‘Plastoquinone B’ — Some structural studies

Vol. 25, No. 6, 1966

BIOCHEMICAL

'Plastoquinone

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

B'

- Some

Structural

Studies

by W.

T.

Griffiths*,

Department

of

Biochemistry,

Liverpool

Received

November

A total

lipids.

as

Plastoquinone is

side

chain

while

PQ-4 1963)

(Misiti

et

Crane,

* Present Bristol

al.

and

these

compounds

an

plant has

been

dimethyl-p-benzoquinone.

first

the

quinone

-5

to

in

be

isolated

plants

position

has

(Trenner

a C20

spinach

leaves

side

has

(1965).

address: 8, U.K.

unknown

a Cl5

and

an et

chain

FQ-4

(Kegel

or et

structure IQ-9

the

infrared, al.

1962,

isoprenoid

al.,

1959)

(Eck

and

side

chain

and

chromato-

3545

cm

and

showed

which

is

absent

been

described

Henninger

spectra p&C!'

(1965) -1

have

al.,

absorption

et at

spectra

PQ-3, PQD

in

Threlfall

or

of

ultraviolet

however

PQ-4

Mass

from

play

from

of

leavesbms

from PQC

region

PQ-3,

in

to

isolated

distributed

plastoquinones

The

by

et

PQ-3

three

thought

1965).

1964). similar

widely

are

been

2:3

the

horsechestnut

PQB,

frequency

Das

units

distinct

isolated

of

C5

other

designated

PQ-9)

nine

and

graphically

or be

al.,

Three

of

to

from

Trebst,

of

isoprenologues

known

of

have

structure

A (PQA now

Liverpool,

U.K.

which

photosynthesis

chemical

established

which

plastoquinones

in

The

are

six

role

of

2, 1966

of

important

3,

University

of PQD'

a band from

and

all

these

("= PQC in

and

the

and O-H

the

infrared

been

reported

by

peak

M at

quinones PQD)

as

stretching spectra

m-9. for

PQB, For

PQB

Department

PQC

and

P&D have

a molecular

of

Biochemistry,

596

ion

University

m/e

746

of

was

Bristol,

found

BIOCHEMICAL

Vol. 25, No. 6, 1966

while

p&C and PQD both

cases

at m/e 189.

fragmentation similar

These

patterns

isoprene

Recent

1966)

Pennock,

to PQB could into

six

from

an additional from

similar

IQ-Bl;

-B2;

study

and this

type

compounds

of the IQ-B infrared

Young elder IQ-B

material

petroleum coated

plates

(paraffin

Ultraviolet All

of lithium

nig.ra)

fraction

six

were

isolated

of

obtained

distinct

in PQ

were

were

(Griffiths

Kieselgur

used as a source extract 1966)

The 3% diethyl to adsorption

each of which chromatoplates

by ether/light

T.L.C. ether

(Kieselgel

in light

on partition developed

with

597

gave ultraviolet

G

petroleum). T.L.C.

Spectra and ethanol

of the

of the leaf

two IQ-B's.

in cyclohexane

and the

of IQ-B's

et al.,

12% di-iso-propyl -

eluted

hydride

are described.

from a lipid

on alumina.

with

yielded

aluminium

(T.L.C.)

leaves

was treated

developed

the samples

were

A quinone

into

PQ

-C ; -C ; -C ; -C5 and -C 1 2 3 4 6 some recent findings on the properties

described

and Infrared

These

to FQC and IQD was also

Chromatography

These

impregnated

polarity

and fractionated

of some of the samples

fraction

in acetone)

-B5 and -B . 6

The effect

(Sambucus

PQ-B fractions

of similar

the characteristic

be fractionated

gives

of the lipid

(E/P)

showing

and

as IQ-C,;

as previously

chromatography

Three

also

Layer

samples.

of plants

-B4;

report

and Thin

fraction

-B3;

could

the

FQC and PQD could

Wallwork

'A max. 255 and 263 w.

and mass spectra

Isolation

a variety

in

FQB.

a quinone

properties

samples.

while

i.e.

described

The present

ring

WB is

probably

(Griffiths,

components

chromatographic

this

that

quinone

absorption

designated

the quinone

from

in all

structurally

unsaturation

laboratory

be isolated

that

p&A or hydrated

this

base peaks

and the mass spectrometry

to the suggestion

has indicated

distinct

ultraviolet

water

led

as hydroxylated work

at m/e 764 with

findings

residue

be considered

six

had peaks

to P&A but with

second

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

2.5%

Vol. 25, No. 6, 1966

BIOCHEMICAL

absorption

spectra

-ca.263

w

sodium

borohydride,

with

identical

232 and 276 q

maxima at 255 w

with

PgA.

as with

by all raised

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

free

films

spectra between

samples,

FQ-B 2, is

basically

to that

and C-O-C stretch (CH2 rocking Such bands

at

in ethanol

with

On reduction

FQA, isobestic

samples

(fig.

points

Spectra

ot

salt

reproduced

plates. in

of a chain are normally

at

PQBZ

were

recorded

The spectrum

fig.

of P&A but with respectively

obtained

(milliiuons)

of the preparations rock

were

1).

and RedwzedOS)

V#xdelergth

Infrared

and inflexions

2.

This

bands

of an ester

grouping)

groups

found

associated

ldrared

Spam

598

with of FQ-82

of one of the

spectrum

additional

of methylene

as solvent-

is

similar

at 1730,

1253

and 722 cm-1

-(CH2)nfatty

(GO

where acid

n -S 4).

esters.

Vol. 25, No. 6, 1966

BIOCHEMICAL

The infrared suggesting

spectra

It

purification

the other

of an ester

the presence

preparations.

failed

of all

the presence

alternatively

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

should

to remove

grouping

of an ester

the ester

in

were

similar

these

compounds

contaminant(s)

be mentioned

of the preparations

P&-B's

at this

stage

by adsorption

absorption

in

the

that

repeated

and partition

bands

from

or

T.L.C.

the infrared

spectra

of the samples. Mass Spectra

and Effect

To check

the possibility

the mass spectra Organic

of three

Chemistry

of the samples

This

acid

could

residue

corresponding

(256).

by Das --et al.

1965)

of CH3(CH2)14COOH]. was observed

P&-B5 and IQ-B6,

described

for

1965).

aluminium

occurs

showed

a

at m/e 189,

examined

peak at m/e 746 [loss

as the

'molecular

of the PQB preparation

gave essentially

plus

in PQ 3

a strong

The mass spectra

taken

hydride/ether

peak'

of Das and

of the other

the same picture

by lml.

At the end of this addition

The mixtures

were

then

to dryness.

in view

up in 5 ml.

solution

followed

the dropwise

and taken

A (748)

P&-B3 and P&-B4

separately

of effervescence minute.

to plastoquinone

peak

samples as that

PC-B,.

Plastoquinone-B1, were

on the A.E.I. a molecular

peak described

in the mass spectrum

examined,

results

also

esters

at the

the PQA, P&B, PQC and P&D samples

A similar

(Das et al.,

University,

C12H1302,also

PQ-B,

coworkers

determined

The base peak observed

and in

(1965).

being

of P&-B2 showed

correspond

to the formula

et al.,

Hydride,

were

Liverpool

The mass spectrum

at m/e 1,002.

(Misiti

Aluminium

of the PC-B preparations

Department,

MS9 instrument.

palmitic

of Lithium

period

of ethanol extracted

diethyl

(10 mg./ml.) excess

followed

The product

added

reagent

ether,

and lithium

till

cessation

to stand

for

was destroyed

by ice-cold

so obtained

599

ether

and allowed

excess

with

of the mass spectrometry

washed from

one by

O.lN H2S04. with

water,

dried

the PQ-Blsample

Vol. 25, No. 6, 1966

BIOCHEMICAL

was chromatographed grade

III

on alumina

and eluted

following

order:

with

but region

in

instead

is

material

to Brockmann

(E/P)

mixtures

in the

migrated

elutes

solid

the PQ-B's

transparent

under

in

the ultraviolet

a peak in the O-H stretching major

peaks

of a saturated

with

a similar

primary

Rf to cetyl plates

frequency

-1 1050 cm-1 and 722 cm .

at

aliphatic

Kieselgur

these

alcohol

alcohol. during

developed

with

30%

in acetone.

typical

FXJ spectrum

infrared

this

that

reported

from

the infrared

PQ-C's

of p&A in

gel

which

(1965)

migrated

differing in the

material

developed

with

previously

this

In

with

of a band

Furthermore,

the

at 263~.

was identical

--et al.

G chromatoplates

in benzene

showed

and an inflexion

the possession

cm -1 .

at-3545

described

with

when 10%

an Rf of the same order

(Griffiths

et al.,

as

1966).

and Discussion

The results the proposal

of the experiments

that

some plants

to be fatty

The fact

that

identified

proposal

at 255~

the ultraviolet

gave a spectrum

on silica ether

Conclusions

in

PQC' and PQD' by Threlfall

region

di-iso-propyl

appear

withAmax.

spectrum

chromatographed

the polar

when examined

material

for

O-H stretching

been

a white

typical

The 25% E/P fraction

the

normally

on paraffin-impregnated

water

water

petroleum

cm -1 and two other

at-3450

T.L.C.

which

the infrared

Such a spectrum This

with

100% P; 5% E/P and 25% E/P.

contained

showing

deactivated

ether/light

The 5% E/P fraction conditions

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

since

hydrolysis be esterified plastoquinone-B

six

acid

in plants these

contain

esters

distinct

type

six

(hydroxy)

(Griffiths

PQ-B's

thereby

compounds.

600

1966)

as arising

have led all

would from

compound(s).

(Pg-C's)

have

strengthen

this

the esters

hydroxyplastoquinones

giving

to

of which

A type

plastoquinones

of the six acid

here

distinct

et al.,

may be considered

a fatty

briefly

of a hydroxy-plastoquinone

polar

or.alternatively,each with

reported

the corresponding

by may six

BIOCHEMICAL

Vol. 25, No. 6, 1966

The identification 'PQB'

on adsorption

a higher less

of

polar

than

(Threlfall

on partition

residue

character

It results

in

so that

chromatographed is

also

phase

it

'PQB'

preparation.

'PQB'

possible

these

from (1965)

molecule

by this

of palmitic

Furthermore,

acid

in

the extent

that

the light their

(Personal

renders

it

a highly

from

communication

than

the long

chain

phase when

for

the parent

ion

ester

peak - at of a

(1,002). of their our

a molecular

from Professor

'PQB'

by the loss

has confirmed

possessed

the

of their

as the molecular

of our results also

more polar

to reconcile

by Das and coworkers

sample

adsorption

lipophilic

stationary

can be accounted

(256)

a reinvestigation

preparation

During

conclusions

appears

Rf than PQA

on the mass spectrometry

group

with

chromatography

chromatography

The mass peak - described

why

PQA (migrates

1966).

the paraffinic solvent.

explains

a lower

upon it

in an aqueous

m/e 746 observed

1,002.

in

partition

favours

of Das --et al

with

et al.,

confers

than

and paper

migrates

grouping

on reversed

acid

more polar

Henninger

the ester

B' as esters

T.L.C.

again

1965,

et al.,

PQA whereas fatty

appears

PQA i.e.

chromatography

'plastoquinone

T.L.C.

Rf) while

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

'PQB' findings

ion

E. Lederer

to

at m/e to Professor

R. A. Morton.) The demonstration

of the occurrence

plastoquinones

&Q-B's)

related

of six

series

the complex function

nature

characterised

and the possibility hydroxyplastoquinones

of the problem

or a chemical

structure

plastoquinones.

at a more complete and at demonstrating

in plants

chemical

(IQ-C's)

the hitherto

characterisation relationships

and the PQ-C's.

601

of a

serves

to illustrate

upon a biochemical

Work is at present

any structural

esterified

of the existence

of deciding for

of six

incompletely in progress

aimed

of the plastoquinones-B between

the PQ-B's

Vol. 25, No. 6, 1966

BIOCHEMICAL

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

Acknowledgements The author Pennock

for

their

thanks advice

Professor

R. A. Morton,

and encouragement

F.R.S.,

during

this

and Dr.

J. F.

work.

References C. and Lederer, E., Biochem. Biophys. B.C., Lounasama, M., Tendille, Res. Commun., 2l, 318 (1965) Eck, H. and Trebst, A., Z.Naturforsch., 2, 446 (1963) Griffiths, W. T., Wallwork, J. C. and Pennock, J. F., Nature, 211, 1037 (1966) Henninger, M. D. and Crane, F. L., Plant Physiol., 39, 598 (1964). Henninger, M. D., Barr, R. and Crane, F. L., Plant Physiol., 41, 696 (1966) Kegel, L. P., Henninger, M. D. and Crane, F. L., Biochem. Biophys. Res. Commun., 8, 294 (1962) Misiti, D., Moore, H. W. and Folkers, K., J.Am.Chem. Sot., 87, 1402 (1965) Threlfall, D. R., Griffiths, W. T. and Goodwin, T. W., Biochim. Biophys. Acta, 102, 614 (1965) Trenner, N.R., Arison, B. H., Erickson, R. E., Shunk, C. H., Wolf, D.E. and Folkers, K., J.Am.Chem.Soc., 8l, 2026 (1959). Das,

602