Antigenic diversity of cytochromes c3 from the anaerobic,sulfate-reducing bacteria,Desulfovibrio

An indirect enzyme-linked immunoadsorption assay (ELISA) was developed for cytochrome c₃ using antisera to the cytochromes fromDesulfovibrio africanus Benghazi, Desulfovibrio vulgaris Hildenborough andDesulfovibrio salexigens British Guiana. The ELISA system was used to test for cross-reactions between these antisera and the heterologous antigens. In contrast to previous experiments using the Ouchterlony technique, all of the cytochromes c₃ tested exhibited some degree of cross-reaction. Considerable variation was seen in cross-reactions for cytochromes c₃ from differing strains ofD. desulfuricans. This observation raises questions about the taxonomic relatedness of these strains. No cross-reaction was seen with eukaryotic cytochrome c or withD. vulgaris cytochrome c₅₅₃. The data demonstrate that cytochrome c₃ is capable of undergoing nonprecipitating cross-reactions, and thus may not be as immunologically unique as was once thought.Abbreviations ELISA Enzyme-linked immunoadsorption assay     

Is multicomponent spectra analysis coming to a deadlock?

We have emphasized the information which can be expected from complex absorption spectra analysis in the range of linear algebra.We have considered the different methods now used and examined the conditions in which this information can be effectively available from spectra analysis. When all composite spectra are known the most accurate method to extract the expected information is to use experimental reference spectra and to compute their contributions in the analysed complex form.When all composite spectra are unknown it is basically impossible to reach the solution from the only knowledge of the complex absorbance values.To remove this indetermination requires additional indications like the existence of non-overlapping areas, or additional relations involving the absorbance values like the relation between redox potential and absorbance in the case of oxidation reduction couples.Although our study is presented on a biological background, we have borne in mind the generality of this problem.     

Acetyl coenzyme A biosynthesis in the chloroplast

Acetyl coenzyme A (CoA) biosynthesis in spinach chloroplasts has been investigated by following the incorporation of bicarbonate and acetate into fatty acids under a variety of conditions. Both substrates were readily incorporated into fatty acids in a light-dependent manner by intact photosynthesising chloroplasts, but when the concentrations of these substrates were adjusted to those found in vivo, i.e. 200 M acetate, 10 M bicarbonate, then acetate was found to supply carbon atoms for fatty acids biosynthesis via acetyl CoA at forty times the rate of bicarbonate. It is proposed that extra-chloroplastic free acetate is the pricipal substrate for chloroplasts acetyl CoA biosynthesis in spinach.Abbreviations ACP acyl carrierprotein - CoASH coenzyme A     

Chemical carcinogenesis by the two-stage protocol in the skin ofMastomys natalensis (Muridae) using topical initiation with 7,12-dimethylbenz(a)anthracene and topical promotion with 12-0-tetradecanoylphorbol-13-acetate

Virchows Archiv B Cell Pathology - The long-term (34 weeks) topical administration of 7,12-dimethylbenz(a)anthracene (DMBA) to the skin of male and femaleMastomys induced a broad spectrum of benign...     

Proteolytic modification of mouse liver catalase

When catalase was immunoprecipitated from different subfractions of mouse liver homogenates, the enzyme which was obtained from extracts of the large granular fraction exhibited a lower molecular weight than that from either the cytosol or purified peroxisomal fractions, as judged by sodium dodecyl sulphate polyacrylamide gel electrophoresis. This modification of the enzyme could be prevented by the addition of proteolytic inhibitors to extraction buffers; and consequently, unmodified catalase was able to be purified in the presence of 5 mM iodoacetamide. Electrophoretic comparison of the catalases against standards of known molecular sizes indicated that the unmodified enzyme had a subunit mass approximately 2,000 daltons larger than the modified enzyme. The significance of these proteolytic modifications has been discussed in relation to the involvements of catalase and peroxisome turnover.     

A polymorphic variant of human erythrocyte carbonic anhydrase I with a widespread distribution in Australian aborigines,CAIAustralia-9 (8 Asp → Gly): Purification,properties, amino acid substitution,and possible physiological significance of the variant enzyme

Carbonic anhydrase I (EC 4.2.1.1) purified from the pooled packed red blood cells of 100 individuals typed as heterozygous for the common Australian Aboriginal carbonic anhydrase I variant CAI Australia-9 had a slightly higher specific CO2 hydratase or esterase (toward p-nitrophenyl acetate) activity than the normal component and a higher Km and Vmax using the esterase substrate. The variant enzyme was slightly more resistant to heat inactivation. The extent of inhibition of both enzymes by the specific inhibitor acetazolamide was identical, as was their immunological behavior and the lability of the active-site zinc ion. The variant enzyme was more resistant to chloride inhibition. The physiological importance of this observation is discussed in the context of a proposed adaptive advantage of the variant gene in the arid western and central regions of Australia. The amino acid substitution in the Aboriginal variant of a glycine for an aspartic acid residue has been located at residue 8 from the N terminus (i.e., 8 Asp leads to Gly), by proteolytic and partial acid hydrolyses. The possible effects of this substitution on the structure and function of the molecule are discussed.     

Neisseria gonorrhoeae prepilin export studied in Escherichia coli.

The pilE gene of Neisseria gonorrhoeae MS11 and a series of pilE-phoA gene fusions were expressed in Escherichia coli. The PhoA hybrid proteins were shown to be located in the membrane fraction of the cells, and the prepilin product of the pilE gene was shown to be located exclusively in the cytoplasmic membrane. Analysis of the prepilin-PhoA hybrids showed that the first 20 residues of prepilin can function as an efficient export (signal) sequence. This segment of prepilin includes an unbroken sequence of 8 hydrophobic or neutral residues that form the N-terminal half of a 16-residue hydrophobic region of prepilin. Neither prepilin nor the prepilin-PhoA hybrids were processed by E. coli leader peptidase despite the presence of two consensus cleavage sites for this enzyme just after this hydrophobic region. Comparisons of the specific molecular activities of the four prepilin-PhoA hybrids and analysis of their susceptibility to proteolysis by trypsin and proteinase K in spheroplasts allow us to propose two models for the topology of prepilin in the E. coli cytoplasmic membrane. The bulk of the evidence supports the simplest of the two models, in which prepilin is anchored in the membrane solely by the N-terminal hydrophobic domain, with the extreme N terminus facing the cytoplasm and the longer C terminus facing the periplasm.     

Phylogenetic relationships within the class Oligohymenophorea,phylum Cilophora,inferred from the complete small subunit rRNA gene sequences ofColpidium campylum,Glaucoma chattoni,andOpisthonecta henneguyi

Summary Phylogenetic relationships within the class Oligohymenophorea, phylum Ciliophora, were investigated by determining the complete small subunit rRNA (SSrRNA) gene sequences for the hymenostomesColpidium campylum, Glaucoma chattoni, and the peritrichOpisthonecta henneguyi. The affiliations of the oligohymenophoreans were assessed using both distance matrix (DM) and maximum parsimony (MP) analyses. Variations do exist in the phylogenies created by the two methods. However, the basic tree topologies are consistent. In both the DM and MP analyses the hymenostomes (C. campylum, G. chattoni, and the tetrahymenas) all form a very tight group associated with the peritrichO. henneguyi. TheTetrahymena lineage was monophyletic whereasColpidium andGlaucoma were more closely related to each other than either was to the tetrahymenas. The monophyly of the genusTetrahymena in the present analysis supports the phylogenies determined from morphological data and molecular sequence data from the histone H3II/H4II region of the genome. The perplexing and controversial phylogenetic position of the peritrichs is once again depicted in the present analysis. The distinctiveness of the peritrichOpisthonecta from both hymenostome and nassophorean ciliates based on evolutionary distances suggests that the elevation of the peritrichs to a higher taxonomic rank should be reconsidered.