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Abstract Background Putrescine is the intermediate product of arginine decarboxylase pathway in Escherichia coli which can be used as an alternative nitrogen source. Transaminase and dehydrogenase enzymes seem to be implicated in the degradative pathway of putrescine, in which this compound is converted into γ-aminobutyrate. But genes coding for these enzymes have not been identified so far. Results The 1.8-kbp DNA fragment containing E. coli K12 ygjG gene with aer-ygjG intergenic region was examined. It was found that the fragment contains σ54-depended open reading frame (ORF) of 1,380 nucleotides encoding a 459-amino acid polypeptide of approximately 49.6 kDa. The cytidine (C) residue localized 10 bp downstream of the σ54 promoter sequence was identified as the first mRNA base. The UUG translation initiation codon is situated 36 nucleotides downstream of the mRNA start. The YgjG was expressed as a his6-tag fused protein and purified to homogeneity. The protein catalyzed putrescine:2-oxoglutaric acid (2-OG) aminotransferase reaction (PATase, EC 2.6.1.29). The Km values for putrescine and 2-OG were found to be 9.2 mM and 19.0 mM, respectively. The recombinant enzyme also was able to transaminate cadaverine and, in lower extent, spermidine, and gave maximum activity at pH 9.0. Conclusion Expression of E. coli K12 ygjG coding region revealed σ54-depended ORF which encodes a 459-amino acid protein with putrescine:2-OG aminotransferase activity. The enzyme also was able to transaminate cadaverine and, in lower extent, spermidine.

Abstract: The yicM gene of Escherichia coli was found by selection for resistance to 6-mercaptopurine. Translation and transcription initiation sites of yicM were determined. Overexpression of yicM increased resistance of sensitive cells to inosine and guanosine, decreased E. coli growth rate in medium containing these ribonucleosides as the sole carbon source, led to inosine accumulation by the E. coli strain deficient in purine nucleoside phosphorylase and enhanced the rate of inosine excretion by an inosine-producing strain. These results suggest that yicM encodes a purine ribonucleoside exporter and we have accordingly renamed it nepI (for ‘nucleoside efflux permease – inosine’). [Copyright &y& Elsevier]

Background: Putrescine is the intermediate product of arginine decarboxylase pathway in Escherichia coli which can be used as an alternative nitrogen source. Transaminase and dehydrogenase enzymes seem to be implicated in the degradative pathway of putrescine, in which this compound is converted into γ-aminobutyrate. But genes coding for these enzymes have not been identified so far. Results: The 1.8-kbp DNA fragment containing E. coli K12 ygjG gene with aer-ygjG intergenic region was examined. It was found that the fragment contains σ54-depended open reading frame (ORF) of 1,380 nucleotides encoding a 459-amino acid polypeptide of approximately 49.6 kDa. The cytidine (C) residue localized 10 bp downstream of the σ54 promoter sequence was identified as the first mRNA base. The UUG translation initiation codon is situated 36 nucleotides downstream of the mRNA start. The YgjG was expressed as a his6-tag fused protein and purified to homogeneity. The protein catalyzed putrescine:2-oxoglutaric acid (2-OG) aminotransferase reaction (PATase, EC 2.6.1.29). The Km values for putrescine and 2-OG were found to be 9.2 mM and 19.0 mM, respectively. The recombinant enzyme also was able to transaminate cadaverine and, in lower extent, spermidine, and gave maximum activity at pH 9.0. Conclusion: Expression of E. coli K12 ygjG coding region revealed σ54-depended ORF which encodes a 459-amino acid protein with putrescine:2-OG aminotransferase activity. The enzyme also was able to transaminate cadaverine and, in lower extent, spermidine. [ABSTRACT FROM AUTHOR]

The crude aqueous ethanol extract of the cones of Alnus glutinosa (L.) Gaertn. (Betulaceae; black alder, European alder) was obtained and further partitioned between water and various organic phases. The active water and butanol phases were subjected to assay-guided (DPPH) fractionation using repetitive RP HPLC until individual compounds were isolated. Their antioxidative activities, measured as SC₅₀ values, were evaluated. The chemical structures of the isolated compounds were elucidated with the help of mass spectroscopy, (1)H NMR technique, UV spectroscopy, and chemical approaches. One novel ellagitannin, glutinoin (2), along with two known compounds, pedunculagin (1) and praecoxin D (3), were isolated and found to contribute to antioxidative activity of the A. glutinosa cones extract. The activities (SC₅₀) of 1-3 were evaluated as 0.95 (1), 1.00 (2) and 1.01 µg mL⁻¹ (3). The scavenging effects of glutinoin (2) and praecoxin D (3) were reported for the first time.