Mechanism Of Enzymatic Hydrolysis Research Articles

Novel glycosidase from Paenibacillus lactis 154 hydrolyzing the 28-O-β-d-glucopyranosyl ester bond of oleanane-type saponins

Oleanane-type ginsenosides are a class of compounds with remarkable pharmacological activities. However, the lack of effective preparation methods for specific rare ginsenosides has hindered the exploration of their pharmacological properties. In this study, a novel glycoside hydrolase PlGH3 was cloned from Paenibacillus lactis 154 and heterologous expressed in Escherichia coli. Sequence analysis revealed that PlGH3 consists of 749 amino acids with a molecular weight of 89.5 kDa, exhibiting the characteristic features of the glycoside hydrolase 3 family. The enzymatic characterization results of PlGH3 showed that the optimal reaction pH and temperature was 8 and 50 °C by using p-nitrophenyl-β-d-glucopyranoside as a substrate, respectively. The Km and kcat values towards ginsenoside Ro were 79.59 ± 3.42 µM and 18.52 s−1, respectively. PlGH3 exhibits a highly specific activity on hydrolyzing the 28-O-β-d-glucopyranosyl ester bond of oleanane-type saponins. The mechanism of hydrolysis specificity was then presumably elucidated through molecular docking. Eventually, four kinds of rare oleanane-type ginsenosides (calenduloside E, pseudoginsenoside RP1, zingibroside R1, and tarasaponin VI) were successfully prepared by biotransforming total saponins extracted from Panax japonicus. This study contributes to understanding the mechanism of enzymatic hydrolysis of the GH3 family and provides a practical route for the preparation of rare oleanane-type ginsenosides through biotransformation.Key points• The glucose at C-28 in oleanane-type saponins can be directionally hydrolyzed.• Mechanisms to interpret PlGH3 substrate specificity by molecular docking.• Case of preparation of low-sugar alternative saponins by directed hydrolysis.

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.

Effect of the Temperature and Molar Ratio of Water-Oil on the Enzymatic Hydrolysis Kinetics of the Soybean Oil: Experimental and Mathematical Modeling

The objective of this paper was to evaluate the kinetics of the hydrolysis of soybean oil by the action of the Lipozyme® TL IM enzyme varying the operational conditions of molar ratio water/oil (9:1-60:1) and temperature (40-64 °C). To describe the experimental data, a mathematical model based on the kinetic mechanism of Ping-Pong Bi Bi (PPBB) was proposed, in which the following steps were not considered formation of the complex enzyme/oil substrate, and formation of the acylated enzyme/oil substrate complex. The results of enzymatic hydrolysis of soybean oil indicated a yield in free fatty acids of 76% at the molar ratio of 46:1 and temperature of 52 °C. Furthermore, based on the values of the determination coefficient and root mean square error, the mathematical model based on the kinetic mechanism of PPBB showed good agreement with the experimental data in a relatively wide temperature range. Thus, it can be a useful tool for the optimization and assessment of the mechanisms of enzymatic hydrolysis of vegetable oil.

Characterization of proteases from Irpex lacteus grown on minimally denatured soybean meal.

Acid and thermal stabilities are important properties for the preparation of acidic protein beverage. It is an important method for enzymatic modification to improve the functional properties of protein. Irpex lacteus protease showed a selective hydrolysis to soy proteins. The purpose of this study was to investigate the mechanism of enzymatic hydrolysis and its effects on acid and thermal stabilities of soy proteins. The I.lacteus protease selectively hydrolyzed the α and α' subunits of the native soybean β-conglycinin (7S globulin) to produce products that presented as the 55 kDa band upon sodium dodecyl sulfate polyacrylamide gel electrophoresis. The amino acid sequences of 55 kDa polypeptides were analyzed in gel multi-enzyme digestion followed by liquid chromatography-mass spectrometry. By matching the multi-enzyme digestion peptides with the published polypeptide chain sequences of the α and α' subunits, it was confirmed that the 55 kDa polypeptides were formed by eliminating amino acid residues on both sides of the N- and C-terminals. From the published protein structure database (https://www.uniprot.org/), it is known that the cleaved peptide bonds were in extension regions. Non-selective enzyme hydrolysis of both β-conglycinin (7S globulin) and glycinin (11S globulin), with corresponding drastic increases in the degree of hydrolysis, was observed when the substrates were preheated to the denaturation degree of 40% and above. However, 55 kDa hydrolyzed products and B polypeptides showed some extent of resistance to the proteolysis by I.lacteus protease even if denaturation degree was 100%. Both selective and non-selective hydrolysis of soy proteins by I.lacteus protease improved the acid and heat stabilities under the same hydrolysis conditions (enzyme/substrate ratio, time, and temperature). Enzymatic hydrolysis of soybean proteins by the I.lacteus protease can effectively improve the acid and thermal stabilities of proteins. This discovery is significant to avoid aggregation during processing in the beverage industry. In the near future, the protease has potential application value for modification of other proteins. © 2022 Society of Chemical Industry.

Immunomodulatory effects of polysaccharides enzymatic hydrolysis from Hericium erinaceus on the MODE-K/DCs co-culture model

The aim of this study was to explore the indirect immunomodulatory activities and its mechanism of enzymatic hydrolysis of Hericium erinaceus polysaccharides (EHEP) in the MODE-K/DCs co-culture model. According to the TEER value, transmission of phenol red and AKP activity of MODE-K cells, single model was established in order to evaluate the eligibility of MODE-K cells monolayer. Then the MODE-K/DCs co-culture model was set up and HEP and EHEP were added into the apical chamber, DCs were obtained for the expression of key surface markers, the ability of phagocytosis, the morphology, the secretion of cytokines and the production of target proteins. We found that after 21 d of culture, the MODE-K cells monolayer became intact and dense, which can be used for the MODE-K/DCs co-culture model. Under the treatment of HEP and EHEP, immature DCs become into mature DCs with the high expression of CD86 and MHCII, the low antigens up-taking, the typical morphology, the more content of IL-12 and TNF-α and the high level of TLR4, MyD88 and NF-κB proteins. However, compared with HEP, EHEP showed the better immunomodulatory activities. These findings indicated that EHEP could indirectly affect the immune function of DCs in the MODE-K/DCs co-culture model.

Kinetics of Enzymatic Hydrolysis of Passion Fruit Peel using Cellulase in Bio-ethanol Production

This research aims to study the hydrolysis of passion fruit peel using cellulase and its evaluation for ethanol production. Passion fruit peel is a fruit processing waste that has not been utilized properly. Passion fruit peel contains holo-cellulose (64% w/w), which can be converted into ethanol through hydrolysis followed by fermentation. Hydrolysis using cellulase is more efficient and its fermentation using yeast to produce ethanol is common. The hydrolysis is carried out at various enzyme ratios (3, 5, 7, and 9% v/v) and at temperature 30 oC, material concentration 5 g/100 mL, pH 4-5, and shaking speed 160 rpm. The kinetics chosen were heterogeneous models; they were the fractal model by Valjamae and Kopelman. Before being hydrolyzed, the essential oil and pectin in passion fruit peel were extracted, because the compositions were quite high; the results were around 16.23 and 11.36% w/w, respectively. The effect of the enzyme ratio to the sugar concentration by hydrolysis is very significant. At 9 h, the glucose concentration reached 45.38, 51.86, 60.50, 66.00 g/L at various enzyme ratios of 3, 5, 7, 9% v/v. During the hydrolysis, the glucose concentration continues to increase and starts to decrease after 9 h. Hydrolyzate solution fermentation obtained from hydrolysis in various enzyme ratios showed consistent results; the higher the enzyme ratio and glucose, and the higher the ethanol will be (5.6, 6.8, 7.6, and 8.9% v/v). The kinetics model by Valjamae is more appropriate to describe the enzymatic hydrolysis mechanism of passion fruit peel than Kopelman. The fractal exponent values obtained from Valjamae and Kopelman models were 0.28 and 0.27. In Valjamae model, the enzyme ratio rises, from 3 to 9% v/v, the rate constant rises from 0.22 to 0.53 1/h. In Kopelman model, the rate constant rises too, from 0.21 to 0.51 1/h.Keywords: bio-ethanol; cellulase; enzymatic hydrolysis; fractal kinetic; passion fruit peel

Exploring surface properties of substrate to understand the difference in enzymatic hydrolysis of sugarcane bagasse treated with dilute acid and sulfite

The sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) is beneficial to subsequent enzymatic hydrolysis. In this study, to elucidate enzymatic hydrolysis mechanism of SPORL treated sugarcane bagasse (SCB), the surface properties of SPORL and dilute acid (DA) treated SCBs were compared, including cellulase adsorption isotherm and kinetics, specific surface area and average size of pores, water retention value (WRV), element composition and percentages of different chemical bonds on the substrate surface. The results showed the hydrolysis yield of SPORL SCB (76.16 %) was higher than that of DA (57.82 %) and SPORL SCB had better adsorption capacity, lower binding strength, a higher cellulase adsorption rate, larger specific surface area and higher WRV, and these two SCBs might adsorb cellulase by COR bonds (R: organic groups), suggesting SPORL SCB’s surface was more advantageous to enzymatic hydrolysis. This study could help understand the mechanism of lignocellulosic hydrolysis in depth.

The separation and identification of the residual antigenic fragments in soy protein hydrolysates.

Soybean is one of the major food allergens. In this study, soy protein isolate was hydrolyzed by Neutrase and Flavourzyme. The hydrolysates were separated by ultrafiltration and ion-exchange chromatography. The antigenicity of proteins was determined by indirect competitive ELISA. The molecular weight distribution was characterized by SDS-PAGE. The amino acid sequence of chromatography fractions was analyzed by LC-MS. The results showed that proteins with >50kDa in hydrolysates had the highest antigenicity and were further separated into F1 -F5 fragments by ion-exchange chromatography. Fragment F4 , which was the most antigenic, was analyzed by LC-MS. The results of mass spectrometry showed that most of the peptides that contained antigen epitopes in chromatography fraction F4 belonged to glycinin subunits. The antigenicity of soy protein was reduced by enzymatic hydrolysis, but glycinin showed resistance to enzymatic hydrolysis. PRACTICAL APPLICATIONS: The identification of residual antigenicity in soy protein hydrolysates by LC-MS provides important information on the resistance mechanism of enzymatic hydrolysis of soybean protein allergens. In addition, the efficient separation of soy protein hydrolysates could be beneficial for developing low-allergenic soybean products.

Study on the Kinetics of Salmon Skin Proteolysis

In this study, in order to study the kinetic mechanism of enzymatic hydrolysis of salmon protein, the kinetic model of enzymatic hydrolysis of salmon skin protein by papain was established. The skin protein of salmon was hydrolyzed by papain under the following conditions: the mass concentration of salmon skin protein is 55 g/L, the initial papain concentration is 2.0 g/L, the pH of enzymatic solution is 7.2 and the temperature of enzymatic hydrolysis is 55 °C. Finally, the kinetic model of hydrolysis was established as follows: Hydrolysis rate R =(27.217E0–0 0357S0exp[–0.2587(DH)]; Degree of hydrolysis DH = 3.879 ln[1 + 7.0165E0/S0 –0.0092t]. The reaction rate constant k3 = 27.217 min–1 and the enzyme deactivation constant kd = 7.0752 min–1 were deduced to control the enzymatic hydrolysis process. Further verification tests showed that the theoretical value of the degree of hydrolysis of the model was basically consistent with the actual value, and the kinetic model had certain practical value, indicating that the established salmon skin protease kinetic model could be used to guide and optimize the enzymatic hydrolysis process.

Insight into the transformation of 4’-O-methylpyridoxine and 4’-O-methylpyridoxine-5’-glucoside in Ginkgo biloba seeds undergoing the heat treatment

Overconsumption of Ginkgo biloba seeds leads to poisoning. 4’-O-methylpyridoxine (MPN) and 4’-O-methylpyridoxine-5’-glucoside (MPNG) are responsible for poisoning by intaking ginkgo seeds. It had been reported that heat treatment could increase the MPNG content but decrease the MPN content in ginkgo seeds. However, the definite mechanism for the transformation of MPN and MPNG in ginkgo seeds undergoing heat treatment has not been elucidated to this day. In this work, a Chinese ginkgo cultivar was firstly employed to investigate the effect of heat treatment on the levels of MPN and MPNG. Similar syngenetic succession between the MPN and MPNG contents was also found. Several groups of experiments were further designed to explore the interconversion mechanism between MPN and MPNG under heat treatment. The results showed that non-enzymatic and enzymatic glycosylation mechanisms could not explain the transformation between MPN and MPNG. Enzymatic hydrolysis mechanism could better explain the dynamic relationship between the MPN and MPNG. Therefore, inactivating the endogenous enzymatic hydrolysis before HPLC analysis is needed to accurately determine the contents of MPN and MPNG in the ginkgo seeds.

Dual substrate/solvent- roles of water and mixed reaction-diffusion control of β-Galactosidase catalyzed reactions in PEG-induced macromolecular crowding conditions

Here we studied the effect of molecular crowding on the hydrolysis of ortho- and para-nitrophenyl-β-D-galactopyranosides (ONPG, PNPG) catalysed by Escherichia coli β-Galactosidase in the presence of 0–35%w/v 6kD polyethyleneglycol (PEG6000). The Eadie-Hofstee data analysis exhibited single straight lines for PNPG at all [PEG6000] as well as for ONPG in the absence of PEG6000 so a Michaelian model was applied to calculate the kinetic parameters KM and kcat (catalytic rate constant) values. However, for ONPG hydrolysis in the presence of PEG6000, the two slopes visualized in Eadie-Hofstee plots leaded to apply a biphasic kinetic model to fit initial rate vs. [ONPG] plots hence calculating two apparent KM and two kcat values. Since the rate limiting-step of the enzymatic hydrolysis mechanism of ONPG, but not of PNPG, is the water-dependent one, the existence of several molecular water populations differing in their energy and/or their availability as reactants may explain the biphasic kinetics in the presence of PEG6000. With PNPG, KM as well as kcat varied with [PEG6000] like a parabola opening upward with a minimum at 15 %w/v [PEG6000]. In the case of ONPG, one of the components became constant while the other component exhibited a slight increasing tendency in kcat plus high and [PEG6000]-dependent increasing KM values. Sedimentation velocity analysis demonstrated that PEG6000 impaired the diffusion of β-Gal but not that of substrates. In conjunction, kinetic data reflected complex combinations of PEG6000-induced effects on enzyme structure, water structure, thermodynamic activities of all the chemical species participating in the reaction and protein diffusion.

Correlation between the chemical structure and enzymatic hydrolysis of Poly(butylene succinate), Poly(butylene adipate), and Poly(butylene suberate)

Poly(butylene succinate) (PBS), poly(butylene adipate) (PBA), and poly(butylene suberate) (PBSub) were synthesized and enzymatic hydrolysis was performed in the presence of cutinase. The residues degraded at different times were characterized with respect to their molecular, thermal, crystalline, and chemical structures. The results showed that the degradation behavior of the three polyesters highly depends on their CH2/CO ratio, morphology, and thermal characteristics. The three polyesters were nearly degraded after 24 h, and the degradation rates was in the order of PBSub > PBA > PBS. Gel permeation chromatography and end-group analysis confirmed that the mechanism of enzymatic hydrolysis changed from endo-type to exo-type. The analyses of differential scanning calorimetry, powder X-ray diffraction, and Fourier transform infrared spectroscopy indicated that the cutinase could simultaneously degrade the crystalline and amorphous regions of polyester films.

Production of Bioethanol from Fruit Wastes (Banana, Papaya, Pineapple and Mango Peels) Under Milder Conditions

A very huge amounts of fruit wastes are available as sugar laden wastes world over. In fact, there is a need to recover value added products from these wastes. Fruit wastes are rich in sugars and carbohydrates which can be recovered and utilized for the production of bioethanol. Gasoline is being used at very huge scales globally. Therefore, plenty of bioethanol would be required to be produced if bioethanol has to replace gasoline as a fuel. Present studies are directed towards finding cost effective ways to recover sugars from fruit wastes starting initially without using any acidic or enzyme catalysts. In the present studies fruit wastes, such as, peels of banana (BP), pineapple (PAP), papaya (PP) and mango (MP) were used. The studies were aimed to find out the potential of these fruit wastes to produce total reducing sugars (TRS), pentose sugars (PS) and bioethanol. Simple soaking in water and steaming resulted in the recovery of free sugars. Enzymatic hydrolysis using cellulase and xylanase enzymes was found to show good yields of total reducing sugars and pentose sugars. BP and PAP were found to be the potential candidates for the production of bioethanol. In comparison to the enzymatic hydrolysis, the acidic hydrolysis using dilute H2SO4 was found to give higher yields of TRS and PS from fruit wastes in shorter times. However, the enzymatic hydrolysis was found to be a better choice for the production of bioethanol from the BP and PAP hydrolysates in order to avoid the inhibitory effect of yeast toxicants produced. Since the pretreatments by using costly chemicals are the costly steps in the enzymatic hydrolysis of biomass the presently developed pretreatment step seems to be a cost-effective method of pretreatment for the enzymatic hydrolysis. Therefore, simple water soaking, and steaming was found to be an inexpensive way to recover free sugars from fruit wastes. Enzymatic hydrolysis followed by the fermentation of hydrlysate using Saccharomyces cerevisae was found to produce bioethanol from the water-steam pretreated fruit wastes. Possible mechanism of enzymatic hydrolysis has also been suggested. Effect of enzyme concentration on the hydrolysis of PAP and BP for different times at 50°C was studied. Present studies showed that fruit wastes could be exploited as a potential source of bioethanol through simple water-steam soaking followed by the hydrolysis and fermentation processes.

Effect of high hydrostatic pressure on the enzymatic hydrolysis of bovine serum albumin.

The extent of enzymatic proteolysis mainly depends on accessibility of the peptide bonds, which stabilize the protein structure. The high hydrostatic pressure (HHP) process is able to induce, at certain operating conditions, protein displacement, thus suggesting that this technology can be used to modify protein resistance to the enzymatic attack. This work aims at investigating the mechanism of enzymatic hydrolysis assisted by HHP performed under different processing conditions (pressure level, treatment time). Bovine serum albumin was selected for the experiments, solubilized in sodium phosphate buffer (25 mg mL-1 , pH 7.5) with α-chymotrypsin or trypsin (E/S ratio = 1/10) and HPP treatment (100-500 MPa, 15-25 min). HHP treatment enhanced the extent of the hydrolysis reaction of globular proteins, being more effective than conventional hydrolysis. At HHP treatment conditions maximizing the protein unfolding, the hydrolysis degree of proteins was increased as a consequence of the increased exposure of peptide bonds to the attack of proteolytic enzymes. The maximum hydrolysis degree (10% and 7% respectively for the samples hydrolyzed with α-chymotrypsin and trypsin) was observed for the samples processed at 400 MPa for 25 min. At pressure levels higher than 400 MPa the formation of aggregates was likely to occur; thus the degree of hydrolysis decreased. Protein unfolding represents the key factor controlling the efficiency of HHP-assisted hydrolysis treatments. The peptide produced under high pressure showed lower dimensions and a different structure with respect to those of the hydrolysates obtained when the hydrolysis was carried out at atmospheric pressure, thus opening new frontiers of application in food science and nutrition. © 2016 Society of Chemical Industry.

Physicochemical Structural Changes of Cellulosic Substrates during Enzymatic Saccharification

Enzymatic hydrolysis represents one of the major steps and barriers in the commercialization process of converting cellulosic substrates into biofuels and other value added products. It is usually achieved by a synergistic action of enzyme mixture typically consisting of multiple enzymes such as glucanase, cellobiohydrolase and β-glucosidase with different mode of actions. Due to the innate biomass recalcitrance, enzymatic hydrolysis normally starts with an initial fast rate of hydrolysis followed by a rapid decrease of rate toward the end of hydrolysis. With majority of literature studies focusing on the effect of key substrate characteristics on the initial rate or final yield of enzymatic hydrolysis, information about physicochemical structural changes of cellulosic substrates during enzymatic hydrolysis is still quite limited. Consequently, what slows down the reaction rate toward the end of hydrolysis is not well understood. This review highlights recent advances in understanding the structural changes of cellulosic substrates during the hydrolysis process, to better understand the fundamental mechanisms of enzymatic hydrolysis.

Insights into the mechanism of enzymatic hydrolysis of xylan.

Hemicelluloses are a vast group of complex, non-cellulosic heteropolysaccharides that are classified according to the principal monosaccharides present in its structure. Xylan is the most abundant hemicellulose found in lignocellulosic biomass. In the current trend of a more effective utilization of lignocellulosic biomass and developments of environmentally friendly industrial processes, increasing research activities have been directed to a practical application of the xylan component of plants and plant residues as biopolymer resources. A variety of enzymes, including main- and side-chain acting enzymes, are responsible for xylan breakdown. Xylanase is a main-chain enzyme that randomly cleaves the β-1,4 linkages between the xylopyranosyl residues in xylan backbone. This enzyme presents varying folds, mechanisms of action, substrate specificities, hydrolytic activities, and physicochemical characteristics. This review pays particular attention to different aspects of the mechanisms of action of xylan-degrading enzymes and their contribution to improve the production of bioproducts from plant biomass. Furthermore, the influence of phenolic compounds on xylanase activity is also discussed.

Cerium oxide for the destruction of chemical warfare agents: A comparison of synthetic routes

Four different synthetic routes were used to prepare active forms of cerium oxide that are capable of destroying toxic organophosphates: a sol–gel process (via a citrate precursor), homogeneous hydrolysis and a precipitation/calcination procedure (via carbonate and oxalate precursors). The samples prepared via homogeneous hydrolysis with urea and the samples prepared via precipitation with ammonium bicarbonate (with subsequent calcination at 500°C in both cases) exhibited the highest degradation efficiencies towards the extremely dangerous nerve agents soman (O-pinacolyl methylphosphonofluoridate) and VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate) and the organophosphate pesticide parathion methyl. These samples were able to destroy more than 90% of the toxic compounds in less than 10min. The high degradation efficiency of cerium oxide is related to its complex surface chemistry (presence of surface OH groups and surface non-stoichiometry) and to its nanocrystalline nature, which promotes the formation of crystal defects on which the decomposition of organophosphates proceeds through a nucleophilic substitution mechanism that is not dissimilar to the mechanism of enzymatic hydrolysis of organic phosphates by phosphotriesterase.

Impact of the supramolecular structure of cellulose on the efficiency of enzymatic hydrolysis.

BackgroundThe efficiency of enzymatic hydrolysis is reduced by the structural properties of cellulose. Although efforts have been made to explain the mechanism of enzymatic hydrolysis of cellulose by considering the interaction of cellulolytic enzymes with cellulose or the changes in the structure of cellulose during enzymatic hydrolysis, the process of cellulose hydrolysis is not yet fully understood. We have analysed the characteristics of the complex supramolecular structure of cellulose on the nanometre scale in terms of the spatial distribution of fibrils and fibril aggregates, the accessible surface area and the crystallinity during enzymatic hydrolysis. Influence of the porosity of the substrates and the hydrolysability was also investigated. All cellulosic substrates used in this study contained more than 96% cellulose.ResultsConversion yields of six cellulosic substrates were as follows, in descending order: nano-crystalline cellulose produced from never-dried soda pulp (NCC-OPHS-ND) > never-dried soda pulp (OPHS-ND) > dried soda pulp (OPHS-D) > Avicel > cotton treated with sodium hydroxide (cotton + NaOH) > cotton.ConclusionsNo significant correlations were observed between the yield of conversion and supramolecular characteristics, such as specific surface area (SSA) and lateral fibril dimensions (LFD). A strong correlation was found between the average pore size of the starting material and the enzymatic conversion yield. The degree of crystallinity was maintained during enzymatic hydrolysis of the cellulosic substrates, contradicting previous explanations of the increasing crystallinity of cellulose during enzymatic hydrolysis. Both acid and enzymatic hydrolysis can increase the LFD, but no plausible mechanisms could be identified. The sample with the highest initial degree of crystallinity, NCC-OPHS-ND, exhibited the highest conversion yield, but this was not accompanied by any change in LFD, indicating that the hydrolysis mechanism is not based on lateral erosion.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0236-9) contains supplementary material, which is available to authorized users.

Preparation of oligochitosan via In situ enzymatic hydrolysis of chitosan by amylase in [Gly]BF4 ionic liquid/water homogeneous system

ABSTRACTThe preparation of oligochitosan with excellent performance via in situ enzymatic hydrolysis of chitosan by amylase in ionic liquid system is reported. It has been found that [Gly]BF4 ionic liquid leads to the good solubility and assistant degradation for chitosan, as well as good biocompatibility for amylase. In the homogeneous system that contained 1.0 g chitosan (degree of deacetylation = 88.5%) and 99.0 g 2 wt % [Gly]BF4 aqueous solution, oligochitosan with 2200 viscosity‐average molecular weight has been obtained after 0.12 g amylase being used for 3 h at 50°C and pH 5.0. This result is superior to that conducted in acetic acid system. Moreover, [Gly]BF4 can be easily separated from the product and reused with only slight performance loss (oligochitosan product with 2700 viscosity‐average molecular weight has been obtained after [Gly]BF4 being reused for five times). In addition, the mechanism for enzymatic hydrolysis of chitosan in [Gly]BF4 ionic liquid has been described. The research on the moisture‐absorption, ‐retention, and antibacterial activity of oligochitosan product shows that the smaller molecular weight would bring the better moisture‐absorption and antibacterial properties. The oligochitosan product with 2200 viscosity‐average molecular weight exhibits preferable antibacterial properties to S. aureus and E. coli. At the same time, the moisture‐absorption and ‐retention capacity of the above product can reach 32% (relative humidity (RH) = 43%), 62% (RH = 81%), and 150% (RH = 43%), 35% (dry silica gel) respectively. The enzymatic preparation of oligochitosan through [Gly]BF4 ionic liquid/water homogeneous system can be an efficient and environment‐friendly method for academics and industry. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41152.

Design and exploratory data analysis of a second generation of dendrimer prodrugs potentially antichagasic and leishmanicide

Chagas disease and leishmaniasis are neglected tropical diseases, considered as a serious public health. Also, the drugs available for their treatment are toxic and exhibit questionable efficacy. Consequently, the discovery and development of new drug candidates are currently necessary. Dendrimers are highly branched molecules with extremely controlled structure. Those molecular systems display several biological applications (i.e., drug carriers), especially when the focus is prodrug design. Herein, a second generation of dendrimer prodrugs was planned to obtain potentially antichagasic and leishmanicide delivery systems. These dendrimers were composed by myo-inositol (core), L-malic acid (spacer), and three bioactive agents [hydroxymethylnitrofurazone (NFOH), quercetin, 3-hydroxyflavone]. The major aim of this study was to investigate the molecular properties (thermodynamics, steric, steric/electronic, electronic, and hydrophobic) to further describe intersamples relationships through either similarity indices or linear combinations of the original variables. Then, an exploratory data analysis, which comprises hierarchical cluster analysis (HCA) and principal components analysis (PCA), was carried out. Complementary findings were observed for PCA and HCA. Steric, intrinsic/steric, steric/electronic, steric/hydrophobic, hydrophobic, and electronic properties influenced the discrimination process. In addition, these molecular properties can also contribute to enzymatic hydrolysis mechanism elucidation, which depends upon the approximation and a subsequent nucleophilic attack to release the drug from the dendrimer prodrugs.