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Table 2 Identification of signature peptide sequences of STC1-HT for the assignment of the intra- and intermolecular disulfide bonds.

From: Low-resolution structural studies of human Stanniocalcin-1

   

Mass

Disulfide Bond

Sequence of peptides

Protease

Theoretical

Observed (Expected)

    

[M+2H]

[M+3H]

[M+4H]

C45-C59; C54-C74; C65-C114

C45LNSAL...IDC K75

C114STFQR119

Trypsin

3981.51

  

996.22

(996.38)

C54-C74

Q51VGC GAFA57

D72IC KSF77

Chymotrypsin

1389.61

695.95

(695.81)

464.24

(464.21)

 

C65-C114

E61NSTC...GMY71

A110IRRC STF117

Chymotrypsin

2184.89

 

729.36

(729.30)

547.26

(547.23)

C98-C128

C98IANGVTSK106

M120IAE...C YSK131

Trypsin

2318.06

 

773.73

(773.69)

580.56

(580.52)

C98-C128

K97C IA...SKVF108

Q118RMIA...EEC Y129

Chymotrypsin

2761.32

 

921.17

(921.45)

691.14

(691.34)

C135-C170

L132NVC SIAK139

S166LLEC...TIR179

Trypsin

2424.19

 

809.12

(809.07)

607.08

(607.05)

   

Mass

Disulfide Bond

Sequence of peptides

Chemical Reagent

Theoretical

Observed (Expected)

    

[M+H]

C202-C202*

D200HC AQTHPRA209

D200HC AQTHPRA209

Formic acid

2266.98

2268.11

(2267.99)

  1. Samples were digested by trypsin or chymotrypsin with or without dithiotreitol and iodoacetamide, separated by UPLC and analyzed by ESI-QTOF; or digested with formic acid and analyzed by MALDI-QTOF. The presented mass is the monoisotopic. Dimer disulphide bond is indicated by asterisk (*) [see Additional file 1, 2 and 3].