RESUMEN
Vibrational spectroscopy combined with machine learning has a great potential for forensic research. Portable Raman spectrometers are already being used by law-enforcement agencies to identify drugs. Several new technologies based on vibrational spectroscopy, that can be used in forensic science to analyze documents, gunshot traces, cloths, soil, hair, nails and lacquer, are being developed nowadays. The article considers the use of vibrational spectroscopy in forensic practice for conducting serological studies with an emphasis on the development of a universal method of identifying the main secretions of the body. The method allows to determine the time elapsed since the trace was made, as well as the phenotypic profile of host, including sex, race and age.
Asunto(s)
Medicina Legal , Aprendizaje Automático , Humanos , Medicina Legal/métodos , Espectrometría Raman/métodos , Análisis Espectral/métodosRESUMEN
Transient UV resonance Raman measurements excited within the amide pi --> pi transitions of a 21 unit alpha-helical peptide has for the first time determined a lower bound for the unfolding rate of the last alpha-helical turn to form a fully random coil peptide. A 3 ns T-jump is generated with 1.9 microm laser pulses, which are absorbed by water. Subsequent 3 ns 204 nm UV pulses excite the amide Raman spectra at delay times between 3 ns and 1 ms, to monitor the peptide conformational evolution. We find approximately 180 ns relaxation times which result in a rate constant of >5 x 10(6) s(-1) for unfolding of the last alpha-helical turn. Our data are inconsistent with slow alpha-helix nuclei melting.
Asunto(s)
Conformación Proteica , Estructura Secundaria de Proteína , Cinética , Espectrometría Raman , TermodinámicaRESUMEN
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). Our 206.5-nm excited Raman results indicate that the 1:2 AII:SDS complexation increases the AII beta-turn composition. We also used 228.9-nm Raman excitation to probe the local solvent accessibility of Tyr(4) (AII) in DPC and SDS micelles. Our Tyr (AII) solvent accessibility studies suggest that the Tyr residue is more exposed to the aqueous environment in SDS micelles than in DPC micelles.