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Biomedical subjects

Juan B Blanco

Publications and source records attributed to Juan B Blanco.

7 recordsLinked to original sources
PubMed2006

6-N,N-dimethylamino-2,3-naphthalimide: a new environment-sensitive fluorescent probe in delta- and mu-selective opioid peptides.

A new environment-sensitive fluorophore, 6-N,N-(dimethylamino)-2,3-naphthalimide (6DMN) was introduced in the delta-selective opioid peptide agonist H-Dmt-Tic-Glu-NH(2) and in the mu-selective opioid peptide agonist endomorphin-2 (H-Tyr-Pro-Phe-Phe-NH(2)). Environment-sensitive fluorophores are a special class of chromophores that generally exhibit a low quantum yield in aqueous solution but become highly fluorescent in nonpolar solvents or when bound to hydrophobic sites in proteins or membranes. New fluorescent delta-selective irreversible antagonists (H-Dmt-Tic-Glu-NH-(CH(2))(5)-CO-Dap(6DMN)-NH(2) (1) and H-Dmt-Tic-Glu-Dap(6DMN)-NH(2) (2)) were identified as potential fluorescent probes showing good properties for use in studies of distribution and internalization of delta receptors by confocal laser scanning microscopy.

Animals↗
PubMed2005

High affinity, sequence specific DNA binding by synthetic tripyrrole-peptide conjugates.

Linking the basic region of a bZIP transcription factor to a distamycin-like tripyrrole peptide by means of a nitrogen-containing tether produces a hybrid capable of high-affinity recognition of specific, designated DNA sequences. The importance of the nitrogen in the tether is shown by the considerable reduction in affinity (more than 10-fold) caused by its replacement with an ether linkage. Attachment of an aminopropyl chain on the pyrrole adjacent to the pyrrole bearing the nitrogen-containing tether increases affinity approximately one order of magnitude. These results confirm that a suitable location of protonated amine groups on designed DNA-binding peptides provides for higher affinities, most probably because of the generation of salt bridged contacts with the phosphodiester backbone.

DNA↗
PubMed2005

Photophysics and biological applications of the environment-sensitive fluorophore 6-N,N-dimethylamino-2,3-naphthalimide.

We have synthesized a new environment-sensitive fluorophore, 6-N,N-dimethylamino-2,3-naphthalimide (6DMN). This chromophore exhibits valuable fluorescent properties as a biological probe with emission in the 500-600 nm range and a marked response to changes in the environment polarity. The 6DMN fluorescence is red-shifted in polar protic environments, with the maximum emission intensity shifting more than 100 nm from 491 nm in toluene to 592 nm in water. Additionally, the fluorescence quantum yield decreases more than 100-fold from chloroform (Phi = 0.225) to water (Phi = 0.002). The scope and applications of the 6DMN probe are expanded with the synthesis of an Fmoc-protected amino acid derivative (5), which contains the fluorophore. This unnatural amino acid has been introduced into several peptides, demonstrating that it can be manipulated under standard solid-phase peptide synthesis conditions. Peptides incorporating the new residue can be implemented for monitoring protein-protein interactions as exemplified in studies with Src homology 2 (SH2) phosphotyrosine binding domains. The designed peptides exhibit a significant increase in the quantum yield of the long wavelength fluorescence emission band (596 nm) upon binding to selected SH2 domains (e.g., Crk SH2, Abl SH2, and PI3K SH2). The peptides can be used as ratiometric sensors, since the short wavelength band (460 nm) was found almost invariable throughout the titrations.

Amino Acids↗
PubMed2003

A synthetic miniprotein that binds specific DNA sequences by contacting both the major and the minor groove.

Attachment of a slightly modified basic region of a bZIP protein (GCN4) to a distamycin-related tripyrrole provides a bivalent system capable of binding with high affinity to specific DNA sequences. Appropriate adjustment of the linker between the two units has led to a hybrid that binds a 9 base-pair-long DNA site (TTTTATGAC) with low nanomolar affinity at 4 degrees C. Circular dichroism and gel retardation studies indicate that the binding occurs by simultaneous insertion of the bZIP basic region into the DNA major groove and the tripyrrole moiety into the minor groove of the flanking sequence. Analysis of hybrids bearing alternative linkers revealed that tight, specific binding is strongly dependent on the length and nature of the connecting unit.

Amino Acid Sequence↗