Table 1. Unique Autolytic Cuts in the N-Terminal Domain Observed by Mass Spectrometry^a.

		no. of unique cuts		weighted frequency
type (P1)	total no. in the N-domain	incubation for 3 h at 37 °C with 5 mM DTT	incubation for 20 h at 37 °C with 5 mM DTT	incubation for 3 h at 37 °C with 5 mM DTT	incubation for 20 h at 37 °C with 5 mM DTT
C	16	6	7	0.38	0.44
A	19	6	4	0.32	0.21
L	8	4	2	0.50	0.25
Q	7	2	2	0.28	0.29
R	13	2	2	0.15	0.15
T	2	1	1	0.50	0.50
V	9	1	1	0.11	0.11

^aThe position of each autolytic cut was identified by analysis of the generated peptides, and the unique cuts refer to the P1 residue type, looking exclusively at the N-domain (residues 30–157). The weighted frequency = (the number of unique cuts)/(total number in the N-domain).