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