1,720,969 research outputs found
Synthesis, characterization and interaction with DNA of dichlorobiscyclo-(glycil-L-methionyl)platinum(II).
No full textConformational studies on particles of turnip yellow mosaic virus
No full textCircular dichroism studies (CD) of turnip yellow mosaic virus (TYMV) nucleoprotein and of its isolated RNA and capsid revealed that: (i) the nucleic acid structure, which comprises a considerable amount of base pairing and/or stacking, remains essentially unchanged irrespective of whether the RNA is encapsidated or free; (ii) the secondary structure of the protein component is mainly accounted for by β- and irregular forms without appreciable amounts of α-helix; (iii) the interaction of capsid protein and RNA induces some conformational changes in the protein probably involving a decrease of β-structure and a perturbation of the microenvironment of some aromatic residues. The influence of temperature on the CD spectra of virus nucleoprotein, RNA and capsid was also investigated. The results are discussed in connection with particle stability
Synthetic fragments and analogues of elastin. I. The synthesis
No full textThe synthesis of some repetitive sequences of elastin and their simplified analogues, all comprising the structural unit Gly-X-Gly (X = Val, Leu, Ala), is described. In particular, the following peptides and polypeptides were synthesized and characterized: Boc-Gly-Val-Gly-Gly-Leu-OMe, Boc-Gly-Leu-Gly-Gly-Val-OMe, Boc-(Gly-Val-Gly-Gly-Leu)2-OMe, Boc-(Gly-Val-Gly-Gly-Leu)3-OMe, Boc-Gly-Val-Gly-Gly-OEt, Boc-Leu-Gly-Gly-Leu-OMe, Boc-Val-Gly-Gly-Val-OMe, poly(Ala-Gly-Gly), poly(Val-Gly-Gly), and poly (Leu-Gly-Gly).
In every case, the synthesis was accomplished by classical procedures in solution, by using the p-nitrophenyl ester method for the polycondensation step, and the mixed anhydride or the azide methods for the coupling steps
Synthetic fragments and analogues of Elastin. II Conformational studies
No full textConformational studies on synthetic repetitive sequences and analogues of elastin are described. CD and nmr measurements gave evidence of flexible beta-turns as the dominant structural feature whose stability was found to decrease by increasing the number of repetitive units. The sequences comprised the structural unit Gly-X-Gly (X = Val, Leu, Ala), with X-Gly or Gly-Gly located at the corners of the bend. Based on that, it is proposed that these regions of elastin, unlike the proline-containing sequences, contribute to the elasticity of the protein through a classical mechanism in terms of the rotational isomeric state theory
Polypeptide models of elastin: CD and NMR studies on synthetic poly(Ile-Gly-Gly)
No full textPoly(X-Gly-Gly), simple structural models for the hydrophobic, proline-devoid, regions of elastin, have been synthesized and studied by circular dichroism and NMR spectroscopies. The results gave evidence of type II beta-turns as the only ordered structure present in the polymers. The stability of the turns has been shown to decrease on hydration and to increase in the series Leu less than Ala less than Val less than Ile
Potentiometric and NMR studies on Cd2+ coordination with the histidine-containing Ac184-188NH(2) prion protein fragment
No full textTo elucidate the specific mode and site of binding between metal ions and prion protein (PrPc), we synthesized the pentapeptide Ac184–188NH2 (AcIKQHTNH2), corresponding to helical region II of the protein, and its analogous acetylated at the lysine side chain.
The acid–base properties of both peptides and their interaction with Cd2+ were studied in aqueous solution by NMR and potentiometry.
Speciation data were compared with those achieved for Cd2+/4-methylimidazole, taken as the reference system. Both NMR and potentiometric data indicate that Cd2+ is coordinated by the histidine residue. The involvement of the side chain amine of lysine in the metal coordination is excluded by NMR data, whereas a role for either the carbonyl or the amide group of threonine is suggested
Determinazione del rotundone, l'aroma pepato, nelle varietà principi della Valpolicella: Corvina e Corvinone
No full textMolecular dynamics study of the conformational behavior of a representative elastin building block: Boc-Gly-Val-Gly-Gly-Leu-OMe.
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