Freeze-dried plasma proteins are stable at room temperature for at least 1 year

Table 1 The peptide counts to complement C4B protein sequences from correlation analysis of the MS/MS peptides detected in human plasma

Total count	Filter	Gene symbol	MASCOT	OMSSA	X!TANDEM	SEQUEST
972	0	C4B	145	248	311	268
857	1	C4B	145	238	308	166
583	2	C4B	145	119	155	164
		Sum	E-2610	E-2492	E-1129	X_corr 1192

The MS/MS spectra were correlated to charge (z) of 2+ and 3+ with up to three missed cleavages of fully tryptic peptides with precursor ions within ±3 m/z and MS/MS fragments matched within 0.5 Da. The data were filtered by possible charge states (Filter 1) and amino acid sequences (Filter 2) to ensure that only the single best fit of the MS/MS spectra was accepted. The sum p value or X_corr (a function of cross correlation) value for filter 2 is listed. The cumulative p values for all C4B data with filter 2 ranged from E-2492 from OMSSA, E-1129 for X!TANDEM and E-2610 from MASCOT (where E-2 is considered significant) while SEQUEST showed a sum X_Corr of 1192 (where 2.5 to 3.75 is considered significant). The sum total peptide correlation counts from preserved samples, control samples and time course samples from both random sampling and target analysis in this study

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