Vibrational characterization of L-leucine phosphonate analogues: FT-IR, FT-Raman, and SERS spectroscopy studies and DFT calculations.

This study reports the Raman (FT-Raman) and absorption infrared (FT-IR) spectra, based on calculated wavenumbers and normal modes of vibrations, of the following compounds: L-Leu-D-NH-CH(Me)-PO(3)H(2) (LI), L-Leu-NH-C(Me)(2)-PO(3)H(2) (LII), L-Leu-D-NH-CH(Et)-PO(3)H(2) (LIII), L-Leu-L-NH-CH(Et)-PO(3)H(2) (LIV), L-Leu-L-NH-CH(EtOH)-PO(3)H(2) (LV), L-Leu-NH-C(Me)(Et)-PO(3)H(2) (LVI), L-Leu-L-NH-CH(PrA)-PO(3)H(2) (LVII), L-Leu-L-NH-CH(c-Pr)-PO(3)H(2) (LVIII), L-Leu-L-NH-CH(t-Bu)-PO(3)H(2) (LIX), L-Leu-L-NH-CH(BuA)-PO(3)H(2) (LX), L-Leu-L-NH-CH(c-Bu)-PO(3)H(2) (LXI), and L-Leu-L-NH-C(Adm)-PO(3)H(2) (LXII). The equilibrium geometries and vibrational wavenumbers were calculated using density functional theory (DFT) at the B3LYP, 6-311++G** level using Gaussian 03, Raint, GaussSum 0.8, and Gar2ped software.

Potential induced changes in neuromedin B adsorption on Ag, Au, and Cu electrodes monitored by surface-enhanced Raman scattering.

Surface-enhanced Raman scattering (SERS), electrochemistry, and generalized two-dimensional correlation analysis (G2DCA) methods were used to define neuromedin B (NMB) ordered superstructures on Ag, Au, and Cu electrode surfaces at different applied electrode potentials in an aqueous solution at physiological pH. The orientation of NMB and the adsorption mechanism were determined based on the analysis of enhancement, broadness, and shift in wavenumber of particular bands, which allow drawing some conclusions about NMB geometry and changes in this geometry upon change of the electrode type and applied electrode potential. The presented data demonstrated that NMB deposited onto the Ag, Au, and Cu electrode surfaces showed bands due to vibrations of the moieties that were in contact/close proximity to the electrode surfaces and thus were located on the same side of the polypeptide backbone.

Structure and binding of specifically mutated neurotensin fragments on a silver substrate: vibrational studies.

Here, we report a systematic study showing an analogy between the activities of peptide structural component interactions with both a metal substrate and a G-protein-coupled seven-transmembrane receptor. In the present work, N-terminal fragments of human neurotensin (NT), NT(1-6), NT(1-8), and NT(1-11), and C-terminal fragments of human neurotensin, NT(8-13) and NT(9-13), as well as six specifically mutated analogues with the following modifications, Acetyl-NT(8-13), [Dab(9)]NT(8-13), [Lys(8),Lys(9)]NT(8-13), [Lys(8)-(®)-Lys(9)]NT(8-13), [Lys(9),Trp(11),Glu(12)]NT(8-13), and Boc[Lys(9),Leu(13)OMe]NT(9-13), were immobilized onto an electrochemically roughened silver electrode surface in an aqueous solution. The orientation of the adsorbed molecules and the adsorption mechanism were determined from surface-enhanced Raman scattering (SERS) spectra.

Structure of monolayers formed from neurotensin and its single-site mutants: vibrational spectroscopic studies.

The human, pig, and frog neurotensins and four single-site mutants of human neurotensin (NT), having the following modifications, [Gln(4)]NT, [Trp(11)]NT, [D-Trp(11)]NT, and [D-Tyr(11)]NT, were immobilized onto an electrochemically roughened silver electrode surface in an aqueous solution. The orientation of adsorbed molecules was determined from surface-enhanced Raman scattering (SERS) measurements. A comparison was made between these structures to determine how the change upon the mutation of the neurotensin structure influences its adsorption properties.

Neuromedin C: potential-dependent surface-enhanced Raman spectra in the far-red spectral region on silver, gold, and copper surfaces.

Neuromedin C (NMC) is a decapeptide (Gly-Asn-His-Trp-Ala-Val-Gly-His-Leu-Met-NH(2)) that acts as a growth factor in a wide range of tumors including carcinomas of the pancreas, stomach, breast, prostate, and colon. We report surface-enhanced Raman spectra (SERS) of NMC on electrochemically roughened Ag, Au, and Cu electrode surfaces over an electrode potential range varying from +0.200 to -1.