511546-75-1Relevant academic research and scientific papers
Lanthanide(III) complexes with two hexapeptides incorporating unnatural chelating amino acids: Secondary structure and stability
Cisnetti, Federico,Gateau, Christelle,Lebrun, Colette,Delangle, Pascale
experimental part, p. 7456 - 7469 (2010/03/24)
Unnatural metal-chelating amino acids bearing aminodiacetate side-chains have been introduced into two hexapeptides to obtain efficient lanthanide-binding peptides. The synthesis of the enantiopure Fmoc-Ada.,(tBu)2-OH synthons is described with overall yields of 32 and 50% for n = 2 and n = 3 side-chain carbon atoms, respectively. The two peptides AcWAdanPGAdanGNH2 (Pn) were synthesized from the protected synthons by standard solid-phase peptide synthesis. Studies of the lanthanide complexes of the two peptides P" by luminescence titrations, mass spectrometry, circular dichroism, and solution NMR spectroscopy demonstrate that the Ada., chain length has a dramatic effect on the complexation properties. Indeed, the flexible compound P3 forms a mononuclear complex of moderate stability (β11 = 10 9.9), which tends to transform into a binuclear species in the presence of excess of the metal ion. Interestingly, the more compact peptide P2 provides stable Ln3+ complexes with the exclusive formation of the mononuclear LnP2 adduct. The stability constant of TbP2 is two orders of magnitude higher (β11 = 10 12.1) than that measured for P3. The 800 MHz NMR spectrum of the La3+ complex of P2 evidences a well-defined type II ss-turn as well as a hydrophobic Trp(indole)-Pro interaction. These interactions exemplify the non-innocent character of the peptide spacer in the complex LaP2 as well as the role of a peptide secondary structure in the stabilization of metal complexes.
Opioid peptides: synthesis and biological properties of [(N gamma-glucosyl,N gamma-methoxy)-alpha, gamma-diamino-(S)-butanoyl]4-deltorphin-1-neoglycopeptide and related analogues.
Filira, Fernando,Biondi, Barbara,Biondi, Laura,Giannini, Elisa,Gobbo, Marina,Negri, Lucia,Rocchi, Raniero
, p. 3059 - 3063 (2007/10/03)
The [D-Ala2]deltorphin 1 sequence in which the aspartic acid residue is replaced by the N gamma-OCH3-alpha, gamma-diamino (S) butanoyl residue was synthesized using the Fmoc-chemistry-based solid phase procedure. The resulting deltorphin analogue was chemoselectively glucosylated by reaction with unprotected D-glucose (Glc). The Asn4-, (2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-galactopyranosyl)-Asn4- and the (2-acetamido-2-deoxy-D-galactopyranosyl)-Asn4-deltorphin I were also prepared for comparison. The affinity of the new compounds for the delta-opioid receptor was expressed by the inhibition constant (Ki) of the binding of the delta-receptor selective ligand [3H]naltrindole (NTI) to rat brain membrane preparations. The in vitro biological activity of the synthetic peptides was compared with that of the mu-opioid receptor agonist dermorphin in guinea pig ileum (GPI) preparations and with that of the delta-opioid receptor agonist deltorphin I in mouse vas deferens (MVD) preparations. The substitution of Asp4 with Asn failed to affect drastically the Ki and IC50 values for delta-sites, suggesting that an electrostatic interaction does not play an essential role in the binding to delta-opioid sites. The steric hindrance of the side chain of the residue in position 4 affects binding to delta-sites. The increase of the Ki value is smaller when the sugar-peptide linkage involves the gamma-nitrogen of the Dab residue in comparison with the Asn amide side chain.
Synthesis of a serine-based neuraminic acid C-glycoside
Wang, Qun,Linhardt, Robert J.
, p. 2668 - 2672 (2007/10/03)
Cell-surface carbohydrates are classified by the nature of their linkages to the protein as either N-linked or O-linked. O- and N-glycans are involved in a number of important biological functions. These activities can be lost on glycoprotein catabolism w
