Hydrolysis of wheat starch and its effect on the falling number procedure: mathematical model

A population balance model was developed for wheat starch hydrolysis to simulate the performance parameters of a viscosity-based device, known as the Falling Number instrument. The instrument is widely used as an indirect means to gauge the level of preharvest sprout activity in cereal grains such as wheat and barley. The model consists of three competing kinetics: starch gelatinization, enzymatic hydrolysis, and enzyme thermal deactivation. Using established principles of starch rheology and fluid mechanics, the model simulates the velocity profiles of the falling stirrer, starch gel viscosity, and the Falling Number readings at various levels of alpha-amylase. Model predictions for the velocity of the stirrer at any time during the downward fall, as well as the prediction of the total time needed for the fall, defined as the Falling Number, were in fair agreement with experimental measurements. There was better agreement between the modeled viscosity and the final viscosity of the starch gel as measured by a precision rheometer than there was with the measured Falling Number.     

Kinetic resolution of 1-chloro-3-(1-naphthyloxy)-2-propanol,an intermediate in the synthesis of beta-adrenergic receptor blockers

(R)- and (S)-1-chloro-3-(1-naphthyloxy)-2-propanol are intermediates in the synthesis of β-adrenergic blocking agents and antihypertensive drugs such as propranolol and nadoxolol. Herein, improvement in the preparation of racemic 1-chloro-3-(1-naphthyloxy)-2-propanol generated from 1-naphthol and epichlorohydrin are reported. In addition, kinetic resolution studies have been conducted to obtain both (R) and (S)-1-chloro-3-(1-naphthyloxy)-2-propanol. These compounds were obtained in highly optically pure form by the stereoselective hydrolysis of its acyl derivatives using whole cell preparations containing enzymes from native sources. The results were compared with those obtained using commercial lipases.     

Colorimetric chiral fluorescent sensors for Eu3+ and sequential enantioselective sensing of malate anion

Novel phenanthroline Schiff base fluorescent sensors L1 , L2 , and D1 were designed and synthesized. The sensing abilities of the compounds in the presence of metal cations (Li⁺, Na⁺, K⁺, Ag⁺, Mg²⁺, Ba²⁺, Ca²⁺, Mn²⁺, Pb²⁺, Hg²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Co²⁺, Cu²⁺, Cr³⁺, Fe³⁺, Fe²⁺, Al³⁺, and Eu³⁺) were studied by UV‐vis and fluorescent spectroscopy. The compounds L1 , L2 , and D1 could act as Eu³⁺ ion turn‐off fluorescent sensors based on ligand‐to‐metal binding mechanism in DMSO‐H₂O solution (v/v = 1:1, 10 mM Tris, pH = 7.4). Additionally, the L1 –Eu³⁺ and D1 –Eu³⁺ complexes could be applied as turn‐on enantioselective sensors sensing of malate anion isomers with color changes. Furthermore, biological experiments using living PC‐12 cells demonstrated that L1 and D1 had excellent membrane permeability and could be used as effective fluorescent sensors for detecting Eu³⁺ and malate anion in living cells.     

Disruption of Potential α-Helix in the G Loop of the Guinea: Pig 5-Hydroxytryptamine2 Receptor Does Not Prevent Receptor Coupling to Phosphoinositide Hydrolysis

Abstract: Heterogeneity of the 5-hydroxytryptamine₂ (5-HT₂) receptor across species has been implicated in several pharmacological and physiological studies. Although 5-HT₂ receptors in the rat have been linked to increases in Phosphoinositide (PI) hydrolysis, little evidence exists to support the association of guinea pig 5-HT₂ receptors with Pl hydrolysis, the second messenger generally linked with 5-HT₂receptors. In the present study, we have taken a molecular and biochemical approach to determining whether species differences in brain 5-HT₂ receptors exist between rat and guinea pig. First, we isolated partial cortical 5-HT_a receptor cDNA clones that encompassed the third intracellular loop, a receptor area putatively important in receptor-effector coupling. The amino acid sequences deduced from the cDNA clones for rat and guinea pig brain 5-HT₂ receptor were 97% homologous. However, the guinea pig 5-HT₂ receptor had two tandem substitutions that disrupted a potential alpha helix in the region of the third cytoplasmic loop, which theoretically could alter the intracellular coupling of the guinea pig cortical 5-HT₂ receptor. Because of these molecular differences, we examined further the pharmacological activation of the brain 5-HT₂ receptor from guinea pig. 5-HT and the 5-HT₂ receptor agonist α-methyl-5-HT increased PI hydrolysis in guinea pig cortical slices whereas the 5-HT_1c receptor agonist 5-methyltryptamine was significantly less potent. In addition, the 5-HT₂ receptor antagonists LY53857, ketanserin, and spiperone blocked 5-HT-stimulated Pl hydrolysis. These pharmacological data suggested that activation of the 5-HT₂ receptor in guinea pig cortical slices was associated with PI hydrolysis. Thus, although areas of the guinea pig brain 5-HT₂ receptor that influence receptor-effector coupling were different from the rat, such differences were not critical to receptor-effector coupling because, as in the rat, guinea pig brain 5-HT₂ receptors were also coupled to PI hydrolysis.     

Effective production of N-acetyl-β-D-glucosamine bySerratia marcescens using chitinaceous waste

The strain ofSerratia marcescens QM B1466 produces selectively large amount of chitinolytic enzymes (about 1mg/L medium). Enzymatic hydrolysis of chitin to N-acetyl-β-D-glucosamine (NAG) was performed with a system consisting of two hydrolases (chitinase and chitobiase) produced by optimization of a microbial host consuming chitin particles. For the development of Large-scale biological process for the production of NAG from chitinaceous waste, the selection and optimization of a microbial host, particle size of chitin and pretreatment of chitin source were investigated. Also, the effect of crab/shrimp chitin sources and initial induction time using chitin as a sole carbon source on chitinase/chitobiase production and NAG production were examined. Crab-shell chitin(1.5%) treated by dilute acid and, ball-milled with a nominal diameter less than 250m gave the highest chitinase activity over a 7 days culture. Crude chitinase/chitobiase solution obtained in a 10 L fed-batch fermentation showed a maximum activities of 23.6 U/mL and 5.1 U/mL, respectively with a feeding time of 3 hrs, near pH 8.5 at 30°C.     

Neutral fat hydrolysis and long-chain fatty acid oxidation during anaerobic digestion of slaughterhouse wastewater

Neutral fat hydrolysis and long-chain fatty acid (LCFA) oxidation rates were determined during the digestion of slaughterhouse wastewater in anaerobic sequencing batch reactors operated at 25 degrees C. The experimental substrate consisted of filtered slaughterhouse wastewater supplemented with pork fat particles at various average initial sizes (D(in)) ranging from 60 to 450 microm. At the D(in) tested, there was no significant particle size effect on the first-order hydrolysis rate. The neutral fat hydrolysis rate averaged 0.63 +/- 0.07 d(-1). LCFA oxidation rate was modelled using a Monod-type equation. The maximum substrate utilization rate (kmax) and the half-saturation concentration (Ks) averaged 164 +/- 37 mg LCFA/L/d and 35 +/- 31 mg LCFA/L, respectively. Pork fat particle degradation was mainly controlled by LCFA oxidation rate and, to a lesser extent, by neutral fat hydrolysis rate. Hydrolysis pretreatment of fat-containing wastewaters and sludges should not substantially accelerate their anaerobic treatment. At a D(in) of 450 microm, fat particles were found to inhibit methane production during the initial 20 h of digestion. Inhibition of methane production in the early phase of digestion was the only significant effect of fat particle size on anaerobic digestion of pork slaughterhouse wastewater. Soluble COD could not be used to determine the rate of lipid hydrolysis due to LCFA adsorption on the biomass.     

Enantioselective liquid‐liquid extraction of 3‐chloro‐phenylglycine enantiomers using (S,S)‐DIOP as extractant

(S,S)‐DIOP, a common catalyst used in asymmetric reaction, was adopted as chiral extractant to separate 3‐chloro‐phenylglycine enantiomers in liquid‐liquid extraction. The factors affecting extraction efficiency were studied, including metal precursors, organic solvents, extraction temperature, chiral extractant concentration, and pH of aqueous phase. (S,S)‐DIOP‐Pd exhibited good ability to recognize 3‐chloro‐phenylglycine enantiomers, and the operational enantioselectivity (α) is 1.836. The highest performance factor (pf) was obtained under the condition of extraction temperature of 9.1°C, (S,S)‐DIOP‐Pd concentration of 1.7 mmol/L, and pH of aqueous phase of 7.0. In addition, the possible recognition mechanism of (S,S)‐DIOP‐Pd towards 3‐chloro‐phenylglycine enantiomers was discussed.     

Modeling and optimization of phospholipase A1‐catalyzed hydrolysis of phosphatidylcholine using response surface methodology for lysophosphatidylcholine production

Modeling the phospholipase A₁ (PLA₁)‐catalyzed partial hydrolysis of soy phosphatidylcholine (PC) in hexane for the production of lysophosphatidylcholine (LPC) and optimizing the reaction conditions using response surface methodology were described. The reaction was performed with 4 g of PC in a stirred batch reactor using a commercial PLA₁ (Lecitase Ultra) as the biocatalyst. The effects of temperature, reaction time, water content, and enzyme loading on LPC and glycerylphosphorylcholine (GPC) content in the reaction products were elucidated using the models established. Optimal reaction conditions for maximizing the LPC content while suppressing acyl migration, which causes GPC formation, were as follows: temperature, 60°C; reaction time, 3 h; water content, 10% of PC; and enzyme loading, 1% of PC. When the reaction was conducted with 40 g of PC under these conditions, the reaction products contained 83.7 mol % LPC and were free of GPC. LPC had a higher total unsaturated fatty acid content than original PC had and was mainly composed of linoleic acid (78.0 mol % of the total fatty acids). © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 31:35–41, 2015     

Enantioselective Degradation of Chiral Insecticide Dinotefuran in Greenhouse Cucumber and Soil

The enantioselective degradation behavior of the chiral insecticide dinotefuran in cucumber and soil was investigated under greenhouse conditions based on the method established with a normal‐phase high‐performance chromatography (HPLC) on a ChromegaChiral CCA column (250 × 4.6 mm, 5 µm, ES Industries). The linearity range, matrix effect, precision, and accuracy of the method were evaluated and the method was then successfully applied for the enantioselective analysis of dinotefuran in cucumber and soil. Significant enantioselectivity of degradation was observed in soil according to the results. The (+)‐dinotefuran was more persistent in soil with half‐life of 21.7 d, which is much longer than that of (–)‐dinotefuran (16.5 d). In cucumber, the (–)‐dinotefuran also tended to be preferentially degraded both in foliar and douche treatment. However, the statistical analysis indicated the enantioselectivity of degradation in cucumber was not significant. The research provides the first report concerning the enantioselective degradation of dinotefuran enantiomers and the results can be used for understanding the insect‐controlling effect and food safety evaluation. Chirality 27:137–141, 2015. © 2014 Wiley Periodicals, Inc.     

Enhancement of enzyme activity and enantioselectivity by cyclopentyl methyl ether in the transesterification catalyzed by <Emphasis Type="Italic">Pseudomonas cepacia</Emphasis> lipase co-lyophilized with cyclodextrins

The solvent effects of cyclopentyl methyl ether (CPME) on the reaction rates and enzyme enantioselectivity in the enantioselective transesterifications of racemic 6-methyl-5-hepten-2-ol (racemic sulcatol: SUL) and racemic 2,2-dimethyl-1,3-dioxolane-4-methanol (racemic solketal: SOL) with a series of enol esters catalyzed by Pseudomonas cepacia lipase co-lyophilized with cyclodextrins (-, -, -, partially methylated -,and 2,3,6-tri-O-methyl--cyclodextrin: CyD; CyD; CyD; Me_1.78 CyD; Me₃CyD) were investigated and compared with those in diisopropyl ether (IPE). In the case of SUL, enzyme activities of the co-lyophilizate with Me_1.78 CyD in CPME were lower than those in IPE with every acyl source, however, the absolute enantiopreference was shown in the transesterification with vinyl butyrate (VBR) in IPME. When the substrates were SOL and VBR, the enzyme activities in CPME were greatly enhanced as high as 1.6–9.8-fold, while the enantioselectivities in CPME were comparable to those in IPE.Revisions requested 16 December 2004; Revisions received 17 January 2005