Rosana Chehín

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NADH dehydrogenase-2 (NDH-2) from Escherichia coli is a membrane-bound flavoprotein linked to the respiratory chain. We have previously shown that this enzyme has cupric reductase activity that is involved in hydroperoxide-induced oxidative stress. In this paper we present spectroscopic evidence that NDH-2 contains thiolate-bound Cu(I) with luminescence(More)
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a multifunctional enzyme that has been associated with neurodegenerative diseases. GAPDH colocalizes with α-synuclein in amyloid aggregates in post-mortem tissue of patients with sporadic Parkinson disease and promotes the formation of Lewy body-like inclusions in cell culture. In a previous work, we(More)
How thyroid hormones move across biological or model membranes is a subject of controversy. The passage of the 3,5,3′triiodo l-thyronine and 3,5,3′,5′ tetraiodo l-thyronine across model membranes was evaluated by the addition of the hormones to liposomes containing 2,4,6-trinitrobenzene sulfonic acid. Results indicate that hormones can react with an(More)
The effect of thyroid hormones on the degree of order or fluidity of dimyristoyl, dipalmitoyl or egg yolk phosphatidyl choline liposomes was evaluated by fluorescence spectroscopy methods. The freedom of molecular motion above the phase transition temperature was decreased, while below the transition, the mobility was actually increased by the incorporation(More)
Kinetic studies of tetrameric recombinant human tyrosine hydroxylase isoform 1 (hTH1) have revealed properties so far not reported for this enzyme. Firstly, with the natural cofactor (6R)-Lerythro-5,6,7, 8-tetrahydrobiopterin (H4biopterin) a time-dependent change (burst) in enzyme activity was observed, with a half-time of about 20 s for the kinetic(More)
We have studied the conformation and thermal stability of recombinant human phenylalanine hydroxylase (hPAH) and selected truncated forms, corresponding to distinct functional domains, by infrared spectroscopy. The secondary structure of wild-type hPAH was estimated to be 48% alpha-helix, 28% extended structures, 12% beta-turns and 12% non-structured(More)
Two-dimensional infrared spectroscopy has been used to characterize rat liver methionine adenosyltransferase and the events taking place during its thermal unfolding. Secondary structure data have been obtained for the native recombinant enzyme by fitting the amide I band of infrared spectra. Thermal denaturation studies allow the identification of events(More)
Microcin J25 (MccJ25) is a 21 amino acid lasso-peptide antibiotic produced by Escherichia coli and composed of an 8-residues ring and a terminal 'tail' passing through the ring. We have previously reported two cellular targets for this antibiotic, bacterial RNA polymerase and the membrane respiratory chain, and shown that Tyr9 is essential for the effect on(More)
The stability of a lentil lectin, an all-beta protein, has been perturbed by changes in pH and temperature. In the pH interval 5.0 --> 10.0, the overall secondary structure does not undergo significant changes. However, if the individual components of the infrared amide I band are considered, changes in band components attributed to variations in beta-sheet(More)
Lactocin 705 is a bacteriocin whose activity depends upon the complementation of two peptides, termed Lac705alpha and Lac705beta. Neither Lac705alpha nor Lac705beta displayed bacteriocin activity by itself when the growth of sensitive cells was monitored. To obtain molecular insights into the lactocin 705 mechanism of action, Fourier transform infrared(More)