Fast atom bombardment mass spectrometry of human proinsulin

Vol. 110, No. 3, 1983 February

BIOCHEMICAL

AND BIOPHYSICAL

RESEARCH COMMUNICATIONS

Pages 753-757

10, 1983

FAST ATOM BOMBARDMENT MASS SPECTROMETRY OF HUMAN PROINSULIN Michael

Barber,

Robert S. Bordoli, Gerard Nicholas J. Horoch

J.

Department of Chemistry, of Manchester Institute of Science Sackville Street,Manchester M60 l&D

University

and Brian Tudor

Road

Elliott,

and Technology, , U.K.

N. Green,

V.G. Analytical Limited, , Altrincham , Cheshire WA14 5RZ , U.K.

Received December 7, 1982

SUMMARY: The observation human proinsulin obtained is reported.

Hitherto,

the

of protonated by fast atom

classical

methods

mass spectrometric

analysis

before

which

ionization,

approximately

1500 5,

(1)

and plasma

the

latter

low flux coincidence

source

the

resolution recently

has not developed

has sufficient

mass analysers.

limited

useful

range

over

(2)

have been used above

which

mass

unit

been used

to

mass range

atom

to permit These

range

which

the

have higher

with

753

and

this

a

While

m/z

1000. ion

conventional

mass resolution

is traditionally

mass resolution

limit

However,

(FAB)

use of

desorption

there

is

of such a system,

above

bombardment

to

a derivatised

successfully

of mass analysis.

fast

this

u (3).

method the

Field

and ionize ca 7000

for

mass range

a few curiosities.

been demonstrated

intensity

or-panic

attainable

but

weight

limit

compounds volatilization

all

has only

upper

sample

the

to volatilize

time-of-flight

no theoretical mass

for

of molecular

ion

organic

have required

desorption

oligonucleotide

of ionizing

has limited

has been used

molecular species from bombardment mass spectrometry

defined

In

unit contrast

source

(4)

scanning but

a

as the

is maintained. 0006-291X/83/030753-05$01.50/0 Copyright 0 1983 by Academic Press, Inc. AI1 rights of reproduction in any form reserved.

Vol. 110, No. 3, 1983

Using

a FAB ion

magnetic to

BIOCHEMKAL

source

sector

observe

fully

resolved

species

(2846 u),

and less

with

mass spectra

well

reported

the

resolved

oxidized

measurements

to delineate

we have

to study

molecules

this

short

unresolved our

knowledge,

molecule

an upper able atoms,

at plasma

acquired of

sensitive support

The atom

discharge

paper.

considerably With invariably corresponds

system

current obtained

in

form

mass range

of

MM ZAB-HF

ions

by the

maximum

magnetic

was operated

At an ion

up to m/z 3200 LI,

using

flux

attain-

8 keV xenon

of l-2

mA. The data were of 100 2 min -1 with a span using

was mounted ion

source

ion

mass range 154

energy, for

steel

at room temperature.

over maximum

ultra-violet

on a stainless

glycerol,

lifetime

instrumentation, at maximum

to

biological

source.

oscillographically

spectral

of the

which,

Analytical

FAB ion

at a rate

the

detection

transmit

The sample

to a minimum

the

will

currents

in

weights.

natural

a V.G.

source

FAB ion

mass spectrometry.

used was acidified

enhanced

hormone

molecular

to report

a standard

scanning

and was examined

The solvent

(3455 2) .

to use the

underivatised

were recorded

chart

glucagon

of human proinsulin,

instrument

by magnetic

300 2. Data

species

determined

).

(5)

melittin

from

useful

possible

we wish

with

this

mass limit

(m/zocH2/V

it

observed

fitted

of 8 keV,

the

were made using

mass spectrometer

peptide

insulin

even higher

largest

has been

Measurements

energy

with

ion

is the

which

protonated

(5731 2) (6) which

insulin

now found

communication

molecular

ability

mass spectrometers.

However, source In

sector

the

on adrenocorticotropic

part

magnetic

containing

of bovine

bovine

current

performance

(M + H)+ species

B chain

designed

a high

bee-venom

ACTH (4535 u) and complete of a project

RESEARCH COMMUNlCAT0NS

we have demonstrated

(M + H)+ from

2) and the

We have also

conJunction

mass spectrometer,

molecular

(3482

in

AND BIOPHYSICAL

which other

systems

sensitivity which

a particular

gave a tried. is

unfortunately magnetic

Vol. 110, No. 3, 1983

field

strength.

Since

on instrument between been

with

with

were fully

order

ion

to 2.7

together

with

a reduction

is

with

energy the

is

the

molecular ordinarily region

source ions

communication,

the

protonated

needed

to be

sensitivity

from

the

overall

seen from

for

the

would

sample,required

instrument

the

figure

molecular

abundance

the

parent that

insulin, of only

isotope

that

species

the (M + H)+

Thus, identification

even

if

great

At low masses as the

atoms

even with

monoisotopic

species

protonated

up the

respect

isotopes

molecule.

molecular

distribution.

monoisotopic

largest

of the

making

shown that

the

weights

ceases

to be the

Indeed

we have

(M + H)+ species to

Consequently

the

largest

for

peak

proinsulin

has an in

the

the

exacerbated. the

of the least,

the

isotope

distribution.

resolved

species,composed

for

the

a fully

be assigned

ca 15% with

is further

information

monoisotopic

in

peak

say the

in

current

be acquired.

largest

situation

reduction

weight

as 3000 2 this

parent

in this

mass spectrometer

ion

readily

of as little

intensity

presented

of the

we have previously

shown with

data

to increase

it

which

ion

of 8 keV to be focused.

low intrinsic

greatest

However,

molecular

unresolved.

ion

the

protonated

permitted

The concomitant

parent

molecular

the

magnet

for

would

in the

has already

field

keV.

To obtain

ion

effect

use of a high

distribution

spectrum

This

made

in

voltage

Thus

off

improvements

in resolution

completely

(5) where

a trade

dependent

after

to acquire

the

transmission.

is always

is strongly

only

accelerating

reduced

RESEARCH COMMUNICATIONS

power

power.

melittin

2846 11 and an ion

In

isotope

there

resolved

and the

m/z

mass resolving

and resolving

illustrated

brightness

the

AND BIOPHYSICAL

transmission,

sensitivity

species

the

BIOCHEMICAL

parent

ion

monoisotopic

region

were fully

(Iv! + H)+ ion without

difficulties, 755

would

studying

resolved, present, model

to

compounds.

Vol. 110, No. 3, 1983

BIOCHEMICAL

HUMAN

AND BIOPHYSICAL ,

PROINSULIN

’ ,

C6,~H6)aN,,b0127s6. Ion Energy

RESEARCH COMMUNICATIONS

MH+ 93a9.7

i 2.7 kV. :

It

is,however,

chemical the

possible

molecular

elements

measuring

weight

comprising the

figure.

the

molecular

using

based the

caesium

weight

weipht

of protonated

empirical

formula

shown in

bombardment size

results ion

not source

and complexity,

information

only

the

may be deduced

parent

weights

ion

method,

a of

by region

measured

proinsulin

to be 9390 g chemical

is 9389.7

u based

on the

1.

demonstrate

the

ability

of the

and ionize

show that from

atomic

The theoretical

proinsulin

data

can be achieved

above

of protonated

to volatilize but

presented

chemical

unresolved

using

figure

the

This

as a reference.

molecular

These

on the

of the

Ide have,

iodide

from

molecule.

mass centroid

shown in the chemical

to measure

meaningful

unresolved 756

molecules molecular

data.

fast

atom

of this weight

Vol. 110, No. 3, 1983

BIOCHEMICAL

AND BIOPHYSICAL

RESEARCH COMMUNICATIONS

ACKNOWLEDGMENTS The U.M.I.S.T. support

authors

of this

The au+,hors

sre

wish

to thank

the

S.E.R.C.

for

financial

project. indebted

to Eli

Lilly

& Co. for

supplying

the

sample. REFERENCES

1. H,D. Beckey, 'Principles of Field Ionisation and Field Desorption Mass Spectrometry', Pergamon, Oxford, 1977. 2. R.D. Macfarlane

and D.F. Torgerson,

3. C.J, McNeal, Anal.

Science,

1976,

'IJ'l,

Chem., 1982, 24, 43A.

R,D. Sedgwick and A.N, Tyler, 4. M. Barber, R,S, Bordoli, J. Chem. Sot. Chem. Commun., 1981, 325. 5. M. Barber, R.S. Bordoli, R.D. Sedgwick, A.N. Tyler, G.V, Garner, D.B. Gordon, L.W. Tetler and R.C. Hider, Biomed. Mass Spectrom., 1982, 2, 265. 6. M. Barber, R.S. Bordoli, G.J. Elliott, R.D. Sedgwick, A.N. Tyler and B.N. Green, J. Chem. Sot. Chem. Commun., 1982, 936.

757

920.