Grupo de Espectroscopia Molecular, Unidad Asociada CSIC
Laboratorios de Espectroscopia y Bioespectroscopia
Edificio Quifima. Parque CientíficoUniversidad de Valladolid
M. VARELA, C. CABEZAS AND J. L. ALONSO
ROTATIONAL STUDY OF NATURAL AMINO ACID GLUTAMINE
AIM: SYSTEMATIC STUDY OF PROTEOGENIC AMINO ACIDS
H2N
O
OH
O
OH
NH2
O
OH
NH2
O
OH
NH2
O
OH
NH2NH
O
OH
O
OH
NH2
OH O
OH
NH2O
HO
O
OH
NH2
O
HO
O
OH
NH2O
H2N
O
OH
NH2
O
OH
NH2HO
O
OH
NH2
S
HN
O
OH
NH2
O
OH
NH2
O
H2N
N
HN
O
OH
NH2
O
OH
NH2
H2N
O
OH
NH2
NH
NH
H2N
GLY ALA VAL ILE LEU PRO
SER CYSO
OH
NH2
HS
THR GLUASP ASN
PHE TYR
MET
TRP
O
OH
NH2
HO
GLN
HIS
LYSARG
Aliphatic with non-polar side chain
Aliphatic with polar side chain
Aromatic side chain
O
OH
NH2
O
H2N
CONFORMATIONAL STUDY OF GLUTAMINE: WHAT CAN WE EXPECT?
R = –CH2CH2C(O)NH2
Glutamine presents high flexibility Great number of low energy conformers
Ab initio calculations predict up to 12 conformations in a energy window of 900 cm -1
ΔEMP2/cm-1 1370 850 1130 1158 1071 790
ΔGMP2/cm-1 507 669 712 747 863 865
ΔEMP2/cm-1 179 0 380 858 1400 959
ΔGMP2/cm-1 0 106 140 418 669 471
Glutamine presents high flexibility Great number of low energy conformers
Glutamine possesses two 14N nuclei Very complex hyperfine structure
14N nucleus has non spherical nuclear charge distribution
Q ≠ 0Interaction with molecular
electric field gradient
CONFORMATIONAL STUDY OF GLUTAMINE: WHAT CAN WE EXPECT?
O
OH
NH2
O
H2N
FT-MW Spectrometer Fabry-Pérot Resonator
Picosecond Laser
4-10 GHz Frequency Range
EXPERIMENTAL: LA-MB-FTMW SPECTROSCOPY
Jet
Nd:YAG laser
Rotary
Diffusionpump
Glutaminesample
Laser
Gas pulse
Laser pulse
EXPERIMENTAL: LA-MB-FTMW SPECTROSCOPY
Ne
FT-MWspectrometer
Polarization
MW field
Rotary
Diffusionpump
MW pulse
Jet
Ne
EXPERIMENTAL: LA-MB-FTMW SPECTROSCOPY
Gas pulse
Laser pulse
Molecular emission
FT
Detection
Detection
Frequency-domain
Rotary
Diffusionpump
FT-MWspectrometer
Time-domain
EXPERIMENTAL: LA-MB-FTMW SPECTROSCOPY
MW pulse
Gas pulse
Laser pulse
Ne
RESULTS
303-202
313-212 312-211
Wide frequency scans covering up to 4 GHz revealed the rotational signatures of only one rotamer
Conformer I Conformer II Conformer III Conformer IV2023.7 2170.4 2456.4 2890.3947.4 898.9 739.2 683.6903.9 742.2 665.5 642.3
-0.60 -0.40 -1.65 -0.711.96 0.66 0.66 0.90-1.36 -0.26 0.99 -0.18
1.72 -1.93 -4.26 -2.91-3.76 1.99 2.49 2.332.04 -0.06 1.77 0.58
- - - -- - - -
∆E/cm-1 179 0 380 858∆G/cm-1 0 106 140 418
RESULTS
Rotamer A
A/MHz 2467.70941(14)B/MHz 727.94433(22)C/MHz 655.81028(16)
14N amide
χaa /MHz -1.5447(19)
χbb /MHz 0.6267(15)
χcc /MHz 0.9179(15)14N amine
χaa/MHz -4.0736(75)
χbb/MHz 2.3760(94)
χcc /MHz 1.6976(94)
N 67
σ /kHz 2.4
? ?
PRESENT RESULTS: BROADBAND FTMW SPECTROSCOPY
Experimental details in talk TD07
CP-FTMW + LASER ABLATION SOURCE
6000 7000 8000 9000 10000 11000 12000
PRESENT RESULTS: BROADBAND FTMW SPECTROSCOPY
6-12 GHZ Broadband Rotational Spectrum with 40000 FID
515-414
505-404
514-413523-422
414-313
404-303
413-312
423-322
Rotamer A
Rotamer B
PRESENT RESULTS: BROADBAND FTMW SPECTROSCOPY
Conformer I Conformer II Conformer IV2023.7 2170.4 2890.3947.4 898.9 683.6903.9 742.2 642.3
-0.60 -0.40 -0.711.96 0.66 0.90-1.36 -0.26 -0.18
1.72 -1.93 -2.91-3.76 1.99 2.332.04 -0.06 0.58
- - -- - -
∆E/cm-1 179 0 858∆G/cm-1 0 106 418
PRESENT RESULTS: BROADBAND FTMW SPECTROSCOPY
Rotamer B
A/MHz 2124.4 (28)B/MHz 847.8152 (72)C/MHz 805.666 (21)
14N amide
χaa /MHz -
χbb /MHz -
χcc /MHz -14N amine
χaa/MHz -
χbb/MHz -
χcc /MHz -
N 21
σ /kHz 5.0
SUMMARY
So far, the rotational spectra of two conformers of Glutamine have been
observed
Investigation of the 14N 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 2010- 19008
CSD 2009-00038 Molecular Astrophysics
Grants VA070A08 and CIP13/01
Grupo de Espectroscopia Molecular (GEM) Laboratorios de
Espectroscopia y Bioespectroscopia, Unidad Asociada CSIC, UVa,Valladolid, Spain