Characterization of the far ultraviolet optically active absorption bands of sugars by circular dichroism

BIOCHEMICAL

Vol. 30, No. 4, 1968

CHARACTERIZATION ABSORPTION

OF THE FAR ULTRAVIOLET OPTICALLY ACTIVE BANDS OF SUGARS BY CIRCULAR DICHROISM Irving

Department

Received

January

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

Listowsky’

of Biochemistry, Albert Einstein College of Medicine Yeshiva University, Bronx, New York 10461

2, 1968

In recent studies, the far ultmviolet a large number of sugars were related formations

in solution

study is an initial

and Sasha Englard

(Englard

optical

rotatory

to known features

et -- al.,

1966; Listowsky

report of the far ultmviolet

et -a al.,

circular

curves are evident

in the spectml

maxima for most simple sugars are expected accessible

to current

is clearly

discernible.

instrumentation,

The CD curves for D-glucose of the types of curves obtained

negative

an appreciable

for galactose.

dichroism

(Listowsky is evidently

et -- al., related

below

and D-galactose

is negligible

a change

1965; Pace et -- a I., 1964). to the negative

Senror Research Fellow,

active

absorption

band

1, are representative

In the spectral

positive

below

region

200 mu the

for glucose and

is chamcterized

of rotation

the

shorter than those

shown in figure

and becomes distinctly

that

of CD

200 mP and although

for both sugars, however

in direction

The present

portion

to appear at wavelengths

The ORD curve for D-galactose

data verify our previous conclusion 1

The beginning

of

and con-

(CD) measurements

the sign of the first optically

magnitude,

point near 208 my, marking

1965, 1966).

for the other sugars in this study.

above 200 mu the CD absorption band attains

region

(ORD) properties

of their configumtions

have now been made on a select group of these sugars. absorption

dispersion

from positive

by an inflection to negative

The shape of the ORD curve in this region

CD band of galactose that, contmry

to appearances,

New York Heart Association

329

shown in figure

1. The CD

the inflection

point at

BIOCHEMICAL

Vol. 30, No. 4, 1968

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

-0.5

-lOi

190

200 WAVELENGTH

Figure

( mpc)

1. Circular dichroism spactm for D-gluccee (curve A) and D-galactose (curve 5) in water. The original spectra from the recorder charts of the Durrum-Jasco CD spectrophotometer are reproduced. The measurements were made on 0.11 M sugar solutions after mutarotational equilibrium was attained. A cell of 1 mm. optical path length was ed. The CD absorption, Ae, was D where AD is the circular dichroic calculated from the relationship As = ifc)ta optical density, C is the concentmtion rn gm. moles per liter, and d is the light path in cm.

208 mP is not the first peak of a positive negative

Cotton

Cotton

effect,

effect trough at shorter wavelengths

but instead

(Listowsky

et -- ol.,

The CD curves for methyl a- and methyl 8-D-glucopymnoside similar

in magnitude

pymnoside

(Table

the sign of optical

figumtion

at the anomeric configumtion

In the spectral of the pymnoid absorption

rotation

are negative

(Table

is influenced

to o significant

carbon atom (Listowsky

does not determine region

or fumnoid

of the hydroxyl

below

et -- al.,

to a

1965).

are both positive

The CD curves for methyl a- and methyl

and 6-deoxy-D-galactcse

Although

anomeric

I).

is an approach

and

B-D-golocto-

I), but differ in magnitude. extent

by the con-

1965), it is evident

that the

the sign of the first CD band.

200 rry, the fint

forms ore approached

absorption (Ffckett et -- al.,

groups at shorter wavelengths

330

bands of the ring oxygen

(Harrison

1951) followed et VWal.,

1959).

by the It has

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS

Vol. 30, No. 4, 1968

TABLE I Par Ultraviolet Circular Dichroic and Optical Rototory Dispersion Properties of Selected Mono- and Disaccharides 8 CE

Compound

10m2 deg.cm2 190 decimole

Methyl a-D-glucopymnoside Methyl 8-D-glucopymnoside Methyl a-D-galactopymnoside Methyl 8-D-galactopymnoside a-D-glucopymnosyl a-D-glucopymnoside 4-O-a-D-glucopymnoyl-D-glucose 4-O-B-D-glucopymnosyl-D-glucose 4-O-8-D-galactopymnosyl-D-glucose 4-O-8-D-goloctopymnosyl-D-fructose 6-Deoxy-D-galactose D -Monnose Methyl a-D-mannopymnoside D-Talose

(‘) Rotational Direction at 190 mu (2)

+ 2.0 + 2.0 - 0.7 - 6.6 + 3.3 + 0.7 + 2.6 - 7.2 - 7.0 - 5.2 +12.0 + 5.6 + 0.9

(3 Leve I (+) (3) t-1 1 6 t-1 (G (+I (-)(3)

(1) Molar ellipticities were calculated from the from &to previously reported (2) Rotational England et al., 1966). (3) Because Gf ?he overriding rotatory contribution of the a-anomeric form, the ORD curve for methyl a-D-golactopymnoside continues in the positive direction below 200 mp; nonetheless the slope is much sholluwer than the slope of the curve for methyl a-Dglucopymnoside. The ORD curve for D-tolcee exhibits an inflection point at 208 mu and change in direction of rotation (from positive to negative), due to the predominance of the B-anomeric form of this sugar at equilibrium. In geneml, the ORD data express the contributions of all of the asymmetric centers, whereas the CD data ore more limited, therefore the sign of the CD band and the direction of rotation do not always correspond to each other.

therefore oxygen

been postulated determines

(Listowsky rotating

et -- al.,

that the stereochemical

the chamcteristics 1965).

hydroxymethyl

of groups about the ring active

of the configumtion

absorption

region.

introduces

o new axis of polorizability substituents

In addition, difference

on axial

hydmxyl

in the molecule

the ORD

group at C-4

because of the

at C-4 and C-2 (OH and H, respectively).

331

band

at C-4 on the freely

group at C-5 was cited as a major factor determining

in the far ultmviolet

of the axial

of the first optically

Th e influence

properties

dissimilarity

alignment

The

BIOCHEMICAL

Vol. 30, No. 4, 1968

opposite

signs of the CD bands for the sugars in the D-galactcse

those for the glucose

derivatives

can be attributed

The CD data for the disaccharides propcsal

a negative

positive

band.

positive

curves.

positive

CD bands of gmater

Furthermore,

Similarly,

Thus, D-mannose

D-talose,

directions,

Detailed

analysis

for study of specific

asymmetric

of the CD properties

of individual

stereochemical

to the CD spectrum

be possible

alignments below

(Table

I) exhibit

gluccse

which

derivatives.

contribute

in

CD curve. empirical

and conformation,

optically

guidelines

and to define

for the obsenred

from combinations

of various

group

groups at C-Z should exhibit

substituents

responsible

in an ORD study resulting

hydroxyl

group at C-4 gives a

of sugars may provide

transition(s)

It may therefore

hydroxyl

C-2 and C-4 axial

a very weak positive

active

hydroxyl

than those of the corresponding

centers and contributions

in a CD study.

analysis

intensity

of an axial

a-D-mannopymnoside

aspects of sugar configuration

nature of the optically The restrictions

and methyl

containing

exhibits

the presence

axial

to

I, agree with the general

CD band, and an equatorial

sugars containing

series as compared

to these factors.

shown in Table

that, for sugars in the Cl conformation,

at C-4 determines

opposite

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

CD band below

of the contributions active

transitions

to isolate and accumtely

the 200 mu.

of various

are not inherent

assess the contributions

of atoms or groups in the sugar molecule

by the

200 rnt

Acknowledament We are indebted for permitting National

to Dr. V. Toome at Hoffmann

us to use the Durrum-Jasco

Institutes

of Health

(Grant

LaRoche

spectropolarimeter

GM-04428)

for support

Inc.,

Nutley,

in his labomtory,

New Jersey and to the

of this work.

REFERENCES Res., 2, 380 (1966). Englard, S., Avigad, G *I and Listowsky, I., Carbohydrate Harrison, A.J., Cederholm, B.J., and Tenvilliger, M.A., J. Chem. Phys., 33 355 (1959). Listowsky, I ., Englard, S ., and Avigad, G., Carbohydmte Res., 2, 261 (1966). Listowsky, I., Avigad, G., and Englard, S., J. Am. Chem. Sot., 8L 1765 (1965). Pace, N., Tanford,C.,and Davidson, E.A., J. Am. Chem. Sot., 8h 3160 (1964). Pickett, L,W., Hoeflich, N.J., and Liu, TX., J. Am. Chem. Soc.,a 4865 (1951). 332