• BMB Reports
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• v.37 no.6
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• pp.642-647
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• 2004

The lysine residues of Bacillus licheniformis $\alpha$-amylase (BLA) were chemically modified using citraconic anhydride or succinic anhydride. Modification caused fundamental changes in the enzymes specificity, as indicated by a dramatic increase in maltosidase and a reduction in amylase activity. These changes in substrate specificity were found to coincide with a change in the cleavage pattern of the substrates and with a conversion of the native endo- form of the enzyme to a modified exo- form. Progressive increases in the productions of $\rho$-nitrophenol or glucose, when para nitrophenyl-maltoheptaoside or soluble starch, respectively, was used as substrate, were observed upon modification. The described changes were affected by the size of incorporated modified reagent: citraconic anhydride was more effective than succinic anhydride. Reasons for the observed changes are discussed and reasons for the effectivenesses of chemical modifications for tailoring enzyme specificities are suggested.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.888-901
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• 1996

Oxidations of cyclopentene and of 1-pentene with air have been studied on a V/Mo/P/Al/Ti-mixed oxide catalyst in a fixed bed integral reactor. At high levels of conversion maleic anhydride was in each case produced as the major organic product, along with minor amounts of phthalic anhydride and, only starting from 1-pentene, also of citraconic anhydride. At lower levels of conversion a total of 30 organic products have been identified, some of which may be intermediates on the way from the substrates to the three anhydrides mentioned above. Based on the dependence of selectivities of the organic products on conversion, reaction schemes for the formation of maleic anhydride, phthalic anhydride and citraconic anhydride have been proposed. Oxidation at $310^{\circ}C$ led to increasing conversions and selectivities for maleic anhydride with decreasing space velocities. The highest selectivities for maleic anhydride were obtained at conversion of ca. 100%. Oxidation at a constant space velocity of $2{\cdot}10^4h^{-1}$ led to increasing conversions with increasing temperatures in the range of $300^{\circ}C{\sim}420^{\circ}C$, while the selectivity for maleic anhydride passed through a maximum value of ca. 39% at $370^{\circ}C$ in the oxidation of cyclopentene and a maximum value of ca. 30% at $400^{\circ}C$ in the oxidation of 1-pentene.

• Korean Journal of Medicinal Crop Science
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• v.15 no.3
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• pp.143-147
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• 2007

The fruit flesh of four Prunus mume cultivated varieties, P. mume 'Nanko', P. mume 'Viridicalyx', P. mume 'Baigo', P. mume var, microcarpa 'Koshusaisho' Siebold & Zuccarni, were ground and extracted with ethyl acetate and their chemical components were analyzed by GC/MS-SIM. In the ten compounds which was used fer the calibration, maleic anhydride, citraconic anhydride, 5-hydroxymethylfurfural, vanillin, linoleic acid, ethyl linoleate, and squalene were determined in all the four cultivated varieties. However, palmitic acid was detected only in P. mume var. microcarpa 'Koshusaisho'. Isopropyl palmitate was found only in P. mume 'Baigo' and var, microcarpa 'Koshusaisho', while stearic acid was determined in P. mume 'Nanko', 'Viridicalyx', and var, microcarpa 'Koshusaisho'. In the variation of quantities, maleic anhydride was contained 245.4, 153.6, 20.1, and 2.7 ppm in P. mume 'Baigo', 'Nanko', var. microcarpa 'Koshusaisho', and 'Viridicalyx', respectively. Citraconic anhydride was also contained 637.4, 543.1, 150.7, and 38.7 ppm in P. mume 'Baigo', 'Nanko', var. microcarpa 'Koshusaisho', and 'Viridicalyx', respectively. The amounts of stearic acid were 105.5, 64.4, and 32.3 ppm in P. mume var. microcarpa 'Koshusaisho', 'Viridicalyx', and 'Nanko', respectively. Squalene was found in amounts of 7.6, 1.7, 1.0, and 0.5 ppm in P. mume var. microcarpa 'Koshusaisho', 'Baigo', 'Nanko', and 'Viridicalyx', respectively. The amounts of other minor compounds also were varied in the P. mume cultivated varieties.

• YAKHAK HOEJI
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• v.58 no.6
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• pp.371-377
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• 2014

A new series of 3-alkylthio-6-allylthio-4(or 5)-methylpyridazines (6a-e)-(7a-e) was synthesized from citraconic anhydride (1) for development of candidates possessing anticancer activity. The process involves the formation of pyridazine ring, dichlorination, monoallythiolation, and further another alkylthiolation. Compounds 6a-e, and 7a-e were prepared from 6-allylthio-3-chloro-4-methylpyridazine (4) or 6-allylthio-3-chloro-5-methylpyridazine (5) via nucleophilic substitution reaction with alkylthiol anion as nucleophile. Intermediates 4, and 5 could be converted to target pyridazines 6a-e, and 7a-e using 1~1.5 equivalent of alkylthiol at reflux temperature in methanol in the presence of sodium hydroxide. The structures of the synthetic compounds were characterized using NMR, IR, and GC-MS analyses.