Jotwtd qf Chrontmogrqdy, 572 (199 I) 5 I-58 Bionmfid Applicnritv~~ Elscvier Science Publishers B.V., Amsterdam CHROM BiO. 6087 Peptide mapping through the coupling of capillary electrophoresis and high-performance liquid chromatography: map prediction of the tryptic digest of myoglobin MASSIMO CASTAGNOLA*. LOREDANA CASSIANO, RITA RABIN0 and DIANA VALERIA ROSSETTI FRANCESCO ANDREASI BASS1 hriruto di Fish, Fucoitir rfi Mcrlicim E Cltirurgia “A. Gctwfli”. Lhiwrsirri Cattolica. Large F. Vito 1. 00169 Rorm (IrtrlQ) (First received May 8th. 1991; revised manuscript received July 30th, 1991) ABSTRACT The tryptic map of horse myoglobin was analyscd through capillary elcctrophorcsis using capillaries modified by a monolayer OF acrylamide. The results were reproducible and the map was obtained in less than 30 min from ca. 8 pmol of cryptic digest. The pcptidc identification was performed using peptides previously identified by high-performance Iiquid chromatography. The peak areas measured using the two techniques are closely related, and the comparison of c!ution and migration times shows that the two techniques provide different maps. Furthermore, using the semicmpirical relationship suggested by Gross- man et al. [Anal. Biochem., 179 (1989) 281, which links the electrophoretic mobility to the charge of the peptide and its number of amino acids, a good agreement between predicted a nd cxperimrntal mobilities was observed. INTRODUCTION Peptide mapping after selective endoprotease digestion plays a central role in any protein sequence analysis; it is the first step in any strategy for a sequence. In addition, by comparative anaIysis it allows information to be, obtained about protein variants and post-translational protein modifications. Furthermore, a good correspondence between experimental and predicted selective endoprotease mapping might be used as a control of genetic engineering peptide products. Because of its high sensitivity and high resolving power, we use capillary eIec- trophoresis (CE) for the analysis of tryptic mapping. Moreover, using a semi- empirical relationship between peptide charge and dimension and its mobility, similar to that proposed by Grossman ef al. [I], a satisfactory agreement between 037%434719 1/%03.50 0 1991 Elsevier Science Publishers B.V. All rights reserved