RESUMO
Streptomyces globisporus 1912, a producer of the antitumor antibiotic landomycin E, forms the new low-molecular signaling molecule N-methylphenylalanyl-dehydrobutyrine diketopiperazine (BDD) and its complex and unstable by-product which restore, like the A-factor in Streptomyces griseus 773, landomycin E and streptomycin biosynthesis, and sporulation of the defective mutants S. globisporus 1912-B2 and S. griseus 1439, respectively. Here, we report the purification and structure elucidation of two compounds with R(f)0.8 by HPLC, LC/MS and 1HMR analysis. These compounds have m/z 338 and 384, accordingly, and each of them is presented by two stereoisomers containing BDD in their structure. A hypothesis explaining the composition and regulatory properties of these unstable compounds is presented.
Assuntos
Aminoglicosídeos/biossíntese , Fatores Biológicos/isolamento & purificação , Piperazinas/isolamento & purificação , Streptomyces/metabolismo , Aminoglicosídeos/genética , Antibióticos Antineoplásicos , Fatores Biológicos/biossíntese , Fatores Biológicos/farmacologia , Cromatografia Líquida de Alta Pressão , Meios de Cultura , Espectrometria de Massas , Peso Molecular , Mutação , Ressonância Magnética Nuclear Biomolecular , Piperazinas/metabolismo , Piperazinas/farmacologia , Transdução de Sinais/genética , Estereoisomerismo , Streptomyces/efeitos dos fármacos , Streptomyces/genéticaRESUMO
Fluorescence properties of 3-thiazolylchromones (TC) were studied in the wide H(0)/pH range -10 to 12. It was found that the number of the excited TC protolytic forms exceeds their quantity in the ground state. The formation of the new emitting species was explained as the result of the dramatic changes in the acid-base characteristics of three protolytic centers of TC molecules under the electronic excitation. The quantum chemical evaluation of the relative thermodynamic stability of all the possible excited TC acid-base forms aiming to find out, which of them should be the most energetically favorable, was made. The assignment of the experimentally observed emission bands to the above mentioned acid-base forms of 3-thiazolylchromones was carried out. The pH/H(0) ranges, where all of the detected protolytic forms could be observed, were determined. The dissociation and protonation constants of 3-thiazolylchromones in the ground and excited states were estimated. The most probable mechanism of the excited TC cation-tautomer formation was discussed.
