Decay and cooling of biomolecules in an electrostatic storage ring

S. Tomita

Department of Physics and AstronomyUniversity of Aarhus

DK-8000 Aarhus C, Denmark

June 27 -July 2, 2003      4rth annual LEIF meeting - Belfast, N. Ireland

Ubiquitin

76 amino acid protein8.6 k amu

40 Å

Helical structure: helixSheet structure: sheets

Common amino acids

Photo absorption in solution

Photo absorption

Tryptophan

Tyrosine

Phenylalanine

Absorption

Wavelength

Tryptophan 280 nm

Tyrosine 274 nm

Phenylalanine 257 nm

Molecules investigated

NH

CH

O

C

CH2

CH2

CH2

CH2

NH2

H NH

CH

O

C

CH2 CH

CNH

CC

CHCH

CH

CH

NH

CH

O

C

CH2

CH2

CH2

CH2

NH2

OH

CH

C

NH

CH2

CH

NH2 COOH

C

CH

CH

CHCH

Lys-Trp-Lys Trp

Electrospray

J.B. Fenn (1988)

Nobel Prize in Chemistry (2002)

~3kV

~1cm

~10 M/L~1 L/min

Electrospray Source

1 mbar 10-3 mbar 10-5 mbar 10-6 mbar

Rotarypump

Turbopump

Turbopump

Heatedcapillary

ESI needle4kV

Fused silicacapillary

22 pole Ion trap

Tube lensSkimmer

OctapoleLenses

Acceleration tube

ELISA

1 mDetector for neutrals

Laser

Accelerator with electrospray ion source

Magnet

Laser power meter

Injection

Channeltron

t

Cou

nt

s

Pulsed Alexandrite Laser240-270nm (3rd harmonic)Pulsed NdYAG Laser266nm (4th harmonic)

Photo absorption in solution

Heating by photo absorption

h

Tr

1/t decay law

))(exp( tEkg

dEtEkEkgtI ))(exp()()(

0))(exp()()(')(/)(' tEkEkEtkEkEk10 12 14 16 18 20

0.0

0.2

0.4

0.6

0.8

1.0

t=100 st = 1 ms t=10 s

t=0

g(E

)

Internal energy (eV)

Distribution at time t

Yield of decay

Maximum at Em(t)1/k = t at Em(t)

ttI /1)(

-15 -10 -5 0 5 10 15 20101

102

103

104

105

106

Co

un

ts

Time (ms)

[Lys-Trp-Lys+H]+ 266nm

NH

CH

O

C

CH2

CH2

CH2

CH2

NH2

H NH

CH

O

C

CH2 CH

CNH

CC

CHCH

CH

CH

NH

CH

O

C

CH2

CH2

CH2

CH2

NH2

OH

Injection

Laser

20 21 22 23 24 25100

101

102

103

Co

un

ts

Time (ms)

[Lys-Trp-Lys+H]+

20 21 22 23 24 25101

102

103

104

Co

un

ts

Time (ms)

243nm E = 5.10 eV = 0.48ms

260nm E = 4.77 eV = 0.86ms

Lower photon energyLonger life time

Higher photon energyShorter life time

1.10 1.15 1.20 1.25 1.30102

103

104

266nm260nm

De

cay

rate

(s-1

)

1/T (10-3K-1)

A=1.51010 s-1

Eb=1.10 eV

243nm

Arrhenius plot

We can determine pre-exponential factor and dissociation energy.

Tk

ETk

B

dexp)(

0 100 200 300 400 500 600 700 800 900 10000

1

2

3

4

5

6

7

8

9

10

Inte

rna

l en

erg

y (e

V)

Temperature (K)

243nm260nm

Dependence on temperature of ion trap

0 5 10 15 20101

102

103

104

105

106

Counts

Time (ms)

HOTCOLD

Temperature of ion trap

0 5 10 15 20101

102

103

104

105

106

Coutn

s

Time (ms)

[Trp+H]+ + 250nm

0 20 40 60 80101

102

103

104

105

Co

un

ts

Time (ms)

Injection Laser

CH

C

NH

CH2

CH

NH2 COOH

C

CH

CH

CHCH

10-1 100 101101

102

103

104

Counts

Time (ms)

1/t

Fluorescence

Quantum yield

SolventAmino Acid Polypeptide

Emission Quantum Emission Quantum

Phenylalanine DMSO 282 0.02 284 0.006

Tyrosine DMSO 306 0.27 309 0.06

Tyrosine H20 303 0.21 -- --

Tryptophan DMSO 340 0.81 333 0.67

Tryptophan H20 340 0.19 333. 0.02

Quantum yield is very sensitive to the environment.

(Amino Acid) > (Polypeptide)DMSO > H20

Summary

Lys-Trp-Lys Narrow internal energy distribution Exponential decay after photo absorption Statistical decay through ergonic process Determination of dissociation energy

Trp 1/t Decay Due to high fluorescence quantum yield?

Collaborators

Stockholm

H. Cederquist

H.T. Schmidt

J. Jensen

H. Zettergren

CAEN

B.A. Huber

B. Manil

L. Maunoury

Canada

J.S. Forstar

Group at Univ. of Aarhus

P. Hvelplund J.U. Andersen S.B. Nielsen J. Rangama B. Liu