Table 2.

Summary of identified peptides from elastase proteolytic processing of PGRN

	Peptide	Sequence location	QS	SEQUEST XCorr	Mascot Ion Score	Δ mass (ppm)
(i) LDKWPTLSRHLG (Linker P – G)
EL-1	LDKWPT	45–50	2	1.33	29	−0.58
EL-2	TLSRHLG	51–57	2	1.43	24	−0.62
(ii) KLPAHTV (Linker B – A)
EL-3	KLPAHTV	273–279	2	1.42	29	−0.33
(iii) PWMEKAPAHLSLPDPQAL (Linker A – C)
EL-4	PWMEKAPA	343–350	2	1.73	23	0.55
EL-5	PWM(ox)EKA	343–348	2	1.37	28	−1.70
EL-6	AHLSLPDPQ	350–358	2	1.93	23	−0.57
EL-7	HLSLPDPQAL	351–360	2	3.22	70	1.3
EL-8	HLSLPDPQA	351–359	2	1.81	36	1.2
EL-9	HLSLPDPQ	351–358	2	1.97	38	0.79
EL-10	HLSLPDP	351–357	2	1.61	40	−1.3
EL-11	HLSLP	351–355	1	1.34	23	1.0
EL-12	LSLPDPQ	352–358	1	1.75	35	0.23
(iv) VAGLEKMPA (Linker (Linker C – D)
EL-13	VAGLEKM(ox)PA	423–431	2	1.41	32	0.79
(v) TFLARSPHVGV (Linker D – E)
EL-14	TFLARSPHV	506–514	2	1.89	34	0.53
EL-15	RSPHVGV	510–516	2	1.82	33	−0.24
(vi) RWDAPLRDPAL (Linker C-terminus end)
EL-16	RWDAPLRDPAL	579–589	2	2.55	21	−0.19
EL-17	RWDAPLRDPA	579–588	3	2.94	50	2.0
EL-18	RWDAPLRDP	579–587	2	2.38	24	0.52
EL-19	RWDAPLR	579–585	2	1.98	26	−1.1

QS: Charge state, M(ox) methionine oxidation, Δ mass (ppm), difference between experimental and theoretical masses in parts-per-million. Annotated MS/MS spectra of the identified granulin peptides generated by elastase activity were included in Additional file 1: Figure S2, numbered from EL-1 to EL-19