title: 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.
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.
authors: Dipartimento di Scienze della Vita e dell'Ambiente, Università di Cagliari, Cagliari, Italy.
authors: Tiziana
authors: T
authors: Cabras
authors: Barbara
authors: B
authors: Manconi
authors: Federica
authors: F
authors: Iavarone
authors: Chiara
authors: C
authors: Fanali
authors: Sonia
authors: S
authors: Nemolato
authors: Antonella
authors: A
authors: Fiorita
authors: Emanuele
authors: E
authors: Scarano
authors: Giulio Cesare
authors: GC
authors: Passali
authors: Armando
authors: A
authors: Manni
authors: Massimo
authors: M
authors: Cordaro
authors: Gaetano
authors: G
authors: Paludetti
authors: Gavino
authors: G
authors: Faa
authors: Irene
authors: I
authors: Messana
authors: Massimo
authors: M
authors: Castagnola
mesh_terms: D000328:Adult; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D055313:Cystatin B / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology*; D046188:Protein Modification, Translational / Q000502:physiology*; D040901:Proteomics / Q000379:methods; D012463:Saliva / Q000737:chemistry / Q000378:metabolism*
chemical_list: C524994:CSTB protein, human; D055313:Cystatin B