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Biomedical subjects

M Charlier

Publications and source records attributed to M Charlier.

At least 91 records · Page 5Linked to original sources
PubMed1977

Circular dichroism studies of the binding of o-nitrophenyl-beta-D-fucoside and o-nitrophenyl-beta-D-galactoside to lac repressor.

The binding of o-nitrophenyl-beta-D-fucoside and o-nitrophenyl-beta-D-galactoside to Escherichia coli lac repressor was investigated by circular dichroism in the wavelength range 300--400 nm corresponding to the o-nitrophenyl chromophores. The CD signal of both ligands drastically changed when they bound to lac repressor due to the asymmetric interaction of the o-nitrophenyl ring with chemical groups of protein. The CD spectra of bound ligands indicate close similarity between the environment of o-nitrophenyl-beta-D-fucoside and o-nitrophenyl-beta-D-galactoside on lac repressor. The CD signal is used to calculate the binding parameters (K and n) to lac repressor. It is demonstrated that the limited proteolytic digestion of lac repressor which gives a 'core protein' does not affect the environment of both ligands on the protein.

Bacterial Proteins↗
PubMed1976

Functional relationships between myotatic reflex arcs of the lower limb in man: investigation by excitability curves.

In 30 normal subjects, the influence of the reflex activation of one myotatic reflex arc on the excitability of other myotatic reflex arcs of the lower limb has been investigated using excitability curves. Soleus, quadriceps, and short biceps tendon reflexes as well as H reflex at two different intensities (liminal and H max/2) were used either as conditioning or as conditioned responses. The reflex activation of the soleus muscle has opposite effects on antagonistic muscle groups of the thigh: facilitation of the quadriceps myotatic arc and inhibition of the short biceps myotatic reflex arc. Conversely, activation of both quadriceps and short biceps muscles leads to a marked and long lasting (+/- 5000 ms) inhibition of the soleus myotatic reflex arc. The differences of functional organization between proximal and distal myotatic reflex arcs are emphasized and the role of the afferent impulses secondary to the conditioning muscular contraction is discussed.

Afferent Pathways↗
PubMed1974

Specific recognition of single-stranded regions in ultraviolet-irradiated and heat-denatured DNA by tryptophan-containing peptides.

Fluorescence studies of the binding of peptides containing lysyl and tryptophyl residues to nucleic acids show that two types of complexes are formed. One of them involves a direct interaction of the tryptophyl ring with nucleic acid bases, which leads to fluorescence quenching. Comparison with proton magnetic resonance and circular dichroism data indicates that this fluorescence quenching is due to a stacking of the indole ring with bases. Quantitative analysis of fluorescence data leads to the conclusion that stacking is favored in single-stranded regions of DNAs, which are produced either by heating or by UV-irradiation of the native DNA sample. The binding of the peptide Lys-Trp-Lys is about ten times tighter in these single-stranded regions as compared with double-stranded ones. A short tripeptide such as Lys-Trp-Lys is, therefore, able to discriminate between single-stranded and double-stranded regions. Moreover, bound peptide molecules photosensitize the splitting of thymine dimers in UV-irradiated DNA, thus providing a model for DNA photoreactivation.

Binding Sites↗