金沢大学附属図書館 OPAC plus

概要: 2-(2-Thiazolylazo)-4-methoxyphenol (TAMP) forms a brownish 2:1 complex with iron(ll) in the presence of ascorbic acid; t … he complex has a characteristic absorption at 784 nm in chloroform. By utilizing this peculiar absorption, selective spectrophotometry determination of iron has been developed. The optimum pH for iron extraction lies between 5.0-9.3 and Beer's law holds up to 5.0 ng/ml of iron. Many type of ions are tolerable. The method was successfully applied to the determination of iron in river waters. The extraction constant of iron(ll) complex was log Kex=-2.50±0.12 and the extraction mechanism was kinetically investigated. The complexation rate was first-order with respect to iron(ll) and TAMP concentrations and independent of ascorbic acid concentration. From these results, the major extraction rate-determining step was concluded to be a 1:1 complexation reaction between iron(ll) and dissociated TAMP. Kinetic data and activation parameters for the first-order reaction were determined and discussed. © 1988, The Japan Society for Analytical Chemistry. All rights reserved. 続きを見る

概要: Three new metabolites, named macommelinal, macrophin and macrophic acid, were isolated from the culture broth of Macrophoma commelinae IFO 9570. Their structures were determined to be … 2-(4-methoxy-6-methyl-2-oxo-2H-pyran-5-yl)ethanal, 3-methyl-2-butenoic acid (E)-[5-hydroxymethyl-4-methoxy-6-(2-methoxycarbonylethenyl)-2-oxo-2H-pyran-3-ly]methyl ester and 3-(4-methoxy-3,5-dimethyl-2-oxo-2H-pyran-6-yl)-2-propenoic acid, respectively. 4 Acetyl-3-methoxy-5-methylbenzoic acid, now named macrophomic acid, was also isolated from a large-scale culture.The biosynthesis of the macommelin group, novel 5-substituted 2-pyrone metabolites, has been investigated by feeding experiments with [1-^<13>C]-, [1,2-^<13>C_2]- and [1-^<13>C, 2-^2H_3]acetate and [2-^<13>C]malonate. It was concluded that all these metabolites originated from a single straight tetraketide chain. Furthermore, the biogenetic mutual relationships of these metabolites including potential intermediates were estabished through incorporation experiments with ^<14>C-labeled compounds. 続きを見る

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