Mass spectrometry of pertrimethylsilyl oligosaccharides containing fructose units

TetrahedronLetters Do. 26, pp. 2367-2370,1971. PergamonPress. Printed in Great Britain.

MASS SEXTE~Y

OF FRUCTOSE CONTAINIIJGOLIGOSACCHARIDES

J.P. kamerling and J.F.G. Vliegenthart Laboratory of Orgsnio Chemistry University of Utreoht, The Netherlands J. Vink and J.J. de Ridder Laboratory of Analytical Chemistry University of Utreoht, The Netherlands (Receivedin UK 17 day 1971; accepted in UK for publication26 May 1971)

In our studies on the structure determination of oligosaccharidesby mass spectrometry,we observed that hexosyl oligosaocharidescontaining fructose units behaved differently to thoae consisting of aldohexoses only. The mass speotrum of pertrimethylsilyl-sucrose'(II) shows the presence of the fragment ion at m/e 437 (C,7H4,05Si4)with a rather high abundance oomparsd to the peak at m/e 435 (figure I). In the spectra of TMS-disaccharides containing only aldohexoses the relative intensity of the peak at m/e 437 is always smaller than that of the peak at m/e 435 '. The usefulness of the fragment ion at m/e 437 or its analogue at m/e 815 as described below, for the oharaoterizationof fruotose oontaining oligosaooharidesmay be illustrated by the I4 examples given in Table A. In the mass spectra of TMS-aldohexosyl-(I+ I)- or (i+

2)-fruotoses the peak at

m/e 437 has a high intensity. For the oomponents with the glyoosidic bond located on the remaining positions viz. I + 3, l-, 4, I * 5 or l+

6, the intensity of m/e 437

is about the same as in the TldS-aldohexosyl-aldohexoses. However, these fructose containing disaccharides are oharacterized by the presenoe of a peak at m/e 815 (Mt minus 'CH20ThS) being high in comparison to the peak at m/e 813 (Mt minus 'CH3 minus TMSOH). The formation of m/e 815 and m/e 813 in these disaccharides seems to be equivalznt to the formation of m/e 437 and m/e 435 in monosaccharides 2s3. In the latter case the relative intensities of the peaks at m/e 437 and m/e 435 can be used to distinguish 2-ketohexoses from aldohexoses 495. The formation of the fragment ion at m/e 437 in I+

I disaccharides results from

the cleavage of the bond between Cl and C2 of the fructose unit, correspondingto the elimination of 'CH20TkiSin TM-fructose 5. For I + 2 disaccharides,we suggest the following fragmentation (figure 2), via pertrimethylsilyl-fructoseas an intermediate.

2367

a-D-Gp(l+

P-D-Galp(l+

a-D-Gp( l+

a-D-Gp(ld

~D-Bu~-(P+

III

IV

V

VI

vn

b ’

b

b

6)-~-c b 6)-a-D-Gp(l+

p-D-Frug-(2+ 6)-a-D-Gp(l+

~-D-FIu~-(~-~~)+D-Fxw~(~+

a-I!-Galp(

XIV

6)-a-D-Galp(l+

0.7

2

13

Fru 0 Fructose 2 = pyranose f - furanose

' J.T. Baker Chemioals B.V. d Pierce Chemicals Company

' EGA-Chsmie K.G.

f In kestose x the intensities of m/e 813 and m/e 815 have been oorreoted for the isotopic contributionof the intense peak at m/e 811.

Gal = Galsotose

37

0.3

2 1

0.2

12

2

73

0.8

0.4

17

3

16

(1 0.8

39

2

(1

27

0.3

22

96

102

168

62

0.1

2

G I Glucose

2)-P-D-F'ru~(=staohyose)e

0.5

57

1

0.2

114

1

3

5

4

1

2

4

7

3

1 0.1

8

8

5

7

2

37

1

5

108

5

0.6

2.6

8.8

5.9

8.1

1.6

1.3

1.7

1.1

0.5

0.9

1.5

7.4

1.3

Relative intensities a e 21 m/e 435 m/e 437 m/e 813 m/e 815 .Wm e 204

b gifts (see acknowledgements)

* in psro~tagea of m/e 361

l+

2)-P-D-Frd(Ineokestose) b

2)-P-D-Fz&-6-kestose) b

2)-P-D-Ii'&-1-kestose) b9f

XIII

2)-@-D_tig-(6+

XII

2)-P-D-hg-(l+

a-+Gp(l-b

a-SGp(l+

Pmeleeitose) '

XI

l)-a-D-Gg(

X

2)-P-D-FIX&~+

a-D-GE-(l+

IX

VIII a-D-Galp(1-b 6)-a-D-Gp-(l-b2)-P-D-Fruf(=raffinose)'

6)-D-c

6)-Pl?rd(-pdatinose) '

5)-D-F-rq(-leuorose)

4)-D-Fru(-laotulose)'

3)-D-F'ru(=turanose) d

P)-p-D-Frug( =~uorose)

e-D-Q-( l-+ 1).PFhl

a-D-Gp(l+

I

II

Carbohydrates

TABLEA

2369

X0.26

However, au ion at m/e 540 oorreeponding to thia intermediate wae not present in

8

aimifiaant abundanoe. The mam

apeotrum of ~-P-D-f~otofuranoayl-(2-)

6)+gluooee

(VII) aleo shore

an intense peak at m/e 437. However, in the TMS-aldohexosyl-(14 6)-aldohexoeea this peek bss a low intensity (m/e 437