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Kinetics of histatin proteolysis in whole saliva and the effect on bioactive domains with metal‐binding, antifungal, and wound‐healing properties
Author(s) -
Xiuli Sun,
Erdjan Salih,
Oppenheim Frank G.,
Helmerhorst Eva J.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.09-131045
Subject(s) - saliva , chemistry , proteolysis , biochemistry , electrospray ionization , enzyme , tandem mass spectrometry , chromatography , mass spectrometry
The present study was undertaken to investigate the rate and mode of degradation of individual histatin proteins in whole saliva to establish the impact on its functional domains. Pure synthetic histatins 1, 3, and 5 were incubated with whole saliva supernatant as the enzyme source, and peptides in the resultant digests were separated by reverse‐phase‐ HPLC and structurally characterized by electrospray ionization‐tandem mass spectrometry. The overall V max /K m ratios, a measure of proteolytic efficiency, were on the order of histatin‐5 > histatin‐3 > hista‐ tin‐1. Mathematical models predict that histatins 1, 3, and 5 levels in whole saliva stabilize at 5.1, 1.9, and 1.2 μM, representing 59, 27, and 11% of glandular histatins 1, 3, and 5 levels, respectively. Monitoring of the appearance and disappearance of histatin fragments yielded the identification of the first targeted enzymatic cleavage sites as K 13 and K 17 in histatin 1, R 22 , Y 24 , and R 25 in histatin 3, and Y 10 , K 11 , R 12 , K 13 , H 15 , E 16 , K 17 , and H 18 in histatin 5. The data indicate that metal‐binding, antifungal, and woundhealing domains are largely unaffected by the primary cleavage events in whole saliva, suggesting a sustained functional activity of these proteins in the proteolytic environment of the oral cavity.— Sun, X.,Salih, E., Oppenheim, F. G., Helmerhorst, E. J. Kinetics of histatin proteolysis in whole saliva and the effect on bioactive domains with metal‐binding, antifungal, and wound‐healing properties. FASEB J. 23, 2691–2701 (2009)