationship between temperature, crystallinity, and hydrolysis kinetics which are expected to be useful for predicting PLA degradation behavior during its intended applications and at its end of life.

Hydrolysis of propyrisulfuron in water: Kinetics, influence of 34 environmental factors, transformation products identification, mechanisms and toxicities

Propyrisulfuron is a novel sulfonylurea herbicide used for controlling annual grass and broad-leaved weeds in fields, but its fates and behaviors in environment are still unknown, which are of utmost importance for environmental protection. To reduce its potential environmental risks in agricultural production, the hydrolysis kinetics, influence of 34 environmental factors including 12 microplastics (MPs), disposable face masks (DFMs) and its different parts, 6 fertilizers, 5 ions, 3 surfactants, a co-existed herbicide of florpyrauxifen-benzy, humic acid and biochar, and the effect of MPs and DFMs on its hydrolysis mechanisms were systematically investigated. The main hydrolysis products (HPs), possible mechanisms, toxicities and potential risks to aquatic organisms were studied. Propyrisulfuron hydrolysis was an acid catalytic pyrolysis, endothermic and spontaneous process driven by the reduction of activation enthalpy, and followed the first-order kinetics. All environmental factors can accelerate propyrisulfuron hydrolysis to varying degrees except humic acid, and different hydrolysis mechanisms occurred in the presence of MPs and DFMs. In addition, 10 possible HPs and 7 possible mechanisms were identified and proposed. ECOSAR prediction and ecotoxicity testing showed that acute toxicity of propyrisulfuron and its HPs for aquatic organisms were low, but may have high chronic toxicity and pose a potential threat to aquatic ecosystems. The investigations are significantly important for elucidating the environmental fates and behaviors of propyrisulfuron, assessing the risks in environmental protection, and further providing guidance for scientific application in agro-ecosystem.