Purification and primary structure of C-1027-AG, a selective antagonist of antitumor antibiotic C-1027, from Streptomyces globisporus.

C-1027-AG, a selective antagonist of antitumor antibiotic C-1027, was isolated by column chromatography on DEAE-cellulose, butyl-Toyopearl and Sephadex G-50 from a culture filtrate of Streptomyces globisporus. The amino acid sequence of purified C-1027-AG was determined with a protein sequencer on the basis of fragment peptides obtained by enzymatic hydrolysis with lysylendopeptidase, V8 protease, endopeptidase AspN and chymotrypsin, after performic acid oxidation. C-1027-AG is shown to consist of a single polypeptide chain cross-linked by two disulfide bonds, and to contain a total of 110 amino acid residues with alanine and glycine as its amino- and carboxyl-termini, respectively; its molecular weight was calculated to be 10,500 daltons. The primary structure of C-1027-AG is indicated to be identical to the protein moiety of C-1027, and is highly homologous to the sequences of antitumor proteins obtained from other Streptomyces species.

The origin of the DNA induced circular dichroism of CC-1065 and analogs.

The calf thymus DNA (CT-DNA) and poly(dI-dC).poly(dI-dC) binding properties of the natural antitumor antibiotic CC-1065 and selected analogs of CC-1065 were studied by circular dichroism (CD) and absorbance methods. The results indicate that the intense long wavelength DNA-induced CD band of these molecules originates from a chiral electronic transition which is delocalized over the whole molecule. Both the covalently bound species (N-3 adenine adduct) and the reversibly bound species exhibit the characteristic spectral behavior of an inherently dissymmetric chromophore when these agents bind within the minor groove of B-form DNA. This mechanism of optical activity accounts for why CC-1065 shows a weak CD in buffer but a very intense induced CD at long wavelength when bound to DNA, why the intensity of the induced CD of CC-1065 analogs depends upon how many fused ring systems the analog contains, and why covalently bound analogs having the mirror image configuration of the natural configuration also exhibit an intense positive induced CD band at long wavelength.

Artritis de rodilla por Streptomyces Somaliensis: un caso / Arthritis of knee for streptomyces somaliensis: a case

Se presenta un caso de artritis de rodilla por Streptomyces somaliensis, raro agente causal de micetomas, que predomina en el continente africano. Es el segundo caso encontrado en la Argentina, con aislamiento e identificación microbiológica del agente causal y el único donde se demostró compromiso intra-articular

Three-dimensional structure of an alpha-amylase inhibitor HAIM as determined by nuclear magnetic resonance methods.

The three-dimensional structure of an alpha-amylase inhibitor, HAIM, composed of 78 amino acids, was analyzed by two-dimensional NMR techniques. Sequence-specific assignments were made for the amino acid residues from Ile-6 to Cys-72. Distance geometry analysis of the interresidue NOEs revealed that the HAIM molecule consists of two beta-sheets, as is the case in a homologous alpha-amylase inhibitor, Tendamistat, though one of its beta-strands is much shorter than that of Tendamistat. The combination of molecular modeling from Tendamistat and distance geometry analysis was confirmed to be useful for our purpose.

DNA strand scission by the novel antitumor antibiotic leinamycin.

Leinamycin is a recently discovered antitumor antibiotic with an unusual 1,3-dioxo-1,2-dithiolane structure. It preferentially inhibits the incorporation of [3H]thymidine into the acid-insoluble fraction of Bacillus subtilis. In vitro, leinamycin causes single-strand cleavage of supercoiled double-helical pBR322 DNA in the presence of thiol cofactors. Scavengers of oxygen radical did not supress the DNA-cleaving activity. Thiol-activated leinamycin binds calf thymus DNA at 4 degrees C and thermal treatment of the leinamycin-DNA adduct released a chemically modified leinamycin from the complex. The lack of cytotoxicity and DNA-cleaving activity for S-deoxyleinamycin indicates that the 1,3-dioxo-1,2-dithiolane moiety is essential for the activity of leinamycin. Thus, the primary cellular target of leinamycin appears to be DNA. It binds DNA and causes single-strand break at low concentrations, which may account for the potent antitumor activity.

Proton NMR studies of apo-neocarzinostatin from Streptomyces carzinostaticus. Sequence-specific assignment and secondary structure.

The sequence-specific resonance assignment of apo-neocarzinostatin from Streptomyces carzinostaticus was carried out from two-dimensional proton-NMR spectra. The assignments were obtained for the backbone protons of 111 of the 113 residues of the protein, missing the two C alpha H of one glycine but including 3 of the 4 prolines. The majority of side chain protons were also assigned. The secondary structure derived from the analysis of sequential connections corresponds to ten beta-strands separated by clearly identified loops and turns. Inter-strand connectivities and slowly exchanging amide protons confirm the presence of the two disulfide bridges from Cys37 to Cys47 and from Cys88 to Cys93 and indicate a global folding similar to that of the similar proteins, actinoxanthin and macromomycin, for which crystallographic data are available.

Resorthiomycin, a novel antitumor antibiotic. I. Taxonomy, isolation and biological activity.

Resorthiomycin, a novel antitumor antibiotic, was isolated from the fermentation broth of a strain of Streptomyces collinus by ethyl acetate extraction, silica gel chromatography and HPLC. Resorthiomycin exhibited an in vitro cytotoxic activity against mouse leukemia L5178Y cells (IC50, 15.5 micrograms/ml) and also inhibited the clonogenic activity of a multidrug-resistant mutant of human hepatoma PLC/PRF/5 cells to a greater extent than that of the parental cells. On the other hand, this antibiotic does not possess any antibacterial or antifungal activity.

Leinamycin, a new antitumor antibiotic from Streptomyces: producing organism, fermentation and isolation.

Leinamycin (DC 107) is newly discovered antitumor antibiotic with an unusual 1,3-dioxo-1,2-dithiolane structure. Five different producing strains were isolated from soils collected in Japan during 1985-1988 and were taxonomically assigned as Streptomyces. Fermentation studies indicate: Leinamycin was unstable in culture broth. A chemically defined medium could be designed for a preferable production. Streptomyces sp. S-140 grew on medium supplemented with Zn2+ and high porus polymer resin and accumulated 32 micrograms/ml of leinamycin. Improved isolation methods are described along with identification of mikamycin A co-produced with leinamycin by the strain S-140.

A structurally unique, potent, and selective oxytocin antagonist derived from Streptomyces silvensis.

The in vitro and in vivo oxytocin/arginine vasopressin (OT/AVP) antagonist properties of two cyclic hexapeptides derived from a newly discovered natural product (L-156,373) of Streptomyces silvensis are described. In radioligand binding assays, L-156,373 [cyclo(L-Pro-D-Phe-N-OH-L-Ile-D-piperazyl-L-piperazyl-N-Me-D -Phe)] exhibited moderate affinity for rat uterine OT receptors (Ki, 150 nM), with some selectivity (approximately 20-fold) vs. liver AVP-V1 and kidney AVP-V2 receptors. Dehydroxylation of N-hydroxyisoleucine and oxidation of the piperazic acid residues of L-156-373 produced an interesting derivative, L-365,209. These structural modifications increased OT receptor affinity and selectivity by 20- and 2.5-5-fold, respectively. In the isolated rat uterus, L-365,209 was a potent (apparent dissociation constant, 1.7 nM) and competitive OT antagonist. L-365,209 also blocked the effects of AVP at both AVP-V1 (phosphatidylinositol turnover in rat hepatocytes) and AVP-V2 (adenylate cyclase in rat kidney medulla) receptors, but only at low micromolar concentrations. L-365,209, given iv to anesthetized rats, antagonized the action of exogenous OT on the uterus (ID50, 460 micrograms/kg) with a relatively long duration of action. L-365,209 represents a unique class of compounds that provides an entirely new approach for the design of antagonists for these neurohypophyseal hormones.

1H-nmr analysis of herbimycins and dihydro-herbimycins.

Herbimycin A [1] and herbimycin C [3] and their dihydro-derivatives 5 and 6, respectively, have been obtained from the cell broth of Streptomyces hygroscopicus, and the assignment of their 1H-nmr has been completed. Strong cytotoxic activity of antibiotics 1, 3, 5, and 6 against the P-388 and KB lymphocytic leukemia test systems has been demonstrated.

The structures of new antifungal antibiotics, benanomicins A and B.

Structures of new antifungal antibiotics, benanomicins A and B were determined to be N-[[5-[6-deoxy-3-O-(beta-D-xylopyranosyl)-beta-D-galactopyranosyloxy+ ++ ]-5, 6-dihydro-1,6,9,14-tetrahydroxy-11-methoxy-3-methyl-8,13-dioxobenzo++ + [a]naphthacen-2-yl]carbonyl]-D-alanine and N-[[5-[4-amino-4,6-dideoxy-3-O-(beta-D-xylopyranosyl)-beta-D- galactopyranosyloxy]-5,6-dihydro-1,6,9,14-tetrahydroxy-11-methoxy- 3-methyl-8,13-dioxobenzo[a]naphthacen-2-yl]carbonyl]-D-al ani ne, respectively, by spectral analyses and chemical degradation studies.

A new pyrrole-amidine antibiotic TAN-868 A.

A new pyrrole-amidine antibiotic TAN-868 A was isolated from the culture broth of Streptomyces idiomorphus sp. nov. Its chemical structure was determined by spectroscopic analyses and degradation studies to be 4-[(2S,4R)-4-hydroxy-5-iminoprolyl]amino- N-(2-amidinoethenyl)-2-pyrrolecarboxamide. The antibiotic is active against bacteria, fungi and a protozoan, and has cytotoxic activity against murine tumor cells. DNA thermal denaturation studies suggest that TAN-868 A preferentially interacts with AT rich regions of double-stranded DNA.