UV Raman studies of peptide conformation demonstrate that betanova does not cooperatively unfold.

We used UV resonance Raman spectroscopy (UVRR) excited within the peptide bond pi --> pi* electronic transitions and within the aromatic amino acid pi --> pi* electronic transitions to examine the temperature dependence of the solution conformation of betanova, a 20-residue beta-sheet polypeptide [Kortemme, T., Ramirez-Alvarado, M., and Serrano, L.

Chromatographic detection of nitroaromatic and nitramine compounds by electrochemical reduction combined with photoluminescence following electron transfer.

The oxidizing agent tris(bipyridyl)ruthenium(III), or Ru-(bpy)(3)3+, is used as a postcolumn reagent for the detection of nitroaromatic and nitramine explosive compounds. After separation, the explosives are reduced electrochemically to oxidizable products such as hydroxlamines and nitrosamines, and these products react readily with Ru-(bpy)(3)3+ and Ru(bpy)(3)2+. The photoluminescence from the latter is used for detection.

UV resonance Raman study of angiotensin II conformation in nonaqueous environments: lipid micelles and acetonitrile.

We used 206.5-nm excited resonance Raman measurements to examine the angiotensin II (AII) secondary structure in H(2)O in the presence of dodecylphosphocholine (DPC) micelles, sodium dodecylsulfate (SDS) monomers and micelles, and in a 70% acetonitrile (ACN-d)-30% water solution. Our AII-SDS titration absorption studies indicate the formation of a 1:2 AII:SDS complex in which two negatively charged SDS molecules attach to the AII positively charged N terminus and to Arg(2).

Development of a liquid chromatographic method for picomole determination of S-sulfocysteine in trifluoroacetic acid extracts of neonatal rat brain.

Neonatal Sprague Dawley rat brain tissue was extracted with methanol, acetonitrile, acetic acid and trifluoroacetic acids (TFA). Among the extractants tested, 0.1 M TFA gave the highest recovery, 73.

Ultraviolet resonance Raman examination of horse apomyoglobin acid unfolding intermediates.

We have used UV resonance Raman spectroscopy to study the acid-induced denaturation of horse apomyoglobin (apoMb) between pH 7. 0 and 1.8.

Chromatographic detection using tris(2,2'-bipyridyl)ruthenium(III) as a fluorogenic electron-transfer reagent.

Tris(2,2'-bipyridyl)ruthenium can be excited to fluorescence by visible light (lambda abs 454 nm, lambda em 607 nm) when in the M(II) oxidation state, but not in the M(III) state. A novel chromatographic detection method using the non-fluorescent M(III) form of the complex as a postcolumn fluorogenic reagent is demonstrated. The M(III) form is a powerful oxidizing agent (E degree = 1.

Comparison of anion-exchange and ion-modified reversed-phase liquid chromatography for the determination of S-sulfocysteine.

A dual Hg-Au amalgam electrode is used to detect S-sulfocysteine (SSC) in this study. There exist two main components in the acetonitrile (ACN) rat brain extracts, namely, Cl- and GSSG (oxidized glutathione), that are active in our detection system (GSH is not extracted in ACN). Two strong anion-exchange columns from different companies were used to separate the samples under different conditions, but SSC and Cl- were not separated at the optimum detection pH of 5.

Determination of the pharmaceutical peptide TP9201 by post-column reaction with copper(II) followed by electrochemical detection.

An electrochemical detection method was applied to the determination of the synthetic peptide TP9201 (Telios Pharmaceuticals). The method utilizes reversed-phase HPLC, followed by post-column formation of Cu(II)-peptide complexes to render peptides electrochemically active via the Cu(III/II) couple. TP9201 is cyclic and N-amidated; the lack of a free amine precludes the use of typical fluorescent labeling reagents.

Voltammetry of extracellular dopamine in rat striatum during ICSS-like electrical stimulation of the medial forebrain bundle.

Fast-scan cyclic voltammetry in the striatum of anesthetized rats has been used to monitor extracellular dopamine during forced electrical stimulation of the media forebrain bundle using parameters that mimic intracranial self-stimulation. The temporal resolution provided by microelectrodes positioned very near sites of dopamine release allows resolution of the response to individual 500-ms stimulation trains separated by 500-ms intervals. Uptake inhibition by Nomifensine alters the resolution obtained at short times after initiation of stimulation.

Borate interference in surface-enhanced Raman spectroscopy of amines.

Interference from borate is observed in surface-enhanced Raman (SER) spectra of lysine and propylamine obtained with borohydride-reduced silver colloids. Borate bands are also observed in the spectra of other basic analytes, as well as when certain variations are made in the silver colloid preparation. The relative intensities of the analyte and borate bands depend on the pH of the colloid, the extent of oxidation of the colloid surface, and the relative adsorptivities of the analyte and borate.

Huperzine A--a potent acetylcholinesterase inhibitor of use in the treatment of Alzheimer's disease.

Huperzine A, 9-amino-13-ethylidene-11-methyl-4-azatricyclo [7.3.1.

Structural determinants of affinity for the phencyclidine binding site of the N-methyl-D-aspartate receptor complex: discovery of a rigid phencyclidine analogue of high binding affinity.

To learn more about the binding conformation of phencyclidine (PCP) and to arrive at analogues of higher affinity, which may serve as noncompetitive N-methyl-D-aspartate receptor antagonists, eight optically pure PCP analogues were designed with the aid of computer. These compounds represent conformationally constrained versions of PCP in which the motion of the phenyl ring is frozen, thus allowing a determination of the orientation of the phenyl ring relevant to binding. The analogues were synthesized by a Diels-Alder strategy and tested in a radioligand binding assay to evaluate their affinity for the PCP binding site of the N-methyl-D-aspartate receptor complex.