Grupo de Espectroscopia Molecular, Unidad Asociada CSIC Laboratorios de Espectroscopia y Bioespectroscopia Edificio Quifima. Parque Científico Universidad de Valladolid M. VARELA, C. CABEZAS AND J. L. ALONSO ROTATIONAL STUDY OF NATURAL AMINO ACID GLUTAMINE
AIM: SYSTEMATIC STUDY OF PROTEOGENIC AMINO ACIDS GLYALAVALILELEU PR O SERCYSTHRGLUASPASN PHETYR ME T TRP GLN HIS LYS AR G Aliphatic with non-polar side chain Aliphatic with polar side chain Aromatic side chain
CONFORMATIONAL STUDY OF GLUTAMINE: WHAT CAN WE EXPECT? R = –CH 2 CH 2 C(O)NH 2 Glutamine presents high flexibilityGreat number of low energy conformers Ab initio calculations predict up to 12 conformations in a energy window of 900 cm -1 ΔE MP2 /cm ΔG MP2 /cm ΔE MP2 /cm ΔG MP2 /cm
Glutamine presents high flexibilityGreat number of low energy conformers Glutamine possesses two 14 N nucleiVery complex hyperfine structure 14 N nucleus has non spherical nuclear charge distribution Q ≠ 0 Interaction with molecular electric field gradient CONFORMATIONAL STUDY OF GLUTAMINE: WHAT CAN WE EXPECT?
FT-MW Spectrometer Fabry-Pérot Resonator Picosecond Laser 4-10 GHz Frequency Range EXPERIMENTAL: LA-MB-FTMW SPECTROSCOPY
Jet Nd:YAG laser Rotary Diffusion pump Glutamine sample Laser Gas pulseLaser pulse EXPERIMENTAL: LA-MB-FTMW SPECTROSCOPY Ne
FT-MW spectrometer Polarization MW field Rotary Diffusion pump MW pulse Jet Ne EXPERIMENTAL: LA-MB-FTMW SPECTROSCOPY Gas pulseLaser pulse
Molecular emission FT Detection Frequency-domain Rotary Diffusion pump FT-MW spectrometer Time-domain EXPERIMENTAL: LA-MB-FTMW SPECTROSCOPY MW pulse Gas pulseLaser pulse Ne
RESULTS Wide frequency scans covering up to 4 GHz revealed the rotational signatures of only one rotamer
Conformer IConformer IIConformer IIIConformer IV ∆E/cm ∆G/cm RESULTS Rotamer A A/MHz (14) B/MHz (22) C/MHz (16) 14 N amide χ aa /MHz (19) χ bb /MHz0.6267(15) χ cc /MHz0.9179(15) 14 N amine χ aa /MHz (75) χ bb /MHz2.3760(94) χ cc /MHz1.6976(94) N 67 σ /kHz 2.4
PRESENT RESULTS: BROADBAND FTMW SPECTROSCOPY Experimental details in talk TD07 CP-FTMW + LASER ABLATION SOURCE
PRESENT RESULTS: BROADBAND FTMW SPECTROSCOPY 6-12 GHZ Broadband Rotational Spectrum with FID
Rotamer A Rotamer B PRESENT RESULTS: BROADBAND FTMW SPECTROSCOPY
Conformer IConformer IIConformer IV ∆E/cm ∆G/cm PRESENT RESULTS: BROADBAND FTMW SPECTROSCOPY Rotamer B A/MHz (28) B/MHz (72) C/MHz (21) 14 N amide χ aa /MHz- χ bb /MHz- χ cc /MHz- 14 N amine χ aa /MHz- χ bb /MHz- χ cc /MHz- N 21 σ /kHz 5.0
SUMMARY So far, the rotational spectra of two conformers of Glutamine have been observed Investigation of the 14 N nuclear quadrupole hyperfine structure for rotamer II is needed to get the final assignment Probably more species will be identified in the broadband FTMW spectrum
ACKNOWLEDGMENTS Grant CTQ CSD Molecular Astrophysics Grants VA070A08 and CIP13/01 Grupo de Espectroscopia Molecular (GEM) Laboratorios de Espectroscopia y Bioespectroscopia, Unidad Asociada CSIC, UVa,Valladolid, Spain