A zone phenomenon and a progressive reaction occurring with a radioactive hemolysin,sodium erucate,I 131

Sodium erucate reacts progressively (i.e., once the reaction is started in a time which is so short that the lysin is in contact with the red cells for 30 seconds, it cannot be stopped even by being diluted 10-fold) with human red cells at pH 7. At the same time, systems containing the lysin and human red cells show a zone phenomenon, lysis occurring most readily in a certain concentration of lysin but more slowly in larger or smaller concentrations. Sodium erucate-I¹³¹ can be used to investigate both the zone phenomenon and the progressive character of the reaction. As regards the former, large concentrations of the lysin react relatively poorly with the red cell surfaces and the resistance of the red cells is relatively high. This may be due to the presence of an admixed inhibitor or to the development of an inhibitory state. The lysin is taken up and fixed by material in the red cell surface, so that the "internal phase" of lysin attached to the cell surfaces is so firmly fixed that a 10-fold dilution has no effect on it. It follows that lysis in these systems is progressive, as it is found to be.     

Isolation and Structure of a New Steroid,Asterosapogenine I,from Asterosaponins A and B

A new steroid, asterosapogenine I, was isolated as the main component in acid hydrolyzates of asterosaponins A and B. The structure of the compound was assigned to be 3,β,6α-dihydroxy-5α-pregn-9(11)-en-20-one.     

A New Insertion Variant, IS231I, Isolated from a Mosquito-Specific Strain of Bacillus thuringiensis

A new insertion variant belonging to the family IS231, designated IS231I, was isolated from a mosquito larvicidal strain of the Bacillus thuringiensis serovar sotto (H4ab). IS231I was 1653 bp long and delimited by two 20 bp inverted repeats with one mismatch, flanked by two perfect 11 bp direct repeats. The element contained a single open reading frame (ORF) encoding 478 amino acids and five conserved domains: N1, N2, N3, C1, and C2. The 5′ noncoding region upstream of the ORF, presumed to form a stable stem-and-loop structure, was highly conserved in IS231I. The secondary structure conformation had a deduced free energy (ΔG = 25°C) of −17.2 kcal/mol. Comparison of the IS231I amino acid sequence with those of the 10 existing IS variants revealed that the new variant shares 89% identity with IS231A and IS231B, 65–66% with IS231M and IS231N, and 38% with IS231W.     

Polymerization of pNcollagen I and copolymerization of pNcollagen I with collagen I. A kinetic, thermodynamic, and morphologic study.

Previous observations established that pNcollagen III copolymerized with collagen I and decreased the diameter of the fibrils formed (Romanic, A.M., Adachi, E., Kadler, K.E., Hojima, Y., and Prockop, D.J. (1991) J. Biol. Chem. 266, 12703-12709). Here, procollagen I alone or mixtures of procollagen I and pCcollagen I were incubated with procollagen C-proteinase to generate pNcollagen I or mixtures of pNcollagen I and collagen I. The results confirmed previous reports that pNcollagen I assembles into sheet-like structures. They also demonstrated that polymerization of pNcollagen I exhibits a lag period and propagation phase similar to those seen with other protein self-assembly systems. In addition, the results demonstrated that pNcollagen I formed true copolymers with collagen I in that the presence of pNcollagen I increased the lag time, decreased the propagation rate, and increased the concentration of collagen I in solution at equilibrium. Copolymerization of pNcollagen I with collagen I, however, differed in two features from copolymerization of pNcollagen III with collagen I. One was that, in confirmation of previous work, copolymerization of pNcollagen I with collagen I markedly altered the circularity of the fibrils formed. The second difference was that the copolymerization increased the concentration in solution at equilibrium of pNcollagen I whereas copolymerization with collagen I was previously shown to decrease the concentration in solution of pNcollagen III. The increase in concentration in solution of pNcollagen I was explicable either by the assembly of soluble oligomers of pNcollagen I and collagen I, or by subtle changes in the activities of pNcollagen I and collagen I in the solid-phase. Comparison with previous data with pNcollagen III indicated that although pNcollagen I and pNcollagen III copolymerize with collagen I, there are marked differences in the two kinds of copolymers.     

Crystal structure of a sweet tasting protein thaumatin I, at 1.65 A resolution.

The crystal structure of thaumatin I, a potently sweet protein isolated from the fruits of the West African shrub, Thaumatococcus danielli Benth, has been refined at a resolution better than 1.65 A using a combination of energy minimization and stereochemically restrained least-squares methods. The final model consists of all 207 amino acids, 28 alternate amino acid conformers and 236 waters, with a crystallographic R-factor of 0.145 for 19,877 reflections having F > 4 sigma F between 10.0 A and 1.65 A (R = 0.167 for all 24,022 reflections). The model has good stereochemistry, with root-mean-square deviations from ideal values for bond and angle distances of 0.014 A and 0.029 A, respectively. The estimated root-mean-square co-ordinate error is 0.15 A. The current model confirms the previously reported 3.1 A C alpha trace in both main chain connectivity and disulfide topology, including two disulfide bonds, that differed from the earlier reported biochemical determination. The structure contains three domains. The core of the molecule consists of an eleven-stranded, flattened beta-sandwich folded into two Greek key motifs. All beta-strands in this sandwich are antiparallel except the parallel N-terminal and the C-terminal strands. The average hydrogen bond length in this sandwich is 2.89 A, with an angle of 155.1 degrees. Two beta-bulges are found in one of the sheets. The second domain consists of two beta-strands forming a beta-ribbon and connected by an omega-loop, and contains a proline residue in cis conformation. This structural motif folds back against the main sandwich to form a smaller sandwich-like structure. The third domain is a disulfide-rich region stretching away from the sandwich portion of the molecule. It contains one alpha-helix and three short helical fragments. Two of the helical segments are connected by an unusually sharp turn, stabilized by a disulfide bridge. One of the three disulfide bonds in this domain takes on two conformations.     

A Mesophilic,Autotrophic, Ammonia-Oxidizing Archaeon of Thaumarchaeal Group I.1a Cultivated from a Deep Oligotrophic Soil Horizon

Soil nitrification plays an important role in the reduction of soil fertility and in nitrate enrichment of groundwater. Various ammonia-oxidizing archaea (AOA) are considered to be members of the pool of ammonia-oxidizing microorganisms in soil. This study reports the discovery of a chemolithoautotrophic ammonia oxidizer that belongs to a distinct clade of nonmarine thaumarchaeal group I.1a, which is widespread in terrestrial environments. The archaeal strain MY2 was cultivated from a deep oligotrophic soil horizon. The similarity of the 16S rRNA gene sequence of strain MY2 to those of other cultivated group I.1a thaumarchaeota members, i.e., Nitrosopumilus maritimus and “Candidatus Nitrosoarchaeum koreensis,” is 92.9% for both species. Extensive growth assays showed that strain MY2 is chemolithoautotrophic, mesophilic (optimum temperature, 30°C), and neutrophilic (optimum pH, 7 to 7.5). The accumulation of nitrite above 1 mM inhibited ammonia oxidation, while ammonia oxidation itself was not inhibited in the presence of up to 5 mM ammonia. The genome size of strain MY2 was 1.76 Mb, similar to those of N. maritimus and “Ca. Nitrosoarchaeum koreensis,” and the repertoire of genes required for ammonia oxidation and carbon fixation in thaumarchaeal group I.1a was conserved. A high level of representation of conserved orthologous genes for signal transduction and motility in the noncore genome might be implicated in niche adaptation by strain MY2. On the basis of phenotypic, phylogenetic, and genomic characteristics, we propose the name “Candidatus Nitrosotenuis chungbukensis” for the ammonia-oxidizing archaeal strain MY2.     

Evidence that the intermediate electron acceptor,A2, in Photosystem I is a bound iron-sulfur protein

Absorption changes accompanying the formation of light-induced P-700⁺ were investigated in a highly enriched Photosystem I preparation where an intermediate electron acceptor preceding P-430 could be detected. In an enriched Photosystem I particle, light-induced reversible absorption changes observed at 700 nm in the presence of dithionite resembled those previously seen at 703 nm and 820 nm [9], thus indicating the presence of a backreaction between P-700⁺ and A^?₂. After this same Photosystem I particle was treated to denature the bound iron-sulfur centers, the photochemical changes that could be attributed to P-700 A₂ were completely lost. These results provide evidence that the intermediate electron acceptor, A₂, is a bound iron-sulfur protein. Additional studies in the 400–500 nm region with Photosystem I particles prepared by sonication indicate that the spectrum of A₂ is different from that of P-430.     

Piceatannol,a natural trans-stilbene compound,inhibits human glyoxalase I

Human glyoxalase I (GLO I), a rate-limiting enzyme for detoxification of methylglyoxal (MG), a by-product of glycolysis, is known to be a potential therapeutic target for cancer. Here, we searched new scaffolds from natural compounds for designing novel GLO I inhibitors and found trans-stilbene scaffold. We examined the inhibitory abilities to human GLO I of commercially available trans-stilbene compounds. Among them, piceatannol was found to have the most potent inhibitory activity against human GLO I. Piceatannol could inhibit the proliferation of human lung cancer NCI-H522 cells, which are dependent on GLO I for survival, in a dose- and time-dependent manner. In addition, piceatannol more significantly inhibited the proliferation of NCI-H522 cells than that of NCI-H460 cells, which are less dependent on GLO I. Importantly, overexpression of GLO I in NCI-H522 cells resulted in less sensitive to the antiproliferative activity of piceatannol. Taken together, this is the first report demonstrating that piceatannol inhibits GLO I activity and the GLO I-dependent proliferation of cancer cells. Furthermore, we determined a pharmacophore for novel inhibitors of human GLO I by computational simulation analyses of the binding mode of piceatannol to the enzyme hot spot in the active site. We suggest that piceatannol is a possible lead compound for the development of novel GLO I inhibitory anticancer drugs.     

A new antitumor antibiotic, chounghwamycin A. I. Taxonomy, isolation and characterization

Chounghwamycin A, a new antitumor antibiotic produced by a strain of Streptomyces sp. No. PL-D-5, was isolated and characterized. It appeared to belong to the actinomycin group of antibiotics from physico-chemical studies and has an empirical formula of C63H88N11O21. The antibiotic is extractable into an organic solvent from the fermentation broth, possessing potent antileukemic activity against P388 mouse leukemia in mice and antimicrobial activity against Gram-positive bacteria with MIC values about 0.1-0.4 microgram/ml, but showed no activity on Gram-negative bacteria, yeast and fungi tested.     

I Shop, Therefore I Am

The Shopping Experience. Pasi Folk and Colin Campbell eds. London: Sage, 1997. 212 pp.
. Theory of Shopping. Daniel Miller. Ithaca, NY: Cornell University Press, 1998. 180 pp.
Shopping, Place and Identity. Daniel Miller. Peter Jackson. Nigel Thrift. Beverly Holbrook. and Michael Rowlands. London: Routledge, 1998. 214 pp.     

Absolute stereochemistry of acremolactone A, a novel herbicidal epoxydihydropyranyl gamma-lactone from Acremonium roseum I4267

Acremolactone A was chemically degraded to the bicyclic hemiacetal gamma-lactone and an epoxycyclohexenol, and their stereochemistry was determined by spectroscopic methods. These observations and data from NOE experiments on acremolactone A led to the configurational assignment of all asymmetric carbons in acremolactone A, enabling its stereostructure to be established.     

Modo-UG, a marsupial nonclassical MHC class I locus

Modo-UG is a class I gene located in the MHC of the marsupial Monodelphis domestica, the gray, short-tailed opossum. Modo-UG is expressed as three alternatively spliced mRNA forms, all of which encode a transmembrane form with a short cytoplasmic tail that lacks phosphorylation sites typically found in classical class I molecules. The three alternative mRNAs would encode a full-length form, an isoform lacking the α2 domain, and one lacking both α2 and α3 domains. Genotyping both captive-bred and wild M. domestica from different geographic regions revealed no variation in the residues that make up Modo-UG’s peptide-binding groove. Modo-UG’s low polymorphism is contrasting to that of a nearby class I locus, Modo-UA1, which has a highly polymorphic peptide-binding region. Absence of functional polymorphism in Modo-UG is therefore not a general feature of opossum class I genes but the result of negative selection. Modo-UG is the first MHC linked marsupial class I to be described that appears to clearly have nonclassical features.Electronic Supplementary Material Supplementary material is available for this article at