New 3 (4 hydroxybenzyl)piperazine 2,5 dione, together with the known N [2 (4 hydroxy phenyl)ethyl]acetamide (N acetyltyramine), was isolated for the first time from the marine actinobacterium Streptomyces sp. The chemical structures of these compounds were deter mined by NMR spectroscopy and mass spectrometry. The cytotoxic activities of the com pounds were estimated from their effects on sperm and eggs of the sea urchin Strongylocentrotus intermedius.
The encoding sequence of the pore-forming OmpF-like protein from the Yersinia pseudotuberculosis outer membrane was cloned and expressed in Escherichia coli cells. Conditions were selected for isolation and refolding of recombinant monomer and porin trimer. Their spatial structures were characterized by the intrinsic protein fluorescence and CD spectroscopy. It was shown that the recombinant porins are similar in the composition of secondary structure elements to the isolated porins, but have a considerably less compact tertiary structure. The pore-forming activities of the recombinant proteins are similar to those of Y. pseudotuberculosis native porins. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2008, vol. 34, no. 2; see also http://www.maik.ru.
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