An HPLC-ESI-MS analysis of adult human whole saliva evidenced three protein masses (M average 11,487±2, 11,301±2 and 22,362±3Da) eluting in the 32.5-35.0min range. Treatment in reducing conditions allowed establishing that they are S-derivatives of N-terminal acetylated cystatin B, namely its S-glutathionyl, S-cysteinyl and S-S dimer. The identification was confirmed by high resolution HPLC-ESI-MS-MS experiments on the intact naturally occurring proteins and their tryptic digests. S-unmodified cystatin B is rarely detectable in whole saliva of healthy adults (5 subjects out of 65) and its percentage does not overcome approximately 20% of total cystatin B (11±9%). In the majority of subjects (60 out of 65) the mean percentages of the S-modified derivatives were S-glutathionyl 53±13%, S-cysteinyl 15±5%, S-S 2-mer 32±13%. Variations of the percentages of these S-modified derivatives of cystatin B could be indicative of oral oxidative stress. As we are aware, this is the first time that S-glutathionylation and S-cysteinylation were described as extensive PTM of a salivary protein and the first time that these PTMs were detected in naturally occurring cystatin B.

Cabras, T., Manconi, B., Iavarone, F., Fanali, C., Nemolato, S., Fiorita, A., Scarano, E., Passali, G. C., Manni, A., Cordaro, M., Paludetti, G., Faa, G., Messana, I., Castagnola, M., RP-HPLC-ESI-MS evidenced that salivary cystatin B is detectable in adult human whole saliva mostly as S-modified derivatives: S-Glutathionyl, S-cysteinyl and S-S 2-mer, <<JOURNAL OF PROTEOMICS>>, 2012; 75 (3): 908-913. [doi:10.1016/j.jprot.2011.10.006] [http://hdl.handle.net/10807/6076]

RP-HPLC-ESI-MS evidenced that salivary cystatin B is detectable in adult human whole saliva mostly as S-modified derivatives: S-Glutathionyl, S-cysteinyl and S-S 2-mer

Cabras, Tiziana;Manconi, Barbara;Iavarone, Federica;Fanali, Chiara;Fiorita, Antonella;Scarano, Emanuele;Passali, Giulio Cesare;Manni, Armando;Cordaro, Massimo;Paludetti, Gaetano;Messana, Irene;Castagnola, Massimo
2012

Abstract

An HPLC-ESI-MS analysis of adult human whole saliva evidenced three protein masses (M average 11,487±2, 11,301±2 and 22,362±3Da) eluting in the 32.5-35.0min range. Treatment in reducing conditions allowed establishing that they are S-derivatives of N-terminal acetylated cystatin B, namely its S-glutathionyl, S-cysteinyl and S-S dimer. The identification was confirmed by high resolution HPLC-ESI-MS-MS experiments on the intact naturally occurring proteins and their tryptic digests. S-unmodified cystatin B is rarely detectable in whole saliva of healthy adults (5 subjects out of 65) and its percentage does not overcome approximately 20% of total cystatin B (11±9%). In the majority of subjects (60 out of 65) the mean percentages of the S-modified derivatives were S-glutathionyl 53±13%, S-cysteinyl 15±5%, S-S 2-mer 32±13%. Variations of the percentages of these S-modified derivatives of cystatin B could be indicative of oral oxidative stress. As we are aware, this is the first time that S-glutathionylation and S-cysteinylation were described as extensive PTM of a salivary protein and the first time that these PTMs were detected in naturally occurring cystatin B.
Inglese
Cabras, T., Manconi, B., Iavarone, F., Fanali, C., Nemolato, S., Fiorita, A., Scarano, E., Passali, G. C., Manni, A., Cordaro, M., Paludetti, G., Faa, G., Messana, I., Castagnola, M., RP-HPLC-ESI-MS evidenced that salivary cystatin B is detectable in adult human whole saliva mostly as S-modified derivatives: S-Glutathionyl, S-cysteinyl and S-S 2-mer, <<JOURNAL OF PROTEOMICS>>, 2012; 75 (3): 908-913. [doi:10.1016/j.jprot.2011.10.006] [http://hdl.handle.net/10807/6076]
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