XANES study of iron displacement in the haem of myoglobin

The XANES (X‐ray absorption near edge structure) spectra of deoxy human adult haemoglobin (HbA) and myoglobin (Mb) have been measured at the wiggler beam line of the Frascati synchrotron radiation facility. The XANES are interpreted by the multiple scattering cluster theory. The variations in the XANES between HbA and Mb are assigned to changes in the Fe‐porphyrin geometry

Transposons played a major role in the diversification between the closely related almond and peach genomes: Results from the almond genome sequence

We sequenced the genome of the highly heterozygous almond Prunus dulcis cv. Texas combining short and long‐read sequencing. We obtained a genome assembly totaling 227.6 Mb of the estimated 238 Mb almond genome size, of which 91% is anchored to eight pseudomolecules corresponding to its haploid chromosome complement, and annotated 27,969 protein‐coding genes and 6,747 non‐coding transcripts. By phylogenomic comparison with the genomes of 16 additional close and distant species we estimated that almond and peach (P. persica) diverged around 5.88 Mya. These two genomes are highly syntenic and show a high degree of sequence conservation (20 nucleotide substitutions/kb). However, they also exhibit a high number of presence/absence variants, many attributable to the movement of transposable elements (TEs). TEs have generated an important number of presence/absence variants between almond and peach, and we show that the recent history of TE movement seems markedly different between them. TEs may also be at the origin of important phenotypic differences between both species, and in particular, for the sweet kernel phenotype, a key agronomic and domestication character for almond. Here we show that in sweet almond cultivars, highly methylated TE insertions surround a gene involved in the biosynthesis of amygdalin, whose reduced expression has been correlated with the sweet almond phenotype. Altogether, our results suggest a key role of TEs in the recent history and diversification of almond and its close relative peach.info:eu-repo/semantics/publishedVersio

Synchrotron radiation small angle x-ray scattering studies of protein aggregation

Parm

Molecular dynamics of microperoxidases in aqueous and nonaqueous solutions

We report an extended molecular dynamics study of the heme-containing peptide ''microperoxidase'' (MP), a model system of several heme-proteins. The most commonly studied forms of MP, the octa- and the undecapeptide, are studied both in pure water conditions and in mixed solvent (80% methanol and 20% water) conditions that stabilize the monomeric form. The equilibrium structures and their stability are visualized by graphical tools and analyzed in terms of the molecular shape, the vibrational amplitudes, and torsional angles along the backbone. The obtained structures are used to confirm the experimental data on aggregation of Urry and Pettegrew(7.8) by using simple geometric arguments based on the possible assemblies of several monomeric units in space. We have investigated in detail the H-bond network and the influence on the heme conformational properties. We have found that heme interacts with the peptide through H-bonds formed by the propionates, the axial histidine, and different partners of the peptidic chain. These interactions are regulated by the degree of exposure of HIS to the solvent. These results permit us to predict that the undecapeptide and the octapeptide can be good model systems for horseradish peroxidase and cytochrome c', respectively

Influence of glycerol on the structure and stability of ferric horse heart myoglobin: A SAXS and circular dichroism study

The influence of glycerol on the structural properties of Fe(III)-horse heart myoglobin has been investigated by absorbance, CD and SR-SAXS spectroscopy. The results obtained indicate that both the tertiary and the secondary (alpha-helix) conformations of the protein are influenced by glycerol; in particular, an increase of approx. 8% in helical content was observed. Further, analysis of both the acid- and guanidine-induced denaturation transitions points to a glycerol-induced decreased stability of the tertiary structure; conversely, the alpha-helix conformation is found to be stabilized by the organic solvent. Finally, the SR-SAXS data show that gyration radius, cross-section and thickness of the protein increase in the presence of the organic solvent; however, the protein maintains a compact state