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This Article Full Text Free Full Text (PDF) Free All Versions of this Article: fj.09-131045v1 fj.09-131045v2 23/8/2691    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Sun, X. Articles by Helmerhorst, E. J. Search for Related Content PubMed PubMed Citation Articles by Sun, X. Articles by Helmerhorst, E. J.

Kinetics of histatin proteolysis in whole saliva and the effect on bioactive domains with metal-binding, antifungal, and wound-healing properties

Department of Periodontology and Oral Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, USA

¹ Correspondence: Boston University, Goldman School of Dental Medicine, Dept. of Periodontology and Oral Biology, Goldman School of Dental Medicine, Boston University, Boston, MA 02118, USA. E-mail: helmer{at}bu.edu

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 > histatin-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 K¹³ and K¹⁷ in histatin 1, R²², Y²⁴, and R²⁵ in histatin 3, and Y¹⁰, K¹¹, R¹², K¹³, H¹⁵, E¹⁶, K¹⁷, and H¹⁸ in histatin 5. The data indicate that metal-binding, antifungal, and wound-healing 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.

Key Words: oral • proteolytic • enzymes • proteins • proteomics