• Microbiology and Biotechnology Letters
• /
• v.7 no.3
• /
• pp.135-140
• /
• 1979

A Streptomyces sp. strain AS-727 which was capable of producing penicillinase, was isolated from soil. The enzyme production was affected by the carbon and nitrogen sources added. Among them so far tested, glucose (or maltose) and sodium nitrate increased the enzyme production. And the amount of enzyme prodced reached maximum in 4 days cultivation. The optimla pH and temperature of the penicillinase was between pH 6.0 to 8.0 and 4$0^{\circ}C$ respectively. The stabel pH range of the enzyme was stable at 4$0^{\circ}C$, but it lost about 30％ and 40％ of the the activity respectively when it was treated at 6$0^{\circ}C$ and 8$0^{\circ}C$ for 60 minutes. The activity of the enzyme was inhibited by Z $n^{++}$, but A $g^{+}$, $Co^{++}$, $_Mn^{++}$, $Ca^{++}$, P $b^{++}$ did not affected enzyme activity. Peculiarly, the enzyme protein precipitated by freezing or addition of ammonium sulfate, urea, sodium chloride and some organic solvents as etanol, methanol, acetone was not dissolved in deionized water or any buffer solution.n.n.ion.n.n.

• Applied Biological Chemistry
• /
• v.38 no.5
• /
• pp.455-462
• /
• 1995

The new six herbicidal N-[(pyrimidin-2-yl)aminocarbonyl]-2-substituted-6-(1-hydroxy-2-fluoroethyl)benzenesulfonamide derivatives(S) were synthesized and rate constants for the hydrolysis of thier in the range of pH $1.0{\sim}10.0$ have been studied in 15%(v/v) aqueous acetonitrile solution at $45^{\circ}C$. From the basis of the results, pH-effect, solvent effect, ortho-substituent effect, thermodynamic parameters(${\Delta}H^{\neq}$ & ${\Delta}S^{\neq}$), pKa constant(4.80), rate equation, analysis of hydrolysis products(2-(1-hydroxy-2-fluoroethyl)benzenesulfonamide & 4,6-dimethoxyaminopyrimidine), it may be concluded that the general acid catalyzed hydrolysis through $A-S_E2$ mechanism and specific acid catalyzed hydrolysis through A-2 type(or $A_{AC}2$) mechanism proceeds via conjugate acid($SH^+$) and tetrahedral intermediate(I) below pH 8.0, whereas, above pH 9.0, the general base catalyzed hydrolysis by water molecules(B) through $(E_1)_{anion}$ mechanism proceeds via conjugate base(CB). In the range between $pH\;7.0{\sim}pH\;9.0$, these two reactions occur competitively.

• Korean Journal of Soil Science and Fertilizer
• /
• v.39 no.1
• /
• pp.38-45
• /
• 2006

Movement of nitrate ($NO_3-N$) through a soil profile under no tillage (NT) or conventional tillage (CT) practices was monitored to identify the effects of tillage systems on nitrate leaching and retention in the soil profile at two commercial farms in central Illinois from 1993 through 1994. Anhydrous ammonia was applied in the 1993 growing seasons, while a mixture of urea and ammonium nitrate solution (URAN) was applied in three separate applications during the spring and early summer of the 1994 season. $NO_3-N$ of each plot through a 100 cm soil depth was found to be significantly high around $20mg\;kg^{-1}$ soil in the early 1993 season. However, downward movement of $NO_3-N$ occurred during the growing season. At the end of growing season, Flanagan and Ipava soils generally retained more $NO_3-N$ through the soil profile for both the CT plots and the NT plots than the Saybrook and Catlin soils. However, there was no significant difference between the nitrate content of the two soil types in each year. $NO_3-N$ content in NT fields were slightly higher than that observed in CT fields throughout the season before harvest. It means that NT plots may reduce the nitrate leaching to the ground water.