• Bulletin of the Korean Chemical Society
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• v.18 no.4
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• pp.374-379
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• 1997

The rate constants for the nucleophilic addition of thiophenol derivatives (p-OCH3, H, p-CH3, m-CH3, p-Br and p-NO2) to 4'-[N-(9-acridinyl)]-1'-(N-methanesulfonyl)-3'-methoxyquinonediimide (AMQD) were determined by ultraviolet spectrophotometer in water at 5 ℃, and rate equations which can be applied over a wide pH range were obtained. On the basis of pH-rate profile, Bronsted plot, adduct analysis, general base catalysis and substituent effect, a plausible mechanism of this addition reaction was proposed: Below pH 2.5, the reaction proceeded by the addition of thiophenol molecule to 6'-position of quinonoid after protonation at the acridinyl nitrogen. Above pH 6.2, the addition of sulfide anion to 6'-position of quinonoid was rate controlling. However, in the range of pH 3.0-6.0, these two reactions occured competively.

• Journal of Pharmaceutical Investigation
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• v.19 no.4
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• pp.213-217
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• 1989

To formulate the stable preparation of Gingko extract injection and to evaluate the stability of the preparation, Gingko extract aqueous solutions having various pH values were prepared and the stability of ginskoflavonglycoside (GFG) was investlfated by high performance liquid chromatography. The stability of GFG decreased as pH increased, while the water solubility of Gingko extract decreased as pH decreased. The optimal pH of the Gingko extract aqueous solution was found to be pH 6.5. The shelf life $(T_{90%})$ of the Gingko extract aqueous solution of pH 6.5 at $20^{\circ}C$ was extrapolated to be four years.

• Bulletin of the Korean Chemical Society
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• v.6 no.5
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• pp.280-284
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• 1985

Kinetic measurements of the 5-nitrofurfural-hydrazine reaction in various pH ranges of aquous solution were carried out by ultraviolet spectrophotometry at $25^{\circ},\;35^{\circ}\;and\;45^{\circ}C$. The observed rate of the reaction varies with the change in pH, which gives characteristic "bell-type" rate acidity profile. The maximum rate is shown in the vicinity of pH 4. This reaction procceds with rate-determining attack of hydrazine on the 5-nitrofurfural at low pH and undergoes a change in rate-determining step to dehydration of the addition intermediate as pH increases. The reaction has a "reactant-like transition state" which precedes intermediate in low pH and "product-like transition state" which follows it in neutral pH. The geometry of 5-nitrofurfural-hydrazine intermediate was estimated with PCILO method associated with CNDO/2 scheme.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1227-1228
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• 2010

• Journal of Microbiology and Biotechnology
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• v.20 no.12
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• pp.1696-1701
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• 2010

The ${\alpha}$-amylases activity was improved by random mutagenesis and screening. A region comprising residues from the position 34-281 was randomly mutated in B. licheniformis ${\alpha}$-amylase (AmyL), and the library with mutations ranging from low, medium, and high frequencies was generated. The library was screened using an effective liquid-phase screening method to isolate mutants with an altered pH profile. The sequencing of improved variants indicated 2-5 amino acid changes. Among them, mutant TP8H5 showed an altered pH profile as compared with that of wild type. The sequencing of variant TP8H5 indicated 2 amino acid changes, Ile157Ser and Trp193Arg, which were located in the solvent accessible flexible loop region in domain B.

• Korean Journal of Veterinary Research
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• v.29 no.2
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• pp.59-67
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• 1989

This paper deals with the genetic properties of R plasmids in Salmonella originated from pigs and cattle. The plasmid DNA was examined for incompatibility, stability and fertility inhibition(Fi), and gel electrophoresis was performed for isolation of plasmid DNA. The results obtained were summerized as follows: 1. Among the 66 conjugative R plasmids from 44 pigs and 22 cattle, 61 R plasmids (92.4%) were $Fi^-$, whereas the remainder were $Fi^+$. 2. The Inc groups of 66 R plasmids were determined with 7 standard plasmids. Twenty-six R plasmids were classified into Inc group $I{\alpha}$, H1, H2 or F1, 40 R plasmids being not classified with standard plasmids used, and the Inc group $I{\alpha}$ (57.7%) was most frequent. 3. Inc groups $I{\alpha}$, H1, and F1 were identified in strains from swine, Inc groups H2 and F1 from cattle. 4. The plasmid DNA profiles in 16 Salmonella isolated from pigs and cattle were confirmed as being 1 to 10 fragments by the gel eletrophoresis. Their molecular weight ranged 1.0 to 90 megadalton. 5. The molecular weight of conjugative plasmids ranged 1.0 to 80 megadalton in 4 Salmonella (P-4, P-5, P-7 and P-8) isolated from pigs.

• BMB Reports
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• v.40 no.3
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• pp.315-324
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• 2007

The novel $\alpha$-amylase purified from locally isolated strain, Bacillus sp. KR-8104, (KRA) (Enzyme Microb Technol; 2005; 36: 666-671) is active in a wide range of pH. The enzyme maximum activity is at pH 4.0 and it retains 90% of activity at pH 3.5. The irreversible thermoinactivation patterns of KRA and the enzyme activity are not changed in the presence and absence of $Ca^{2+}$ and EDTA. Therefore, KRA acts as a $Ca^{2+}$-independent enzyme. Based on circular dichroism (CD) data from thermal unfolding of the enzyme recorded at 222 nm, addition of $Ca^{2+}$ and EDTA similar to its irreversible thermoinactivation, does not influence the thermal denaturation of the enzyme and its Tm. The amino acid sequence of KRA was obtained from the nucleotide sequencing of PCR products of encoding gene. The deduced amino acid sequence of the enzyme revealed a very high sequence homology to Bacillus amyloliquefaciens (BAA) (85% identity, 90% similarity) and Bacillus licheniformis $\alpha$-amylases (BLA) (81% identity, 88% similarity). To elucidate and understand these characteristics of the $\alpha$-amylase, a model of 3D structure of KRA was constructed using the crystal structure of the mutant of BLA as the platform and refined with a molecular dynamics (MD) simulation program. Interestingly enough, there is only one amino acid substitution for KRA in comparison with BLA and BAA in the region involved in the calcium-binding sites. On the other hand, there are many amino acid differences between BLA and KRA at the interface of A and B domains and around the metal triad and active site area. These alterations could have a role in stabilizing the native structure of the loop in the active site cleft and maintenance and stabilization of the putative metal triad-binding site. The amino acid differences at the active site cleft and around the catalytic residues might affect their pKa values and consequently shift its pH profile. In addition, the intrinsic fluorescence intensity of the enzyme at 350 nm does not show considerable change at pH 3.5-7.0.

• Food Science of Animal Resources
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• v.44 no.3
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• pp.635-650
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• 2024

In this study, we analyzed the physicochemical and sensory properties of black goat jerky marinated with various spices (non-spice, control; rosemary, RO; basil, BA; ginger, GI; turmeric, TU; and garlic, GA). The physicochemical properties of black goat jerky analyzed were pH, water holding capacity, color, cooking yield, shear force, and fatty acid composition. The sensory characteristics were analyzed through the aroma profile (electronic nose), taste profile (electronic tongue), and sensory evaluation. The pH and water holding capacity of the GI showed higher values than the other samples. GI and GA showed similar values of CIE L^* and CIE a^* to that of the control. The shear force of the GI and TU was significantly lower than that of other samples (p<0.05). Regarding fatty acid composition, GI showed high unsaturated and low saturated fatty acid contents compared with that of the other samples except for RO (p<0.05). In the aroma profile, the peak area of hexanal, which is responsible for a faintly rancid odor, was lower in all treatment groups than in the control. In the taste profile, the umami of spice samples was higher than that of the control, and among the samples, GI had the highest score. In the sensory evaluation, the GI sample showed significantly higher scores than the control in terms of flavor, aroma, goaty flavor, and overall acceptability (p<0.05). Therefore, marinating black goat jerky with ginger powder enhanced the overall flavor and reduced the goat odor.

• Asian Journal of Turfgrass Science
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• v.9 no.1
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• pp.75-80
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• 1995

In eight golf courses of southern area fair way soil profile was investigated for soil physical, chemical properties, and root distribution. These were carried out only A horizon(lScm depth) in one golf course. Soil series was all different, Leaching to lower horizon was greator in order of Mg=$NO_3$> $NH_4$=Ca> K. Organic matter content was higher in B horizon than A in three golf courses. Soil phosphorus appeared to more down greatly in two golf courses. Soil pH was higher in lower horizon of all places. Such pH increase with depth seemed to he related with mineral leaching, Among the horizons of all golf courses BC showed significant correlation with K (EC =0.1025K +0.0157, r=0. 8012 p=0. 001 n=20). Both Fe and Mn were higher in A horizon.

• Bulletin of the Korean Chemical Society
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• v.24 no.3
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• pp.306-310
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• 2003

Hydrolysis reactions of S-phenyl-S-vinyl-N-p-tosylsulfilimine (VSI) and its derivatives at various pH have been investigated kinetically. The hydrolysis reactions produced phenylvinylsulfoxide and p-toluene sulfonamide as the products. The reactions are first order and Hammett ρ values for pH 1.0, 6.0, and 11.0 are 0.82, 0.45, and 0.57, respectively. This reaction is not catalyzed by general base. The plot of k vs pH shows that there are three different regions of the rate constants $(k_t)$ in the profile.; At pH < 2 and pH > 10, the rate constants are directly proportional to the concentrations of hydronium and hydroxide ion catalyzed reactions, respectively. The rate constant remains nearly the same at 2 < pH < 10. On the bases of these results, the plausible hydrolysis mechanism and a rate equation have been proposed: At pH < 2.0, the reaction proceeds via the addition of water molecule to sulfur after protonation at the nitrogen atom of the sulfilimine, whereas at pH > 10.0, the reaction proceeds by the addition of hydroxide ion to sulfur directly. In the range of pH 2.0-10.0, the addition of water to sulfur of sulfilimine appears to be the rate controlling step.