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C Cocito

Publications and source records attributed to C Cocito.

At least 91 records · Page 5Linked to original sources
PubMed1983

Comparison of the cytoplasmic antigens of leprosy-derived corynebacteria and some mycobacteria.

The immunological relationship between leprosy-derived corynebacteria (LDC) and reference mycobacteria was analysed by crossed immunoelectrophoresis with intermediate gel. For this purpose, three reference systems (LDC15/anti-LDC15, LDC18/anti-LDC8, and LDC8/anti-LDC8) were developed. They showed 15 to 20 distinct antigenic components in LDC cytoplasm. Extensive cross-reactivity was observed among different LDC isolates, affecting 3 to 17 components. Moreover, several components were shown to cross-react with mycobacteria when anti-bacillus Calmette-Guérin (BCG), anti-Mycobacterium leprae, other antisera and lepromatous leprosy sera were incorporated in the intermediate gel. The major cross-reactive component, antigen M, was present in all LDC isolates and cross-reacted with antigen 7 of M. leprae and antigen 60 of M. bovis BCG. The thermostability of these antigens and the specificity of the cross-reacting antigens were assessed. The data underline the degree of immunochemical homogeneity within the LDC group of micro-organisms and relatedness with M. leprae and other mycobacteria.

Corynebacterium↗
PubMed1982

Analysis of mycolic acids from a group of corynebacteria by capillary gas chromatography and mass spectrometry.

The cell wall of leprosy-derived corynebacteria (a group of 'diphtheroids' isolated from human leprosy lesions and patients' blood) was previously shown to contain, in addition to peptidoglycan and arabinogalactan, mycolic acids. These alpha-branched beta-hydroxy fatty acids were attributed to the corynomycolic group, according to their RF in monodimensional thin-layer chromatography. In the present work, mycolic acids from leprosy-derived and reference corynebacteria have been fractionated by monodimensional and bidimensional thin-layer chromatography and by gas chromatography. Pyrolyzed mycolic acids have been analyzed on conventional packed columns, whereas intact methyl esters of mycolic acids with free and silylated beta-hydroxyl group have been analyzed on capillary columns, and their structure has been established by mass spectrometry. In all leprosy-derived corynebacteria, some 20 components containing 24-36 carbon atoms and 0-4 double bonds were obtained. The three major groups had 32, 34 and 36 carbons, and the frequency of unsaturated versus saturated chains increased proportionally to the molecular weight. For comparison, the main components of a reference corynebacterium. Corynebacterium diphtheriae PW8, had 30 and 32 carbons, and their hydrocarbon chains were essentially saturated. This work confirms the relative chemical homogeneity of different leprosy-derived corynebacteria and describes some peculiar traits in the chemical structure of this group of organisms. In addition, it shows the complexity of the mycolic acid fraction of corynebacterial cell wall and suggests that the mycolic acid pattern is a sort of fingerprint of each bacterial strain grown under standard conditions. Finally, the fractionation of intact corynomycolic acid methyl esters with free or silylated beta-hydroxyl group by capillary gas chromatography proved to be the best analytical procedure at present available for resolving this complex mixture of corynomycolate isomers. Structural determination of silylated samples by mass spectrometry is preferred because they have more diagnostic fragments.

Cell Wall↗
PubMed1981

Competition between erythromycin and virginiamycin for in vitro binding to the large ribosomal subunit.

When the S component of virginiamycin binds in vitro to the 50 S ribosomal subunit, a change of fluorescence intensity proportional to the amount of complex formed occurs. Erythromycin competes with virginiamycin S for attachment to ribosomes, and removes previously bound virginiamycin S from its target, as revealed by spectrofluorimetric analysis. The 50 S subunits which are incubated with the M component of virginiamycin (50 S*) have an increased affinity for virginiamycin S (the association constants of virginiamycin S with ribosomes are 2.5 x 10(6) M-1 in the absence of virginiamycin M, and 15 x 10(6) M-1 in its presence). Erythromycin does not compete with virginiamycin S for attachment to 50 S* subunits nor is it able to remove virginiamycin S previously bound to the 50 S* subunit. Thus, virginiamycin M produces a change in ribosomes, which results in a tighter complex virginiamycin S-50 S* subunit. Such change does not require the presence of virginiamycin M, however, as shown by the observation that ribosomes to which labeled virginiamycin M is transiently linked bind virginiamycin S in a form that cannot be removed by erythromycin.

Binding Sites↗
PubMed1981

Primary structure of the wall peptidoglycan of leprosy-derived corynebacteria.

The cell walls isolated from axenically grown leprosy-derived corynebacteria were submitted to various chemical and enzymatic degradations. The glycan strands of the wall peptidoglycan are essentially composed of N-acetylglycosaminyl-N-acetylmuramic acid disaccharide units. Small amounts of N-acetylglycosaminyl-N-glycolylmuramic acid (less than 10%) were also detected. The muramic acid residues of adjacent glycan strands are substituted by amidated tetrapeptide units which, in turn, are cross-linked through direct linkages extending between the C-terminal D-alanine residue of one tetrapeptide and the mesodiaminopimelic acid residue of another tetrapeptide. Such a structure is very similar to that of the wall peptidoglycan found in the taxonomically related microorganisms of the Corynebacterium, Mycobacterium, and Nocardia groups.

Corynebacterium↗
PubMed1981

Chemical identification of some cell-wall components of microorganisms isolated from human leprosy lesions.

The cell walls of 24 coryneform non-acid-fast, Gram-positive organisms isolated from human leprosy lesion, were hydrolysed and analysed. Four known chemical markers of different high polymer components of the walls of microorganisms of the CMN (Corynebacterium, Mycobacterium, Nocardia) group were detected in whole cells and cell wall hydrolysates of the coryneform bacteria analyzed. These markers were: meso-diaminopimelic acid (peptidoglycan), arabinose and galactose (arabinogalactan), and mycolic acids. In addition, mycolic acids proved to be of the corynomycolic type, as shown by thin layer chromatography analysis. The conclusion was drawn that these coryneform strains independently isolated from patients of different countries, represent a homogeneous group within the genus Corynebacterium. This inference is supported by a parallel work showing that the guanine-plus-cytosine content of the DNA of these coryneform strains falls within the range of values characteristic of true corynebacteria pathogenic for animals.

Amino Acids, Diamino↗
PubMed1980

Lasting damage to bacterial ribosomes by reversibly bound virginiamycin M.

The M and S components of virginiamycin (VM and VS) inhibit protein synthesis in bacteria--reversibly when a single component is present and irreversibly when both are present. In cell-free systems, each factor binds to the large ribosomal subunit, and the affinity of ribosomes for VS is enhanced in the presence of VM. The present work shows that the action of VM (a 500-dalton modified depsipeptide) in vivo and in vitro persists upon its removal. The in vivo demonstration is based on the loss of viability of uninfected bacteria, and on the irreversible inactivation of virus-infected cells, that are caused by a sequential incubation with VM and VS (the inhibitory action of either component alone is reversible). In vitro, the binding of labeled VM to ribosomes, followed by its detachment, yields particles unable to perform poly(U)-directed polyphenylalanine synthesis. Also, the association constant for the binding of VS to these particles is equal to that of particles incubated with a mixture of VM and VS. Our findings indicate that VM action is catalytic rather than stoichiometric, and suggest the occurrence of two states of the large ribosomal subunit, a situation leading to a complex equilibrium with multiple transitional steps in the presence of virginiamycin.

Bacillus subtilis↗
PubMed1979

Inhibition of protein synthesis in chloroplasts from plant cells by virginiamycin.

The light-driven incorporation of amino acids by isolated spinach chloroplasts is inhibited by the M component (VM) and not by the S component (VS) of virginiamycin. This inhibitory effect is partially reversible. In chloroplast extracts, poly(U)-directed polyphenylalanine formation is strongly inhibited by VM and not by VS. The in vivo synergistic effect of VM and VS observed in bacteria and algae, does not occur in isolated chloroplasts and chloroplast extracts.

Chloroplasts↗
PubMed1978

A spectrofluorimetric study of the interaction between virginiamycin S and bacterial ribosomes.

Virginiamycin S (VS, a type B component of the synergistin group of antibiotics) is fluorescent in solution: the fluorescence intensity is proportional to VS concentration. The intensity of VS fluorescence was found to increase upon addition of 50S ribosomal subunits, and this variation (deltaI 416 nm) to be proportional to the concentration of 50S subunits. This new technique was, then, used to measure the binding reaction of VS to ribosomes. Similar patterns of linkage were obtained for ribosomes and large subunits, whereas very little fixation to 30S particles was detected. The binding reaction was virtually instantaneous at any temperature, and, for saturating VS, was not influenced by Mg++ concentration in the range 1 to 20 mM, nor by the replacement of 100 mM K+ with NH+4. The association constant of VS TO 50S particles was found to be KA=2.5 X 10(6)M-1, and from the Scatchard plot a v value of 0.9 was calculated, which points to a stoichiometric reaction leading to 1 mole VS bound per mole of 50S particles. Upon fixation of virginiamycin M (VM, a type A component of the synergistin group of antibiotics), the delta I of the VS-ribosome complex was increased, and a KA=15 x 10(6)M-1 was recorded for the association constant of VS to 50S particles. Such sixfold increase in the affinity of ribosomes for VS may account for the synergistic effect of the 2 virginiamycin components in sensitive bacteria.

Binding, Competitive↗