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Applied Biochemistry and Biotechnology: Part A: Enzyme Engineering and Biotechnology (v.104, #1)
Continuous oxygen monitoring of mammalian cell growth on space shuttle mission STS-93 with a novel radioluminescent oxygen sensor by Julie S. Reece; Michael J. Miller; Mark A. Arnold; Cris Waterhouse; Ted Delaplaine; Laura Cohn; Tom Cannon (pp. 1-11).
A compact, flow-through oxygen sensor device based on luminescence quenching was used to monitor dissolved oxygen levels during mammalian cell growth on the STS-93 mission of the Columbia space shuttle. Excitation of an oxygen-sensitive ruthenium complex was provided by a radiolumin escent light source (0.9 mm in diameter, 2.5 mm long), and the intensity of the resulting luminescence was measured by a simple photodiode detector. The use of radiolum inescence for the excitation light source is a unique approach that provides many features important for long-term and remote monitoring applications. For the spaceflight experiment, human lung fibroblast cells (WI-38) were grown in hollow-fiber bioreactors. Oxygen concentration was measured in the flow path both before and after the bioreactor cartridge in order to gain information about the metabolism of the cells. The sensor was found to be nonperturbing to cell growth and withstood the challenging physical conditions of shuttle launch and landing while maintaining a stable calibration function. In addition, the sensor provided physically meaningful oxygen predictions.
Keywords: Oxygen sensors; optical sensors; ruthenium fluorescence quenching; radioluminescence; spaceflight monitoring; bioreactor monitoring
Sulfated polysaccharides from red microalgae have antiinflammatory properties in vitro and in vivo by Mary S. Matsui; Neelam Muizzuddin; Shoshana Arad; Kenneth Marenus (pp. 13-22).
The primary goal of the present research was to determine whether sulfated polysaccharides derived from red microalgae possess anti inflammatory properties when directed against specific parameters of human skin inflammation. These unique biopolymers were studied in both in vitro and in vivo models of skin inflammation. Human subjects were recruited to participatein a study in which the polysaccharide material was applied topically and shown to inhibit cutaneousery thema induced by a known irritant. Leukocyte migration from capillary blood intosites of inflammation is an essential component of the inflammatory process and occurs in a series of steps, two of which are adhesion and chemotaxis. In vitro, the polysaccharide material primarily inhibited the migration of polymorphonuclear leukocytes (PMNs) toward a standard chemoattractant molecule and also partially blocked adhesion of PMNs to endothelial cells. The data obtained strongly suggest that sulfated polysaccharides derived from red microalgae have significant beneficial potential for use in topical products. In addition, the data suggested that the anti inflammatory mechanism for the polysaccharide was, at least in part, due to inhibition of circulating immune cell recruitment toward inflammatory stimuli.
Keywords: Polysaccharide; algae; chemotaxis; cutaneous inflammation; topical anti inflammatory; dermatitis
Effect of freeze-dried immobilized cells on delignified cellulosic material in low-temperature and ambient-temperature wine making by M. Ikonomopoulou; M. Kanellaki; M. Soupioni; A. A. Koutinas (pp. 23-36).
In this article, were port on wine making by freeze-dried immobilized cells on delignified cellulosic material for ambient and low temperatures. Biocatalyst supported by freeze-dried delignified cellulosic (FDC) material recovered after the first repeated-batch fermentations the fermentation efficiency and startup, which become about equal to those of biocatalyst supported by wet delignified cellulosic material. The FDC biocatalyst was suitable for wine making at low temperatures (5–15°C), and produced wine of 12% alcoholic degree, with the main volatiles contained in the wine and reduced by a decrease in temperature. The fermentation efficiency was not affected by total acidity of must, while an increase in initial Be density improved percentages of higher alcohols and ethylacetate. The quality of the wine was validated by a preliminary taste test to be in the range of acceptable to excellent.
Keywords: Freeze drying; immobilization; wine making; delignified cellulosics; low-temperature fermentation
Pretreatment of corn stover using wet oxidation to enhance enzymatic digestibility by Enikő Varga; Anette S. Schmidt; Kati Réczey; Anne Belinda Thomsen (pp. 37-50).
Corn stover is an abundant, promising raw material for fuel ethanol production. Although it has a high cellulose content, without pretreatment it resists enzymatic hydrolysis, like most lignocellulosic materials. Wet oxidation (water, oxygen, mild alkali or acid, elevated temperature and pressure) was investigated to enhance the enzymatic digestibility of corn stover. Six different combinations of reaction temperature, time, and pH were applied. The best conditions (60g/L of corn stover, 195°C, 15 min, 12 bar O2, 2 g/L of Na2CO3) increased the enzymatic conversion of corn stover four times, compared to untreated material. Under these conditions 60% of hemicellulose and 30% of lignin were solubilized, whereas 90% of cellulose remained in the solid fraction. After 24-h hydrolysis at 50°C using 25 filter paper units (FPU)/g of dry matter (DM) biomass, the achieved conversion of cellulose to glucose was about 85%. Decreasing the hydrolysis temperature to 40°C increased hydrolysis time from 24 to 72 h. Decreasing the enzyme loading to 5 FPU/g of DM biomass slightly decreased the enzymatic conversion from 83.4 to 71%. Thus, enzyme loading can be reduced without significantly affecting the efficiency of hydrolysis, an important economical aspect.
Keywords: Corn stover; wet oxidation; slurry; filter cakes; enzymatic convertible cellulose; enzymatic digestibility
Modeling of the hydrolysis of sugar cane bagasse with hydrochloric acid by Guadalupe Bustos; José Alberto Ramírez; Gil Garrote; Manuel Vázquez (pp. 51-68).
Sugar cane bagasse was hydrolyzed under different concentrations of hydrochloric acid (2–6%), reaction times (0–300 min), and temperatures (100–128°C). Sugars obtained (xylose, glucose, arabinose, and glucose) and deg-radation products (furfural and acetic acid) were determined. Based on the Saeman model and the two-fraction model, kinetic parameters for predicting these compounds in the hydrolysates were developed. The influence of temperature was studied using the Arrhenius equation. The optimal conditions selected were 128°C, 2% HCl, and 51.1 min. Using these conditions, 22.6g xylose/L, 3.31 garabinose/L, 3.77 g glucose/L, 3.59 g acetic acid/L, and 1.54 g furfural/L were obtained.
Keywords: Sugar cane; bagasse; xylose; modeling; acid hydrolysis
Isolation of lipase producer and its performance in enantioselective hydrolysis of glycidyl butyrate by Shi-Ying Jia; Jian-He Xu; Qing-Shan Li; Jun-Tang Yu (pp. 69-79).
A racemic glycidyl butyrate resolving strain, preliminarily identified as a Rhizopus sp., had been isolated from soil. Its extracellular lipase was found to enantioselectively hydrolyze the (S)-enantiomer of the chiral ester, with optimal activities at pH 5.3 and 42°C. Higher en antioselectivity of theenzyme was observed at lower temperatures, while the best anantioselectivity was obtained at pH 5.5–6.0, with an, E value (enantiomeric ratio) of 57.
Keywords: (R, S.)-Glycidyl butyrate; optical resolution; lipase; Rhizopus sp; isolation
Effect of Mn2+, Co2+, Ni2+, and Cu2+ on horseradish peroxidase by A. Mahmoudi; K. Nazari; N. Mohammadian; A. A. Moosavi-Movahedi (pp. 81-94).
The effects of transition metal ions (M2+) such as Mn2+, Co2+, Ni2+, and Cu2+ on the functional and structural stabilities of horseradish peroxidase (HRP) were investigated with respect to reversible chemical denaturation, Michaelis-Menten kinetics, chemical modification and time-dependent catalytic activity. Conformational Gibbs free energy (ΔG°(H2O)) as a structural stability criterion and transition concentrations of metal ions ([M2+]1/2) were estimated using a two-state chemical denaturation model. Activation and inhibitory concentration ranges for each metal ion were specified by the steady-state enzyme kinetics. Results of a pH-profile method confirmed by chemical modification indicate that a histidine residue interacts in the activation concentration range, whereas carboxylic residues (Asp and Glu) contribute to interaction in the inhibitory concentration range. Incubation of the enzyme with the metal ion at activation concentration leads to long-term functional stability of peroxidase. Thus, such metal ions as potent effectors induced the enhancement of conformational and functional stabilities of horseradish peroxidase.
Keywords: Horseradish peroxidase; transition metal ions; activation; inhibition; denaturation; functional stability