Sequence analysis of microgram amounts of peptides by mass spectrometry

246

SHOH’I‘

~‘~l~l~l1’SI~‘.\‘I‘IOSS

with 6 grn of Hyflosu~~rcc~l is usually Micicrit for one 3 rug s:arnl)lc of RKA. An RXA smnple was isolated from SrrI~ro~~eZla t!/pil.i adapting the proccdurc of Hiatt (a), while isolation of the RKA from bacteriophage f4 has been drscribctl (3). The results of thcb malysia of these two san~plrs of RSA using the moclificcl ,1IAK prorc~lurc arc1 pr(~s(~nte(l in Figure I.

Sequence

Analysis

of Microgram by Mass

Amounts

of

Peptides

Spectrometryl

The t’echnique of perrnethylation which has been applied to peptidcs by Lederer and his colleagues (l-8; see reference 5 for review) has opened the way for the routine use of mass qmtrornetry in sequence analysis. This procedure, when applied to an acyl:ttctl pq)title, results in quantitative mrthylation of ln5mary antI scc~~ritlary amiclc nitrogens, and carbosyl, hytlrosyl, mid inii~lazole groups. The rcsnlting peptidr clrriratircs possess the dual advantage of greatly enhanced volatility and, usually, rather simple ni:Iss spcct~ra which arise mainly from splitting at ’ This work 08748 from tlrr

was supportd 1,~ grants HII-00674. National Institutrs of Hrnkh.

HE-04762.

.ZM-12397,

and

CA1-

288

,SHORT

AcMeAla-

1OOr

MeLeu

COXI~II’SICATIOS,5

Me3 Gin -MeAla*

M

128

425 255

801

397

AcMe,

100

Lys(Acl~Me,Glu~MeThr(-CH30H~

349 I

Effect

of Glycerol of

on Lowry Protein

and

Determination

Biuret

Methods