PubMed Health⌕ Search

Biomedical subjects

F F de Mul

Publications and source records attributed to F F de Mul.

25 records · Page 2Linked to original sources
PubMed1988

Resonance Raman spectroscopy of complexes of the helix destabilizing proteins GP32 and GP5 with poly(rA) and poly(dA).

The bacteriophage T4 helix destabilizing protein (hdp) gp32 and its complexes with poly(rA) and poly(dA) were studied with ultra-violet resonant Raman spectroscopy. The UV-resonant Raman (UV-RR) spectrum of the complex of gp5, the coat protein of bacteriophage M13, with poly(dA) was also measured and is compared with the spectrum of the gp 32/poly(dA) complex. The excitation wavelength was 245.1 nm. This is on the far UV-side of the first absorption bands of adenine and near a "window" in the protein absorption spectrum. The overlap of fluorescence due to chromophores present in the protein and resonance Raman scattering was prevented by this choice of wavelength. The spectra of the protein/polynucleotide complexes are compared with the native nucleotide spectra measured at varying temperatures. The hyperchromicity which is expected when a nucleotide changes from a stacked to an unstacked conformation was not observed for poly(rA), neither upon temperature increase nor on protein binding. In both cases poly(dA) revealed a clear hyperchromicity. This different behavior of poly(rA) and poly(dA) is probably a consequence of their different conformations. The contributions of the proteins to the spectra is weak except for two bands, at 1550 and 1610 cm-1 due to tryptophan (in case of gp32) and one band near 1610 cm-1 due to tyrosine and phenylalanine.

Chemical Phenomena↗
PubMed1988

Forehead skin blood flow in normal neonates during active and quiet sleep, measured with a diode laser Doppler instrument.

Changes in forehead skin blood flow during active and quiet sleep were determined in 16 healthy neonates using a recently developed semi-conductor laser Doppler flow meter with-out light conducting fibres. Measurements were carried out at a postnatal age varying from 5 hours to 7 days. The two sleep states could be distinguished in 17 recordings. The mean skin blood flow values during active sleep were significantly higher (p less than 0.01) than those during quiet sleep, the mean increase being 28.1%. The variability of the flow signal, expressed as the coefficient of variation, changed significantly from 23.1% during active sleep to 18.2% during quiet sleep.

Forehead↗
PubMed1987

A Raman scattering study of the helix-destabilizing gene-5 protein with adenine-containing nucleotides.

Raman spectra of gp5 and complexes of gp5 with poly(rA) and poly(dA) have been determined and analysed. From a fit of the amide I-band with model spectra it follows that the secondary structure of gp5 contains 52% beta-sheet, 28% undefined conformation and 19% alpha-helix. The band at 1032 cm-1 due to phenylalanine has an anomalous intensity both in the spectra of the complexes and the free protein. This possibly indicates a stacked structure present in the protein. Binding of gp5 to poly(rA) and poly(dA) influences the intensity of bands near 1338 and 1480 cm-1 which are considered to be marker-bands for the phosphate-sugar-base conformer. A change in conformation of the nucleotides is also reflected by vibrations originating in the phosphate- and sugar-residues of the backbone. In the spectrum of complexed poly(rA) the intensity of the conformation sensitive band at 813 cm-1, which is due to the phosphodiester group, is zero. It seems that gp5 forces poly(rA) and poly(dA) to a similar conformation. A marker band for stacking interaction in poly(rA) indicates that stacking interactions in the complex have increased.

Coliphages↗
PubMed1986

Micro-Raman line broadening in synthetic carbonated hydroxyapatite.

Using a Raman microspectrometer, we have recorded Raman spectra of synthetically produced hydroxyapatite samples with varying carbonate contents. The apatites were produced from aqueous solutions at about 40 degrees C. From line-broadening values of the symmetric phosphate stretch, it was concluded that the carbonate substitution in these lattices has a maximum of 4.5 wt %. Both phosphate and hydroxyl ions seem to be involved in the carbonate substitution process.

Carbonates↗
PubMed1984

Raman microspectroscopy in human pathology.

Microscopic inclusions due to inhaled particles in human tissue sections were identified in situ by Raman microspectroscopy. Different types of substances, including talc, rutile, alpha-quartz, calcite, and related compounds, were traced. In addition, the nature of pulmonary "blue bodies" was studied.

Adult↗