Rodolfo R. Biekofsky

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Examination of the NMR 15N chemical shifts of a number of EF-hand proteins shows that the shift value for the amido nitrogen of the residue in position 8 of a canonical EF-hand loop (or position 10 of a pseudo EF-hand loop) provides a good indication of metal occupation of that site. The NH of the residue in position 8 is covalently bonded to the carbonyl(More)
Pineal hormone melatonin (N-acetyl-5-methoxytryptamine) is thought to modulate the calcium/calmodulin signaling pathway either by changing intracellular Ca(2+) concentration via activation of its G-protein-coupled membrane receptors, or through a direct interaction with calmodulin (CaM). The present work studies the direct interaction of melatonin with(More)
The fold of calmodulin (CaM) consists of two globular domains connected by a helical segment (the linker), whose conformational properties play a crucial role for the protein's molecular recognition processes. Here we investigate the structural properties of the linker by performing a 11.5 ns molecular dynamics (MD) simulation of calcium-loaded human CaM in(More)
EF-hands are Ca(2+) binding motifs that are widely distributed throughout the entire living organism kingdom. At present, relatively little is known at a quantum mechanical level about the mechanisms that allow Ca(2+) to be recognized specifically by EF-hands and to induce a conformational switch from a compact ("closed") conformation to an "open" state(More)
Fragile X syndrome (FXS) is the most common form of inherited intellectual disability. Previous studies have implicated mGlu5 in the pathogenesis of the disease, and many agents that target the underlying pathophysiology of FXS have focused on mGluR5 modulation. In the present work, a novel pharmacological approach for FXS is investigated. NNZ-2566, a(More)
Ca4.calmodulin (Ca4.CaM) inhibits the glycolytic enzyme phosphofructokinase, by preventing formation of its active tetramer. Fluorescence titrations show that the affinity of complex formation of Ca4.CaM with the key 21-residue target peptide increases 1000-fold from pH 9.0 to 4.8, suggesting the involvement of histidine and carboxylic acid residues. 1H NMR(More)
This work shows that the partial replacement of diamagnetic Ca2+ by paramagnetic Tb3+ in Ca2+/calmodulin systems in solution allows the measurement of interdomain NMR pseudocontact shifts and leads to magnetic alignment of the molecule such that significant residual dipolar couplings can be measured. Both these parameters can be used to provide structural(More)
This study focuses on a closed net of electron-pair donor-acceptor interactions, present in the core of all metal-bound EF-hand pairs, that link both metal ions across a short two-stranded beta-sheet. A molecular model based on the above cycle of interactions was studied using semi-empirical molecular orbital quantum mechanical methods. The calculations(More)
A general method is presented for magnetic field alignment of proteins in solution. By tagging a target protein with calmodulin saturated with paramagnetic lanthanide ions it is possible to measure substantial residual dipolar couplings (RDC) whilst minimising the effects of pseudocontact shifts on the target protein. A construct was made consisting of a(More)
Alzheimer's disease (AD) is the most common cause of dementia, affecting more than 36 million people worldwide. Octodon degus, a South American rodent, has been found to spontaneously develop neuropathological signs of AD, including amyloid-β (Aβ) and tau deposits, as well as a decline in cognition with age. Firstly, the present work introduces a novel(More)