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ROTATIONAL STUDY OF NATURAL
AMINO ACID GLUTAMINE
M. VARELA, C. CABEZAS AND J. L. ALONSO
Grupo de Espectroscopia Molecular, Unidad Asociada CSIC
Laboratorios de Espectroscopia y Bioespectroscopia
Edificio Quifima. Parque Científico
Universidad de Valladolid
AIM: SYSTEMATIC STUDY OF PROTEOGENIC AMINO
ACIDS
GLY
ALA
VAL
O
O
H 2N
O
OH
HS
NH2
S
ME
T
OH
NH2
OH
HO
NH2
NH2
H 2N
N
H
TYR
O
NH2
LYS
O
HO
NH2
H2N
OH
NH2
TRP
HIS
O
O
H
N
OH
OH
HN
NH2
Aliphatic with polar
side chain
O
OH
OH
OH
O
NH2
O
H 2N
OH
NH2
OH
NH2
PHE
O
O
NH2
AR
G
NH
OH
O
ASN
OH HO
O
O
H 2N
GLU
O
GLN
O
NH
ASP
OH
Aliphatic with
non-polar side chain
OH
OH
NH2
O
OH
O
O
NH2
THR
O
PR
OO
OH
NH2
CYS
HO
O
OH
NH2
SER
LEU
O
OH
OH
ILE
NH2
N
NH2
Aromatic side chain
CONFORMATIONAL STUDY OF GLUTAMINE: WHAT
CAN WE EXPECT?
O
O
H 2N
R = –CH2CH2C(O)NH2
OH
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
ΔGMP2/cm-1
179
0
ΔEMP2/cm-1
ΔGMP2/cm-1
1370
507
0
106
850
669
380
140
1130
712
858
418
1158
747
1400
669
1071
863
959
471
790
865
CONFORMATIONAL STUDY OF GLUTAMINE: WHAT
CAN WE EXPECT?
O
O
H 2N
OH
NH2
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≠0
Interaction with molecular
electric field gradient
EXPERIMENTAL: LA-MB-FTMW SPECTROSCOPY
FT-MW
Spectrometer
Fabry-Pérot Resonator
Picosecond
Laser
4-10 GHz Frequency Range
EXPERIMENTAL: LA-MB-FTMW SPECTROSCOPY
Gas pulse
Ne
Laser pulse
Jet
Glutamine
sample
Diffusion
pump
Rotary
Nd:YAG laser
Laser
EXPERIMENTAL: LA-MB-FTMW SPECTROSCOPY
Gas pulse
FT-MW
spectrometer
Polarization
Laser pulse
MW pulse
Ne
Jet
MW field
Diffusion
pump
Rotary
EXPERIMENTAL: LA-MB-FTMW SPECTROSCOPY
FT-MW
spectrometer
Gas pulse
Ne
Laser pulse
MW pulse
Molecular emission
Detection
Detection
Diffusion
pump
Rotary
FT
Time-domain
Frequency-domain
RESULTS
Wide frequency scans covering up to 4 GHz revealed the rotational signatures
of only one rotamer
303-202
313-212
312-211
RESULTS
A/MHz
B/MHz
C/MHz
14N amide
χaa /MHz
χbb /MHz
χcc /MHz
14N amine
χaa/MHz
χbb/MHz
χcc /MHz
N
σ /kHz
∆E/cm-1
∆G/cm-1
Rotamer A
2467.70941(14)
727.94433(22)
655.81028(16)
Conformer I
2023.7
947.4
903.9
Conformer II
2170.4
898.9
742.2
Conformer III
2456.4
739.2
665.5
Conformer IV
2890.3
683.6
642.3
-1.5447(19)
0.6267(15)
0.9179(15)
-0.60
1.96
-1.36
-0.40
0.66
-0.26
-1.65
0.66
0.99
-0.71
0.90
-0.18
-4.0736(75)
2.3760(94)
1.6976(94)
67
2.4
1.72
-3.76
2.04
179
0
-1.93
1.99
-0.06
0
106
-4.26
2.49
1.77
380
140
-2.91
2.33
0.58
858
418
PRESENT RESULTS: BROADBAND FTMW SPECTROSCOPY
CP-FTMW + LASER ABLATION SOURCE
Experimental details in talk TD07
PRESENT RESULTS: BROADBAND FTMW SPECTROSCOPY
6-12 GHZ Broadband Rotational Spectrum with 40000 FID
6000
7000
8000
9000
10000
11000
12000
PRESENT RESULTS: BROADBAND FTMW
SPECTROSCOPY
404-303
414-313
413-312
Rotamer B
423-322
505-404
Rotamer A
515-414
523-422
514-413
PRESENT RESULTS: BROADBAND FTMW
SPECTROSCOPY
A/MHz
B/MHz
C/MHz
14N amide
χaa /MHz
χbb /MHz
χcc /MHz
14N amine
χaa/MHz
χbb/MHz
χcc /MHz
N
σ /kHz
∆E/cm-1
∆G/cm-1
Rotamer B
2124.4 (28)
847.8152 (72)
805.666 (21)
Conformer I
2023.7
947.4
903.9
Conformer II
2170.4
898.9
742.2
Conformer IV
2890.3
683.6
642.3
-
-0.60
1.96
-1.36
-0.40
0.66
-0.26
-0.71
0.90
-0.18
1.72
-3.76
2.04
179
0
-1.93
1.99
-0.06
0
106
-2.91
2.33
0.58
858
418
21
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
Grupo de Espectroscopia Molecular (GEM)
Laboratorios de Espectroscopia y
Bioespectroscopia, Unidad Asociada CSIC,
UVa,Valladolid, Spain
Grant CTQ 2010- 19008
CSD 2009-00038 Molecular Astrophysics
Grants VA070A08 and CIP13/01