TABLE 3.

Mass spectrometry analysis of IC-regulated proteins observed either by 1D or 2D gel electrophoresis

Proteina	Genea	Spotb	Gel type	Protein characteristicc		Mass spectrometry valued			Air/IC ratio (P)f
				pI	MM (Da)	Error (ppm)	Coverage (%)	Score
Carbamoyl phosphate synthase (large subunit)	pyrAb1	1	1D	4.93	115,757	20	46	484	-
		2	1D	4.93	115,757	22	56	429	-
		5	1D	4.93	115,757	25	47	305	-
		1	2D	4.93	115,757	31	42	334	4.7 (1.5)
		2	2D	4.93	115,757	42	54	371	4.7 (1.5)
		3	2D	4.93	115,757	42	56	458	4.7 (1.5)
Dihydroorotase	pyrC	4	2D	5.76	45,677	40	52	123	4.3 (1.9)
		5	2D	5.76	45,677	44	64	130	4.3 (1.9)
Carbamoyl phosphate synthase (small subunit)	pyrAa1	6	2D	5.67	40,143	49	48	212	2.5 (1.8)
Aspartate carbamoyltransferase	pyrB	7	2D	6.06	34,689	50	63	189	5.4 (2.2)
		8	2D	6.06	34,689	38	62	205	5.4 (2.2)
Dihydroorotate dehydrogenase	pyrD	9	2D	6.14	31,318	51	53	139	5.5 (2.6)
Orotate phosphoribosyltransferase	pyrE	10	2D	5.64	22,691	50	72	147	3.3 (3.4)
Transcriptional repressor	pyrR1	11	2D	5.64	19,812	NDe	71	127	2.0 (1.6)

^aEMBL accession no. Z54240.

^bFor 1D gels, numbers refer to growth conditions (1, no IC added; 2, with arginine; 5, addition of 2g KHCO₃/liter), and for 2D gels, numbers refer to spots shown in Fig. 3.

^cpI, Isoelectric point; MM, molecular mass.

^dScore, probability-based Mowse score calculated using MASCOT software (Matrix Science, London, United Kingdom); error, mass accuracy; coverage, percentage of the protein sequence covered by the matched peptide.

^eInternal calibration not determined.

^fP values were determined by Student's t test. -, results are shown in Fig. 2.