The 2-5A system is one of the major pathways for antiviral and antitumor functions that can be induced by interferons (IFNs). The 2-5A system is modulated by 5-triphosphorylated, 2,5-phosphodiester-linked oligoadenylates (2-5A), which are synthesized by 2,5-oligoadenylate synthetases (2,5-OASs), inactivated by 5-phosphatase and completely degraded by 2-phosphodiesterase (2-PDE). Generated 2-5A activates 2-5A-dependent endoribonuclease, RNase L, which induces RNA degradation in cells and finally apoptosis. Although 2,5-OASs and RNase L have been molecularly cloned and studied well, the identification of 2-PDE has remained elusive. Here, we describe the first identification of 2-PDE, the third key enzyme of the 2-5A system. We found a putative 2-PDE band on SDS-PAGE by successive six-step chromatographies from ammonium sulfate precipitates of bovine liver and identified a partial amino acid sequence of the human 2-PDE by mass spectrometry. Based on the full-length sequence of the human 2-PDE obtained by in silico expressed sequence tag assembly, the gene was cloned by reverse transcription-PCR. The recombinant human 2-PDE expressed in mammalian cells certainly cleaved the 2,5-phosphodiester bond of 2-5A trimer and 2-5A analogs. Because no sequences with high homology to this human 2-PDE were found, the human 2-PDE was considered to be a unique enzyme without isoform. Suppression of 2-PDE by a small interfering RNA and a 2-PDE inhibitor resulted in significant reduction of viral replication, whereas overexpression of 2-PDE protected cells from IFN-induced antiproliferative activity. These observations identify 2-PDE as a key regulator of the 2-5A system and as a potential novel target for antiviral and antitumor treatments.

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Thiomarinol, an antimicrobial antibiotic, was isolated from the culture broth of a marine bacterium, Alteromonas rava sp. nov. SANK73390. Its structure was deduced as a hybrid composed of a pseudomonic acid analogue and holothin by NMRspectral analysis and chemical degradation. Antimicrobial activity against Gram-positive and Gram-negative bacteria of thiomarinol was stronger than both of pseudomonic acids and pyrrothine antibiotics.

The three-dimensional structure of recombinant desulfatohirudin in aqueous solution was determined by 1H nuclear magnetic resonance at 600 MHz and distance geometry calculations with the program DISMAN. The input for the structure calculations was prepared on the basis of complete sequence-specific resonance assignments at pH 4.5 and 22 degrees C and consisted of 425 distance constraints from nuclear Overhauser enhancements and 159 supplementary constraints from spin-spin coupling constants and from the identification of intramolecular hydrogen bonds. Residues 3-30 and 37-48 form a molecular core with two antiparallel beta-sheets and several well-defined turns. The three disulfide bonds 6-14, 16-28, and 22-39 were identified by NMR. In contrast to this well-defined molecular core, with an average root mean square distance for the polypeptide backbone of 0.8 A for a group of nine DISMAN solutions, no preferred conformation was found for the C-terminal segment 49-65, and a loop consisting of residues 31-36 is not uniquely constrained by the NMR data either. These structural properties of recombinant desulfatohirudin coincide closely with the previously described solution conformation of natural hirudin, but the presence of localized differences is indicated by chemical shift differences for residues Asp 5, Ser 9, Leu 15, Asp 53, Gly 54, and Asp 55.

During the course of screening for inhibitors of trehalase, we found the pseudodisaccharide termed trehazolin1 (1) in a culture broth of Micromonospora, strain SANK 62390n. This paper describes the isolation, structure determination, and inhibitory activity of trehazolin. One loopful of the producing organism was aseptically transferred from an agar slant into baffled 500-ml Erlenmeyer flasks each containing 80ml of a primary seed medium.This mediumwas composed of glucose 1%, glycerol 1%, oatmeal 0.5%, sucrose 1%, soybean meal 2%, Casamino acids 0.5%, pressed yeast 1%, CaCO3 0.1%, and Disfoam CB-442 (Nippon Yushi Co.) 0.01%. After formulation, the pH was adjusted to 7.0 with aq NaOH, and the mediumwas sterilized. The incubation was performed on a rotary shaker at 220rpmat 28°C for 216 hours. Forty ml of the primary seed culture were aseptically transferred into baffled 2-liter Erlenmeyer flasks each containing 800ml of a secondary seed/production medium which was composed of glucose 2%, soluble starch 1 %, pressed yeast 0.9%, meat extract 0.5%, Polypepton 0.5%, NaCl 0.5%, CaCO3 0.3%, and Disfoam CB-442 0.01%. The medium was then adjusted to pH 7.2

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The structure of a novel herbicide, hydantocidin isolated from the fermentation broth of Streptomyces hygroscopics SANK 63584, was determined by the combined analysis of MS and 'H NMR spectra. Hydantocidin is a novel spiro compound containing a subofuranoid ring, at the anomeric position of which a hydantoin ring is used such that the C ( 1 ) -N ( l ) linkage is p. The relative configuration and the conformation in solution was determined by quantitative analysis of the NOE spectra and T, values. In CD30D and [2H,]DMS0 (dimethyl sulphoxide) solutions, the ribofuranose moiety of hydantocidin was found to be fixed in a C,-endo conformation, probably due to the rigidity of the spiro structure and hydrogen bonding between 3-OH and the carbonyl group at C-4'.