The influence of amino acid sequence and structural context on the backbone dynamics of EF-hand calcium-binding loops was investigated using 15N spin relaxation measurements on the calcium-free state of the calbindin D(9k) mutant (A14D+A15Δ+P20Δ+N21G+P43M), in which the N-terminal pseudo- EF-hand loop, characteristic of S100 proteins, was engineered so as to conform with the C-terminal consensus E

Calcium activation of the C-terminal domain of calmodulin was studied using 1H and 15N NMR spectroscopy. The important role played by the conserved bidentate glutmate Ca2+ ligand in the binding loops is emphasized by the striking effects resulting from a mutation of this glutantic acid to a glutamine, i.e. E104Q in loop III and E140Q in loop IV. The study involves determination of Ca2+ binding con

The homodimeric S100 protein calcyclin has been studied in the apo state by two-dimensional 1H NMR spectroscopy. Using a combination of scalar correlation and NOE experiments, sequence-specific 1H NMR assignments were obtained for all but one backbone and >90% of the side-chain resonances. To our knowledge, the 2 x 90 residue (20 kDa) calcyclin dimer is the largest protein system for which such co

Calbindin D9k exhibits cooperative binding of two calcium ions, hence study of the half-saturated states of the protein is critical to understanding the binding process. However, the half-saturated states are not significantly populated under equilibrium conditions. To circumvent this problem, an absolutely conserved glutamic acid residue in the C-terminal binding site (site II) has been mutated t

Counterion 23Na spin relaxation data are reported from the microemulsion phase in the AOT/water/isooctane system as a function of the water/AOT ratio, which determines the size of the aqueous droplets. The 23Na NMR measurements comprise three independent relaxation rates, allowing the individual spectral density values to be determined, as well as the second-order quadrupolar dynamic shift. The ef

Water 17O longitudinal and transverse relaxation rates have been measured in aqueous solutions and mesophases of the non-ionic alkyl oligo(ethylene oxide) surfactants C12En (n = 4, 5, 8) over wide ranges of temperature and concentration. In addition, two reference systems have been investigated: high molecular weight poly(ethylene oxide) and the dimer 1,2-dimethoxy ethane. The relaxation data are

A 2H n.m.r. relaxation study of sodium dodecyl sulphate (SDS) in the micellar phase is presented. The surfactant is specifically deuterated in the α-, γ- and ω-positions. Relaxation data are obtained at two temperatures and at three field strengths, and show a dependence on the field strength. The data are analysed with the 'two-step' model of relaxation, and the fast correlation times as well as

A frequency-dependent 14N and 13C NMR relaxation study of the micellar region formed by a very long zwitterionic surfactant, viz., 6-(dimethyleicosylammonio)hexanoate (C20AH), is presented. As a starting point the binary phase diagram of C20AH/D2O is determined. The phase diagram is similar to those found for shorter chain ionic surfactants with bulky head groups. The NMR relaxation data show a de

Publisher Summary This chapter discusses the current status, of using nuclear magnetic resonance (NMR), to study the structure and dynamics of the holliday junction (HJ). Complex deoxyribonucleic acid (DNA) structures (e.g., triplexes, quadruplexes, junctions) pose difficult problems for study, by NMR, relative to the typical DNA duplexes, because they have nonstandard or distorted local conformat

Background: Coagulation activation is a hallmark of cancer, and anticoagulants have shown tumour-inhibiting properties. However, recent trials have failed to demonstrate improved survival with low-molecular-weight heparin (LMWH) in cancer populations. This has raised the question of suboptimal adherence as a possible explanation for the lack of benefit. Still, there is no standardised method to di

Melanoma is a highly metastatic cancer, and its incidence has increased over the past several decades. Angiogenesis is associated with melanoma metastasis and a poor prognosis. Many genetic and epigenetic factors affecting tumour vascularization and metastasis have been investigated, despite the heterogeneity of cancer cells and the complicated mechanisms involved in melanoma. Nemo-like kinase (NL