Transaminases in the acquired pellicle

Objective: Transaminases (AST, aspartate amino transferase; ALT, alanine amino transferase) are relevant enzymes in physiology and pathology of the human organism. The aim of the present in situ study was to demonstrate the presence of these enzymes in the enamel pellicle. Methods: Bovine enamel slabs were fixed on buccal sites of individual upper jaw splints and worn for 3, 30 and 120 min by 5 subjects to allow pellicle formation. The in situ pellicles were tested for AST and ALT. Enzyme activities were measured photometrically via determination of the products pyruvate and oxalacetate using lactate-dehydrogenase and malate-dehydrogenase, respectively. Results: Enzymatic AST- as well as ALT-activities are present in the acquired pellicle within 3 min. The enzyme activities exposed at the pellicles' surfaces increased slightly with the pellicle formation time (ANOVA, AST: n.s., ALT: p = 0.021). However, the two enzymes show considerable intraindividual and interindividual variability. The mean AST-activity of the pellicle amounted to 1.07 +/- 0.81 mU/cm(2) (ALT 1.18 +/- 0.52 mU/cm(2)). The ALT-activity of the centrifuged saliva was 26.62 +/- 11.09 mU/ml (AST 35.98 +/- 29.35 mU/ml). Conclusions: AST as well as ALT are present in the in situ pellicle layer and may contribute to the intrinsic maturation of pellicle proteins. (C) 2009 Elsevier Ltd. All rights reserved.