Search results for " secondary"

Lunasin is a redox sensitive intrinsically disordered peptide with two transiently populated α-helical regions.

2016

Lunasin is a 43 amino acid peptide with anti-cancer, antioxidant, anti-inflammatory and cholesterol-lowering properties. Although the mechanism of action of lunasin has been characterized to some extent, its exact three-dimensional structure as well as the function of the N-terminal sequence remains unknown. We established a novel method for the production of recombinant lunasin that allows efficient isotope labeling for NMR studies. Initial studies showed that lunasin can exist in a reduced or oxidized state with an intramolecular disulfide bond depending on solution conditions. The structure of both forms of the peptide at pH 3.5 and 6.5 was characterized by CD spectroscopy and multidimen…

In vivo selection of heterotypically interacting transmembrane helices: Complementary helix surfaces, rather than conserved interaction motifs, drive…

2017

Single pass transmembrane proteins make up almost half of the whole transmembrane proteome. Contacts between such bitopic transmembrane proteins are common, and oligomerization of their single transmembrane helix is involved in triggering and regulation of signal transduction across cell membranes. In several recent analyses the distribution of amino acids at helix-helix contact sides has been analyzed, and e.g. a preference of amino acids with small side chains has been identified. Here we select amino acids, amino acid pairings and amino acid motifs, which mediate strong interactions of single-span transmembrane α-helices. Our analysis illustrates an architecture of TM helix dimers that i…

Extraordinary stability of hemocyanins from L. polyphemus and E. californicum studied using infrared spectroscopy from 294 to 20 K

2016

International audience; Hemocyanins are large oligomeric respiratory proteins found in many arthropods and molluscs. Here we give infrared spectroscopic evidence of a high stability towards exposure to sub-zero temperatures for hemocyanins from the arthropods Limulus polyphemus and Eurypelma californicum at different pH values. Small but distinct temperature induced changes of the secondary structure were observed, but a stable core of at least 40% α-helical structure is preserved as identified in the infrared spectra obtained between 294 and 20 K. The structural changes differ in detail somewhat for the two hemocyanins, with overall fewer changes observed in the case of E. californicum. No…

Protein-protein interactions can be predicted using coiled coil co-evolution patterns

2016

AbstractProtein-protein interactions are sometimes mediated by coiled coil structures. The evolutionary conservation of interacting orthologs in different species, along with the presence or absence of coiled coils in them, may help in the prediction of interacting pairs. Here, we illustrate how the presence of coiled coils in a protein can be exploited as a potential indicator for its interaction with another protein with coiled coils. The prediction capability of our strategy improves when restricting our dataset to highly reliable, known protein-protein interactions. Our study of the co-evolution of coiled coils demonstrates that pairs of interacting proteins can be distinguished from no…

Multi-approach metabolomics analysis and artificial simplified phytocomplexes reveal cultivar-dependent synergy between polyphenols and ascorbic acid…

2017

Fruits of the sweet cherry (Prunus avium L.) accumulate a range of antioxidants that can help to prevent cardiovascular disease, inflammation and cancer. We tested the in vitro antioxidant activity of 18 sweet cherry cultivars collected from 12 farms in the protected geographical indication region of Marostica (Vicenza, Italy) during two growing seasons. Multiple targeted and untargeted metabolomics approaches (NMR, LC-MS, HPLC-DAD, HPLC-UV) as well as artificial simplified phytocomplexes representing the cultivars Sandra Tardiva, Sandra and Grace Star were then used to determine whether the total antioxidant activity reflected the additive effects of each compound or resulted from synergis…

Chemical messages from an ancient buried bottle: Metabolomics for wine archeochemistry.

2017

Restoration works in the old Clunisian Saint-Vivant monastery in Burgundy revealed an unidentified wine bottle (SV1) dating between 1772 and 1860. Chemical evidence for SV1 origin and nature are presented here using non-targeted Fourier Transform Ion Cyclotron Resonance Mass Spectrometry and Nuclear Magnetic Resonance analyses. The SV1 chemical diversity was compared to red wines (Pinot Noir) from the Romanée Saint Vivant appellation and from six different vintages spanning from 1915 to 2009. The close metabolomic signature between SV1 and Romanée Saint Vivant wines spoke in favor of a filiation between these wines, in particular considering the Pinot noir grape variety. A further statistic…

Structural and mechanistic insights into the interaction of the circadian transcription factor BMAL1 with the KIX domain of the CREB-binding protein

2019

JBC papers in press xx, 16604-16619 (2019). doi:10.1074/jbc.RA119.009845

Glycometabolic Alterations in Secondary Adrenal Insufficiency: Does Replacement Therapy Play a Role?

2018

Secondary adrenal insufficiency (SAI) is a potentially life-threatening endocrine disorder due to an impairment of corticotropin (ACTH) secretion from any process affecting the hypothalamus or pituitary gland. ACTH deficit can be isolated or associated with other pituitary failures (hypopituitarism). An increased mortality due to cardiovascular, metabolic, and infectious diseases has been described in both primary and secondary adrenal insufficiency. However, few studies have provided compelling evidences on the underlying mechanism in SAI, because of the heterogeneity of the condition. Recently, some studies suggested that inappropriate glucocorticoid (GCs) replacement therapy, as for dose…

Application of FTIR Spectroscopy to Analyze RNA Structure

2020

Fourier transform infrared (FTIR) spectroscopy has been widely used for the analysis of both protein and nucleic acid secondary structure. This is one of the vibration spectroscopy methods that are extremely sensitive to any change in molecular structure. While numerous reports describe how to proceed to analyze protein and deoxyribonucleic acid (DNA) structures using FTIR, reports related to the analyses of ribonucleic acids (RNAs) are few. Nevertheless, RNAs are versatile molecules involved in a multitude of roles in the cell. In this chapter, we present applications of FTIR for the structural analysis of RNA, including the analysis of helical parameters and noncanonical base pairing, oft…

2019

Mammalian fetuin-A and fetuin-B are abundant serum proteins with pleiotropic functions. Fetuin-B is a highly selective and potent inhibitor of metallopeptidases (MPs) of the astacin family, which includes ovastacin in mammals. By inhibiting ovastacin, fetuin-B is essential for female fertility. The crystal structure of fetuin-B was determined unbound and in complex with archetypal astacin, and it was found that the inhibitor has tandem cystatin-type modules (CY1 and CY2). They are connected by an exposed linker with a rigid, disulfide-linked `CPDCP-trunk', and are followed by a C-terminal region (CTR) with little regular secondary structure. The CPDCP-trunk and a hairpin of CY2 form a bipar…