RESUMEN
Protein interaction domains (PIDs) play a critical role in signal transduction. One PID of great interest is the PDZ domain, a 100 amino-acid-residue domain. Most PDZ domains recognize short, C-terminal peptide motives. In the heterodimer of the nNOS-PDZ domain and the alpha-syntrophin-PDZ domain, however, one PDZ domain forms a beta-finger that binds to the other PDZ domain. We show here that cyclic peptides derived from the beta-finger of the nNOS-PDZ domain can bind the syntrophin-PDZ domain in the same manner as the whole domain. The structure of three "finger-peptides" of different size has been determined and the binding investigated using calorimetry and NMR-titration experiments.
Asunto(s)
Óxido Nítrico Sintasa de Tipo I/química , Dominios PDZ , Péptidos Cíclicos/química , Secuencia de Aminoácidos , Proteínas Asociadas a la Distrofina/química , Datos de Secuencia Molecular , Óxido Nítrico Sintasa de Tipo I/síntesis química , Resonancia Magnética Nuclear Biomolecular , Péptidos Cíclicos/síntesis química , Unión ProteicaRESUMEN
Three photochromic dithienylethene-linker-conjugates with an adamantane core containing different spacer lengths and footprint areas with carboxylic anchoring groups are synthesized. The synthetic routes start either from the ethynylene-linker 5 or the iodo-substituted linker 8. Reaction conditions for the final Sonogashira coupling step between ethynylene-linker 5 with the chloro-substituted dithienylethene 4 in the presence of [PdCl(2)(CH(3)CN)(2)]/X-Phos and Cs(2)CO(3) or K(3)PO(4) are optimized using 2-chloro-5-methylthiophene (9) and triethylsilylacetylene or triisopropylsilylacetylene (10a,b) as model compounds. Experimental conditions are found to suppress the activation of the C(sp)-Si bond in TIPS-acetylene 10b, a reaction leading to a subsequent cross-coupling reaction to form by-product 12. Furthermore, activation of the C(sp)-Si bond in the presence of the fluorinated backbone of the chloro-substituted dithienylethene 4 can also be prevented. The photochromic properties of the conjugate 3 and its precursor dithienylethene 7b are also investigated.