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At least 829 records · Page 46Linked to original sources
PubMed2002

Fluorescence studies of pyrene maleimide-labeled translin: excimer fluorescence indicates subunits associate in a tail-to-tail configuration to form octamer.

Translin is an octameric single-stranded DNA binding protein consisting of 228 amino acid residues per monomer. This protein contains two cysteine residues per monomer. Studies of reactions with DTNB show that both cysteines are reactive and exhibit biphasic reaction kinetics. Further studies with two site-directed mutants, C58S and C225S, confirm that Cys-58 reacts slowly while Cys-225 reacts quickly. Pyrene excimer emission was observed for pyrene maleimide-labeled C58S mutant. This was not observed, however, with the pyrene maleimide-labeled C225S mutant. DAS (decay associated spectra) revealed that all excited pyrene labels on C225 residues can form excimers with pyrenes of adjacent subunits within a few nanoseconds. Time-resolved emission anisotropy detects a rotational correlation time appropriate for octameric but not dimeric species. These results indicate proximity for the Cys-225 residues on adjacent monomers and that the subunits must interact in a tail-to-tail orientation. Moreover, disulfide bonds are not required for the formation of an octamer.

Base Sequence↗
PubMed1989

Multiple labelling of immunoglobulin G, albumin and testosterone with a fluorescent terbium chelate for fluorescence immunoassays.

Human immunoglobulin G, human serum albumin and testosterone were labelled with the 4-aminosalicylic acid derivative of diethylenetriaminepentaacetic acid complexed with terbium ions. An exceptionally large amount of label, of the order of a few hundred moles of complex per mole of analyte, could be conjugated to the compounds tested by the use of poly-L-lysine. Self-quenching appears to be minimal, even with this high local concentration of fluorophores. The tracers were stable at 4 degrees C, and gave competitive calibration graphs at physiological concentrations.

Chelating Agents↗
PubMed1993

Do photobleached fluorescent microtubules move?: re-evaluation of fluorescence laser photobleaching both in vitro and in growing Xenopus axon.

We previously documented differences in the behavior of microtubules in growing axons of two types of neurons, adult mouse sensory neurons and Xenopus embryonal spinal cord neurons. Namely, the bulk of microtubules was stationary in mouse sensory neurons both by the method of photoactivation of caged-fluorescein-labeled tubulin and photobleaching of fluorescein-labeled tubulin, but the bulk of microtubules did translocate anterogradely by the method of photoactivation. Although these results indicated that the stationary nature of photobleached microtubules in mouse neurons is not an artifact derived from the high levels of energy required for the procedure, it has not yet been settled whether the photobleaching method can detect the movement of microtubules properly. Here we report photobleaching experiments on growing axons of Xenopus embryonal neurons. Anterograde movement of photobleached microtubules was observed at a frequency and translocation rate similar to the values determined by the method of photoactivation. Our results suggest that, under appropriate conditions, the photobleaching method is able to reveal the behavior of microtubules as accurately as the photoactivation method.

Animals↗
PubMed1993

Detection of the outer membrane lipoprotein I and its gene in fluorescent and non-fluorescent pseudomonads: implications for taxonomy and diagnosis.

The open reading frame of the OprI lipoprotein gene from Pseudomonas aeruginosa was amplified by polymerase chain reaction (PCR) starting from purified DNA or colony lysates. A fragment of the expected size (249 bp) was detected in all P. aeruginosa strains from various clinical and geographical origins. The gene could only be amplified in pseudomonads of rRNA group I which are considered to be the authentic genus Pseudomonas. Digestions with HaeIII, PvuII and SphI of the amplified fragments demonstrated a sequence variation in the oprI gene. Colony, dot and Western blots with two monoclonal antibodies (mAbs) against the lipoprotein I confirmed our PCR results. These findings open interesting perspectives for the molecular taxonomy of the genus Pseudomonas and the development of diagnostic tools.

Antibodies, Monoclonal↗