Relation between structure and the degree of hydration for cobalt(II) bonded to nucleoside 5′-monophosphates

BIOCHEMICAL

Vol. 82, No. 1, 1978

AND BIOPHYSICAL RESEARCH COMMUNICATIONS Pages 92-98

May ?5,1978

RELATIONBETWEEN STRUCTURE AND THEDEGREE OF HYDRATIONFOR COBALT(I1) BONDED TO NIJCLEOSIDE 5'-MONOPHOSPHATES

D.M.L. Goodgame, Chemistry

Yarch

Received

Department,

G.A.

Leach,

Imperial

and 2. Warnke"'

College,

London

SW? 2AY, U.K.

28,1978

SUMMARY: The variation of coordination geometry with degree of hydration has been studied for cobalt(I1) bonded to 5'-AMP, 5'-GMP, 5'-IMP, 5'-UMP, and 5'-CMP. Pink compounds with octahedral coordination about the metal ions were isolated but partial dehydration results in conversion to blue compounds containing tetrahedral cobalt. The ease of conversion is markedly dependent on the identity of the nucleotide. In the case of CoII-5'-AMP warming in water at 34'C is sufficient to cause the change to the tetrahedral form. Spectral results are given and some possible implications to the behaviour of cobalt-containing metalloenzymes, such as Co-RNA polymerase from E. coli, are briefly discussed.

INTRODUCTION: ition

and other

Much of this

from

zinc

that

in

appreciable

of several

solutions

in studies

for

with

geometry.

The metal

-ordinated

(5),

but

five ion

cobalt

[Co(5'-CMP)(HzO)],

' Present

geometry

address:

around

components

the metal

nucleotide is

frequently

RNA polymerase

molecules

the nucleotide

chain

coordination

geometry

completing

structure

is bound is

adopted. in which

trans-

(1,Z). sites

ion,

We have

derivatives

isolated

(3).

We have observed cobalt

an octahedral is also

In contrast,

via

of Chemistry,

ooos-291x/78/0821-0092$oi,oo/o Copyright 0 I978 by Academic Press, Inc. All rights of reproduction in any form reserved.

92

The University,

(4)

to N7

coordination octahedrally

phosphate

5'-CMP ion

binds

forms

cooxygens a

has a tetrahedral

(6).

Institute Poland.

in

used as a replacement

to the metal

the metal

of

of the bonding

[Co,(5'-UMP),(H20)~]10H,0

and a polymeric complex,

coordination

and [CO(~'-IMP)(H~O)~].~H~O

water in

and their

Cobalt

example,

[CO(~'-GMP)(H~O)~]~H~O

of the purine,

acids

cobalt(II)

at pH S7. of,

in the

on the determination

and on the

the structures

interest

to nucleic

has centred

molecules

aqueous

for

is

heavy metals

interest

the biological reported

There

80216

Gdansk,

Vol. 82, No. 1, 1978

This coupled

change with

tetrahedral gate for

&~~HEMI~AL

in geometry

our somewhat geometry

more closely a range

geometry vironment changes substrate

with

AND BI~PHY~ICAL

the lower

unexpected

with

5'-AMP

the relationship

about

a metal

in cell in the

on changing

processes

geometry

might

hydration

observation

between

of the 5'-CMP

that

even in aqueous

of cobalt(II)-ribonucleotide

hydration

of the biological

can adopt

has led

Facile

a

us to investigeometry

changes

of

to a more hydrophobic

to result

molecule

compound

and coordination

a water-rich

be expected

cobalt(I1)

media

compounds. from

RESEARCH COMMUNICATIONS

en-

in accompanying

containing

it

and/or

its

recognition.

mTERIALS AND METHODS: The disodium salts of 5'-AMP (Cambrian), 5'-GMP (Aldrich), 5'-IMP (Sigma), 5'-CMP and 5'-UMP (Koch-Light) and cobalt(I1) nitrate hexahydrate (BDH) were used without further purification. Except where stated solution of the disodium was added, with stirring, 1 mmole) in water (5 ml) case of 5'-AMP and 5'-CMP) 60'~ for 15 mins and then off, washed with a little complex was kept and the 3 hours and then storing the complexes turned from

below, the complexes were prepared as follows : A salt of the nucleotide (1.0 mmole) in water (10 ml) to one of cobalt nitrate hexahydrate (0.291 g, to produce a pink solution (or precipitate in the at pH 6-7. The solution (or mixture) was warmed at cooled to room temperature. The solid was filtered ice-cold water and air dried. One half of the remainder dehydrated by heating to 60°C --in vacua for in a desiccator over silica gel. Upon dehydration, pink to deep blue.

In the case of 5'-AMP, heating the suspension/solution of the pink complex produced a deep blue solid which remained blue on cooling. This was collected and dried as described above. When the reaction mixture was not heated a gelatinous pink solid was obtained, but this lost water so readily on exposure to the air that analyses could not be obtained for the original pink complex, but only for the resultant blue solid. case, cool. large ficient

The Co(5'-CME') complex showed similar the pink colour slowly returned as However, elemental analyses showed quantity of occluded water and even water to cause conversion to the

behaviour on heating but, in this the aqueous mixture was allowed to that the pink solid contained a very air drying was found to remove sufblue form.

Infrared spectra were recorded as Nujol mulls between caesium iodide plates using a Perkin-Elmer 257 spectrophotometer (4000-625 cm-l). Diffuse electronic reflectance spectra were obtained using a Beckmann DK2 spectrophotometer (350-2500 nm) and electron paramagnetic resonance spectra on a Varian El2 e.p.r. spectrometer. Pregl analyses Imperial College.

were

RESULTS AND DISCUSSION:

carried

out

by the Microanalytical

The formulae

and the analytical

93

Laboratory,

results

of the

com-

BIOCHEMICAL

Vol. 82, No. 1, 1978

plexes

we have

were

also

isolated

used to confirm

5'-IMP,

and 5'-UMP.

eotides

and that

those

on which

for

this

X-ray

approach

is

of essentially

as compared

[CO(~'-IMP)(H,O)~]~H~O)

assignments

is

and derived

band energies

these

compounds

The environments tigated

by examining

1% doping)

into

plexes

of 5'-GM?

several

transitions

is

expected

when

suitable

for

spectra

environments. hydrated

II,

given

in Table

of the metal

compounds

are

spectrum results

together

(of for

all

with

the band

ions

in these

compound.

close

gave

e.p.r.

to the g

the effects

compounds

have

eff

the environment

dehydration

the manganese

a tetrahedral

1).

Numerical

geometry results

compounds

were

doped

Manganese(I1)

ions

in

spectra

showing

= 2 region

for

splitting

(Figure are

2).

studies

94

inves-

(nominal

the pink

com-

splitting

of

hyperfine

Such a spectrum

finite

of one N7 of the purine

signals

further

ions

and formation

hyperfine

with

of manganese(I1)

of zero-field

shown by the X-ray

dehydrated

11.

cobalt

and 5'-IMP

partly

in Figure

the host

molecules,

complexes,

also

Co(5'-IMP)H,O

spectra

water

was

the electronic

1 and the numerical

associated

e.p.r.

be the case for

suit-

geometry

particularly

fully

in Table

out,

form

A representative

of the blue,

the

would

Upon partial

are given

their

tetrahedral

the pink,

intensities

of blue are

with

carried

crystalline

about are

nucl-

parameters.

and the high

the spectrum

in

between

shown in Figure

the spectra

(see

be obtained

geometries.

compounds

In contrast,

spectra.

distinction

octahedral

nucleotide

and infrared

ions

three

shown to be the same as

patterns

information

5'-GMP,

these

been

not

of all

were

with

with

had previously

Cobalt(I1)

spectra

compounds

compounds

5'-CMP

experiments

studies

studies,

a clear

in octahedral

The reflectance

the cobalt

could

methods.

as there

of the metal

typical

powder

X-ray

by spectral

with

Thermogravimetric of the

of the pink

structural

the new compounds

1.

contents

complex

X-ray

single-crystal

obtained

in Table

the water

of the blue

of their

Because

given

The samples

full

by comparisons

able

are

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

but unit

small, and five

(4). of the analogous collapsed

to give

blue

tetrahedral

a broad,

as

BIOCHEMICAL

Vol. 82, No. 1, 1978

Table I.

AND BIOPHYSICAL

RESEARCH COMMUNICATIONS

Microanalyses of the Cobalt(II)-Nucleotide % FOUND COLOUR

Co(5'-AMP)H,O Co(5'-CMP) .2H20 Co(5'-GMP).8HzO Co(5'-GMP).2HsO Co(5'-IMP).7HzO Co(5'-IMP).H20 Co(5'-UMP).8H20 Co(5'-UMP).3H20

Table II.

% CALCULATED C H I

C

H

Blue Blue

28.04 25.72

2.88

28.45

3.34

Pink Blue

21.76 27.61

3.92 4.88

25.97 21.29

3.88 5.00

Pink Blue

22.50 28.74

3.97 4.37

26.33 22.61

3.54 4.74

Pink Blue

20.43 24.94

3.21 5.11

28.38 20.58

3.84

24.84

3.10 5.18 3.94

Electronic Reflectance Spectra of the Cobalt(II)-Nucleotide Compounds

Pink (Octahedral) 'T$P)

Complexes

f ?

VJCLEOTIDI

L

Compounds

*g

+ 'Tlg(F)

cm-'

cm-l

5'-AMP

19230

5'-CM!?

19050

15630 15870

5'-GMP 5'-IMP

19230 19610

15870 16260

5'-IJMP

19230

14600

Blue (Tetrahedral)

6850

775 885 0.91

Complexes

NUCLEOTIDE 5'-AMP

17700

6850

5'-CMP 5'-GMP 5'-IMP 5'-UMP

17390 17390

6860 7140 + 7140 7140 +

17390 17860

R

+ Not observed. ' Value only approximate due to the broad nature of the band.

95

Vol. 82, No. 1, 1978

BIOCHEMICAL

AND BIOPHYSICAL

I 20000

I I0000

I 25000

RESEARCH COMMUNICATIONS

I 5000

cm’.’

Figure

1.

relatively

(c)

featureless

- an effect

interactions ions.

results

original

pink

compound

via

version purine

takes

tetrahedral

that

from

N3 and phosphate dehydration form, studied.

place

even

cobalt(II)

which

and the host,

geometry

structure

on removal

has been are

strong

dipolar

paramagnetic

the tetrahedral

the metals

;

indicates

octahedral

structure

in which

Na2(5’-IMP)

a monomeric,

to a polymeric

Such a polymeric

nucleotides

species

a change

compounds

to the blue

ions

therefore,

[Co(5'-CMP)(H20>],

Partial

all

from

molecules.

binding

the manganese(I1)

seems probable,

complexes

water

absorption

between

It

spectra Of: (a) Co(5'-IMP).HzO.

Electronic (reflectance) (b) Co(5'-IMP).7H20;

in the blue

structure

in

the

of some of the

found

linked

cobalt

(6)

for

the blue

by nucleotides

groups.

of the occurs

cobalt(U) very

Indeed in water

derivative

much more readily the formation

on gentle

complexes

of 5'-AMP,

with

96

of the blue,

warming other

than

(I\, 34'C)

and its

with

con-

the other

polymeric whereas

organic or inorganic

virtually

ligands

BIOCHEMICAL

Vol. 82, No. 1, 1978

AND BIOPHYSICAL

RESEARCH COMMUNICATIONS

I mT

440

Figure

are

2.

X-Band e.p.r. spectra (b) Co(Mn)(5'-IMF').H~O (1% nominal Mn doping

relatively

either

unstable

by simple

replacement

Some further suspending

in water

addition

and water

of

-IMP

the pink

cobalt-5'-AMP,

-ca.

to octahedral

or by a combination

(with

3-4 hrs

were

(a)]

species of ligand

to the blue

5'-UMP

ease of dehydration

compounds

as a reasonable

typical for

made of the

cobalt-nucleotide

(chosen

s 5'-CMP

molecules

tests

The ease of conversion

> 5'-GMP

converted

of

addition.

I-methylpentane-2,4-diol onment).

and are

of water

qualitative

samples

ofr (a> Co(W(5'-IMP),7H,O; [instrumental gain 5 x that in each case).

model

at 36'C in

of a non-aqueous

form was:

by

5'-AMp

>> 5'-IJI-ip minutes

conversion

times

of several

and -*ca

1 day for

5'-IMP,

for

envir> 5'for

samples

of

% 30 mg). The spectral complex

biological

and other systems

observations in several

we report respects.

97

here Electronic

have relevance spectroscopy

to more of

BIOCHEMICAL

Vol. 82, No. 1, 1978

the metal enzymes

centres (7)

cobalt

enriched

ogue,

RNA-polymerase both

d(pT)Xo,

but

nucleoside

presumably

coordination

in

from were

shows bands

(8)

cm-'

has been proposed

on enzyme-substrate For example

E. coli

found

of cobalt-containing geometry

such spectra

demonstrated.

the 17,100

in which

metals

structural

or enzyme

the spectrum

at

to be perturbed

~17,100

of

and

by a template

band was influenced

anal-

by the addition

in

the nature

the extent of the

the cobalt-nucleotide

from

octahedral

with

which

these

metalloenzymes.

to tetrahedral coordination Secondly,

and the attendant dependent

tion

conditions.

then

this

ion

process.

might

upon the If well

(Co or 2n in the RNA-polymerase

and functional

to consider

by changes

clearly

only

intrinsic

have

important

geometry

of which

studies

of

triphosphates.

As these

is

changes

have been

cm-'

used in

tetrahedral'

Moreover

interaction

% 14,200

frequently

and a 'nearly

in many cases. -template

has been

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

this provide

roles

to which

in gene

medium.

compounds

we have

on partial changes

could

the potential structural identity selectivity at least

in

also

their

at the metal

unit in

in,

for

geometry the

ease

centres

moiety under

of such

are

given

the biological example,

ACRNOWLEDGEMENTSr We thank the Science Research Council for Studentship (to G.A.L.) and the British Council for a Research 2.W.).

hydrasystem

a recognit-

a Research Scholarship

REFERENCES 1. 2. 3. 4. 5. 6. 7. 8.

Hodgson, D.J. (1977) Progr. Inorg. Chem. 23, 211-254. Marzilli, L.G. (1977) Progr. Inorg. Chem. 23, 255-378. Wu, C-W, Wu, F.Y-H., and Speckhard, D.C. (1977) Biochem. 16, 5449-5454. De Meester, P., Goodgame, D.M.L., Jones, T.J., and Skapski, A.C. (1974) C.R. Acad. SC. Paris, Ser. C, 279, 667-669. Cartwright, B.A., Goodgame, D.M.L., Jeeves, I., and Skapski, A.C. (1977) Biochim. Biophys. Acta 477, 195-198. Clark, G.R. and Orbell, J.D. (1975) J.C.S. Chem. Commun. 697-698. Lindskog, S. (1970) Struct. Bonding (Berlin) 8, 153-196, and refs therein. Speckhard, D.C., Wu, F-Y-H., and Wu, C-W. (1977) Biochem. 16, 5228-5234. 98

way

in coordination

the organic

prevails

one factor

facile

demonstrates

the nucleotide

it

be influenced

change

such changes

changes of

studied

occur

for

will

(3)

The particularly

dehydration

above)

transcription

such processes

solvation

quoted

(to