Manuel Soriano-García

Detection and characterization by circular dichroism of a stable intermediate state formed in the thermal unfolding of papain

The thermal unfolding of papain was studied at pH 2.6 by means of circular dichroism and difference spectroscopy. The transition curves obtained from ellipticity changes at 208 and 220 nm were biphasic, i.e., they showed two distinct successive steps, demonstrating the existence of an intermediate state of stable secondary conformation in the denaturation process. Difference-spectroscopy studies indicated that considerable exposure of aromatic side-chains is involved in both steps of the transition. Since papain has two domains in its molecular structure, our results suggest that they unfold in a successive way and rather independently. Furthermore, the structural characteristics of the intermediate state, obtained from its circular dichroism spectrum in the far-ultraviolet region, seem to point out that the second domain (residues 111-212) is the most stable part of the molecule.

Neo-clerodane-type diterpenoids from Salvia keerlii

Abstract From the aerial parts of Salvia keerlii two new neo-clerodane diterpenoids have been isolated. Their structures: 8,12( R )epoxyneo-cleroda-3,13(14)-diene-18,19:15,16-diolide, kerlin and 7-acetoxy-12( R )hydroxyneoclerodane-3,13(14)-diene-18,19:15,16-diolide, kerlinolide, have been established by spectroscopic means. X-ray diffraction analysis was performed for kerlin.

Turbidity as a useful optical parameter to predict protein crystallization by dynamic light scattering

Abstract The aggregation behavior of several proteins in solution including the human apolipoproteins A-II and C-III, as well as concanavalin A, thaumatin, lysozyme and mexicain, is discussed based on dynamic light scattering techniques. According to our results, the estimation of parameters such as the geometrical factor ( H ) and turbidity ( τ ) under different environmental conditions, is a useful approach in order to elucidate if protein aggregation is carried out by either nucleation or random mechanisms. We conclude that dynamic light scattering, an accurate and non-destructive technique, can be used to determine either protein precrystallization parameters or crystallization conditions when both H and τ are taken into account.

Structure of salvigenolide, a novel diterpenoid with a rearranged neo-clerodane skeleton from salviafulgens

Abstract From the aerial parts of Salvia fulgens Cav. (Labiatae) a new diterpenoid with a rearranged neo-clerodane skeleton was isolated. This novel compound named salvigenolide, showed a six-seven A/B ring system with a trans fussion. A probable biogenetic route is proposed. Its structure and relative stereochemistry as in 1 , were established by spectroscopic means and X-ray diffraction analysis.

Synthesis and molecular structure of prolame, N-(3-hydroxy-1,3,5(10)-estratrien-17β-yl)-3-hydroxypropylamine; an amino-estrogen with prolonged anticoagulant and brief estrogenic effects

The synthesis and molecular structure of prolame, N-(3-hydroxy-1,3,5(10)-estratrien-17 beta-yl)-3-hydroxypropylamine, is described. It was characterized by ir, nmr, mass spectrometry and chemical analysis. The crystal structure of this compound was determined by single-crystal x-ray diffraction. Prolame belongs to space group P212121. Cell dimensions are: a = 8.356(2), b = 13.343(4) and c = 16.119(4) A. Z = 4; R = 4.1%.

Crystallization of hevein; A protein from latex of Hevea brasiliensis (Rubber Tree)

Abstract Large single crystals of hevein, a low molecular weight protein from the latex of the rubber tree, have been grown with 2-methyl,2–4 pentanediol, as a first step for an X-ray diffraction study.

Amino acid sequence, biochemical characterization, and comparative modeling of a nonspecific lipid transfer protein from Amaranthus hypochondriacus

Plant nonspecific lipid transfer proteins (nsLTPs) are characterized by their ability to bind a broad range of hydrophobic ligands in vitro. Their biological function has not yet been elucidated, but they could play a major role in plant defense to physical and biological stress. An nsLTP was isolated from Amaranthus hypochondriacus seeds and purified by gel filtration and reversed-phase high-performance liquid chromatography techniques. The molecular mass of the protein as determined by mass spectrometry is 9747.29 Da. Data from amino acid sequence, circular dichroism and binding/displacement of a fluorescent lipid revealed that it belongs to the nsLTP1 family. The protein shows the alpha-helical secondary structure typical for plant nsLTPs 1 and shares 40 to 57% sequence identity with nsLTPs 1 from other plant species and 100% identity with an nsLTP1 from Amaranthus caudatus. A model structure of the protein in complex with stearate based on known structures of maize and rice nsLTPs 1 suggests a protein fold complexed with lipids closely related to that of maize nsLTP1.

Abietane type diterpenoids from Salvia fruticulosa. A revision of the structure of fruticulin B

Abstract The structures of fruticulin A and its free phenol derivative, highly oxidized diterpene quinones isolated from Salvia fruticulosa, were determined by spectroscopic methods, chemical transformations and X-ray crystallographic analysis of one of them. The structure of fruticulin B is revised to a linear arrangement as a result of an X-ray diffraction analysis.

The anticoagulant effect of prolame, N-(3-hydroxy-1,3,5(10) estratrien-17β-yl)-3-hydroxypropylamine, a novel amino-estrogen

The anticoagulant and estrogenic effects of prolame, N-(3-hydroxy-1,3,5(10)-estratrien-17 beta-yl)-3-hydroxypropylamine, are described. A single subcutaneous injection of prolame in male mice, ovariectomized mice, adult and infant male rats, produced dose-dependent increases of blood clotting time, which could be observed with the larger doses even after 4 days. In ovariectomized mice, prolame produced vaginal cornifications of shorter duration than those produced by estradiol-17 beta. The evidence suggests that, in contrast with currently used estrogens, prolame would not generate cardiovascular accidents if used for the treatment of prostatic carcinoma; it could also be exceptionally effective for the prevention of thrombosis.

Stability of the C-terminal peptide of CETP mediated through an (i, i+4) array

Based on circular dichroism (CD), we have found an essential (i, i + 4) alpha-helix stabilizing array in the C-terminus region for the cholesteryl ester transfer protein (CETP) between histidine 466 and aspartic acid 470. This region apparently corresponds to an amphipathic alpha-helix. The behavior of this peptide in solution in comparison with a mutant peptide (D470N) was also analyzed by dynamic light scattering (DLS). The results showed that alpha-helix stabilization is not due to peptide aggregation. The thermodynamic estimation of stability supports the idea that the phenomenon is carried out through an (i, i + 4) array. The representation of the C-terminal region as an amphipathic alpha-helical peptide shows that lipid-binding activity might be in part due to both the asymmetric polar/non-polar residue distribution and to the presence of an (i, i + 4) array important for helix stability.