Vibrational Raman optical activity of disaccharides

Journal

of

MOLECULAR STRUCTURE ELSEVIER

Journal

of Molecular

Structure

349 (1995)

Raman

Vibrational

401-404

Activity

Optical

of

Disaccharides A.

F. Bell,

L. Hecht

Chemistry

and

Department,

L. D. Barron The

University,

Glasgow

G12 8QQ,

United

Kingdom.

1. INTRODUCTION Vibrational Raman

Raman

scattered

optical

light

from

circularly

polarized

solution

stereochemistry

particularly in

the

the

normal

anomeric

features

groups

assignments

to

is

the

the

together

by the

is

6 of

then two

a

C-O-C

bond

known

carbon

atom

hand

trapped

example

to

or

of

does

undergo

conformation

particular feature

Previous

here to

the are

studies

have

perspective,

relative

in determining

left

of

coupled on

including

and

attention

and

probe

extensively

a new

presented

and

u-

or

that the

as of

form

not

described

all

dominant

disposition

extends

the the

of

the

ROA

glycosidic

link

conformation

directly formula

on

the

whether the

Cl-01

links

is

to

This

link

carbon of

of

the

bond

glycosidic

numbering

can

atom

form 1, 2, 3,

then

residue.

atom

of link

on

of

may

the have

residue

axial

and

by

naming

oxygen scheme

If

it

a residue,

mixture

The

non-reducing

possible

joined

a residue,

an equilibrium

Figure 1 for the a(l-4) linked disaccharide, D-maltose. 0022-2860/95/$09.50 0 1995Elsevier Science B.V. All rights reserved SSDI 0022-2860(95)08794-X

carbon residue.

atomic

residues

a non-reducing

anomeric

a reducing

with

and

either carbon

is called

these

attached

D-glucose link.

and

producing

depending of

glycosidic

the

as

form

two

anomeric

and

mutarotation is

of

residue

the

involve

8-anomeric are

the

one

classification

structural

consist

involves

8-configuration

Further

atoms

link

anomeric

link

forms

in the

respectively. carbon

If the

the

it is free an u-

and

right

in

Carbohydrates

are

spectrum.

work

to

Cl-3 1.

stereochemistry

The

here

anomeric

anomeric

either

group C4,Sl.

discussed

in a single

other

ROA

difference

chiroptical

coordinates

information,

single

respect

a new

molecules

rich

intensity

polysaccharides.

another.

trapped

the

a

with

important

disaccharides

between 4, or

CH,OH

disaccharides

most

and

oligoAll

in

the ring

with

normal

provide

small

as

monosaccharide

of

around

molecules

biological

can

the

is emerging

as the

resulting

configuration,

hydroxyl

di-,

of

ROA

(ROA),

chiral light,

samples

modes that

central

which

incident

favourable

demonstrated

activity

is

is

equatorial, the

two

atom.

An

shown

in

402

Non-reducing residue

Reducing residue

OH 1 The structural

Figure

formula

and numbering

scheme

for

D-maltose

2. ROA OF DISACCHARIDES The ROA

spectra

number

of

signals

similar

intensities, The two

new

normal

important

Wavenumber

ROA

Table

arising

couplet

to

to

from

centred

Couplet

glycosidic

display

addition

to

have

types

quite

and width

disaccharide

of low

linkage

wavenumber

type and

configuration

many

different

and conformations.

of

have been

exo-

and

in monosaccharides link

calculated

has been

found

assigned

endocyclic

C61 with

for in all

glycosidic position of ROA

disaccharides

couplet

CCO, C71.

the disaccharides

ROA couplet

and sign

by

additional

1

Position

a

at w 430 and 917 cm-‘.

spectrum

mixtures

at IV 430 cm-’

residues

430 cm”)

the ROA

complex

in

can

linkage

are found (-

of

link,

signals

different

deformations the

only D-glucose

glycosidic

These

signals

in this region bending

the

for

signs,

of these

analysis

and OCO

containing

itself.

Glycoaidic

modes

coordinate COC

contributions A

sensitive

D-glucose

or even opposite

The normal CCC,

signals to

most

2.1 Low

of disaccharides

deconvoluted couplet

D-maltose

~~(1-4) ax.-eq.

431 (+,-)

31

D-cellobiose

p(l-4)

eq.-eq.

440 (-,+I

34

D-isomaltose

ar(l-6) ax.-eq.

424 (+,-)

39

D-gentiobiose

B(l-6)

eq.-eq.

420 (-,+)

41

D-laminaribiose

f5(1-3) eq.-eq.

425 (-,+)

33

D-trehalose

cr(l-1) ax.-ax.

431 (+,-I

19

width

403

consisting

of

D-glucose

and negative

at

positive

at

centred

within

the

ROA

high

that

the

generating spectrum making the

wavenumber change

it has similar centre

the ROA

signals.

D-glucose

important and

width

between

dependency

is

bands

contributing

for

going

This couplet is positive at species and negative at low

species.

The

fact

a-linked

to

non-reducing

B-linked

as no couplet that the rest of

is

signs

species

play

low and

couplet

the

and that

residue

In addition,

this

and that

in all the disaccharides

the

that

all the disaccharides from

origins of

so far.

a-linked

B-linked

it is possible

of

dependence Raman

for

strongly

deformations

a crucial

is in evidence the glycosidic

role

in

in the ROA link is also

a

Table

of

this

the

function signals

ROA

linkage of

together

ROA

I, which

with

lists

the centre

couplet, type

the

it

is

and

the

differences

in

the

appearance

of opposite

wavenumber

clear

that

width

of

together

there this

is

a

couplet.

with strong This

the

separation

of

the

parent

of

additional

Raman

bands

sign for the two

anomeric

forms.

ROA

L.l _5.0x103

Figure

2

The for

backscattered the

of

contributions.

inspection

sign

studied

for

on

anomeric of

From

residues wavenumber

a + 20 cm -’ range

signals

suggests about

high

range

cm-’

Raman ++ 350

to

(IR 1500

+

IL)

cm-’

and

ROA

in aqueous

(IR

-

solution.

IL)

spectra

of

D-maltose

404

2.2 The One

917 an-1

of

couplet

the

positive

D-glucose, the

at low is

has two

ar(l-61 linked couplet

and negative to

glycosidic

links

or-cyclodextrin

this

per

of

double

molecules

couplet

wavenumber

and

broaden

deformations

are

intimately

(In

is

of found

the

to

sign

collapse This

in the

in

In addition,

reversed

of

largest

value

in

D-maltose shift

indicates

modes

in

intensity

intensity,

clearly

normal

a

D-maltotriose,

is

the

groups

is

at w 917 cm-’ in

trimer,

than the

hydroxyl

considerably. involved

the

ac-cyclodextrin

greater

the

spectra

disaccharides.

in

and

ROA

centred

the 8-linked

magnitude

deuteration

disaccharide

at high wavenumber

in any of

D-isomaltose.

an order

Upon

in the

approximately

disaccharide,

is almost

features

not appear

found

encountered.)

Couplet

interesting

and does

intensity

which

Glycosidic

most

the this

usually and

to

that

lower C-O-H

responsible

for

this

couplet. In a normal repeating

coordinate

unit,

described

from

assigned

In

to

atoms

addition,

a

C-O-H

that

coordinates

of the glycosidic

C-O-H

hydrogen persist

ROA

found

some

degree

band

D-maltose

calculated

mode. can

be

to

in aqueous

band All

the

that

the of

at

above to

cm-’

cm-’

lead

for

the

coordinates

intramolecular

and

important

to

was

stretching

stretching

OZ-H.a.03’

was noted

and C3’-OH

923

C-O-C

D-maltose

is also

were

data

the

the ring

structure

solution

946

and C2-OH

observed

assigned with

suggest

crystal

at

is the dimer

link and contributions

Raman

link interacting the

which

but also the ring atoms

second

and

in

for

the or(l-4)

couplet

deformations, bond

to

a

of

deformation

conclusion and

this

sensitive

vibration

the linkage

deformations.

of amylose,

conformation

a

as a skeletal

not only

analysis

thought

the

to

generation

of this couplet. The

sign

consequence the two

change

in

D-isomaltose

of the different

molecules

linkage

relative

have the same absolute

This demonstrates

to

conformations

the conformational

D-maltose

these

configuration

sensitivity

two

is

probably

molecules

at all

adopt

the chiral

a as

centres.

of the couplet.

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L. D. Barron

2.

Z. Q. Wen,

L. Hecht

and L. Hecht,

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L. Hecht

and L. D. Barron,

4.

L. D. Barron,

5.

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Adv.

A. R. Gargaro

Spectrosc.,

21 (19941 235.

Protein

Science,

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443.

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L. D. Barron and L. Hecht, J. Am. Chem. Sot., P. Derreumaux

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11.5(1993) 28.5.

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Lagant,

Legrand

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