A statherin and calcium enriched layer at the air interface of human parotid saliva.

TY - JOUR

T1 - A statherin and calcium enriched layer at the air interface of human parotid saliva.

AU - Proctor, Gordon B

AU - Hamdan, Sawsan

AU - Carpenter, Guy H

AU - Wilde, Peter

PY - 2005/7/1

Y1 - 2005/7/1

N2 - Parotid saliva placed in 35 mm diameter tissue culture dishes developed increasing surface viscoelasticity at the interface with air. A surface layer became visible with time and was collected and analysed by protein electrophoresis that indicated a single protein (pI = 4.2; molecular mass = 6 kDa) predominated. Western blot analysis demonstrated that the major protein band reacted with an anti-serum directed against the C-terminal of the calcium-binding salivary protein statherin. Matrix-assisted laser desorption time-of-flight analysis gave a molecular weight of 5380 Da for the protein, corresponding to the molecular weight of statherin. Staining of film protein in electrophoresis gels was compared with statherin synthesized on a solid-phase and the mean statherin content of film formed from 1 ml of parotid saliva was measured as 7 nmol. The mean calcium content of the surface layer was 250 nmol. Surface rheology was greatly reduced in the presence of EDTA whereas surface tension of saliva was unaffected by calcium chelation suggesting that protein accumulated at the surface was unaffected. The results suggest that a layer rich in statherin forms at the interface of saliva and air and that the surface rheology developed is dependent upon protein interactions mediated by calcium. The surface layer may enhance the function of saliva as a protective layer on the mucosal surfaces and teeth.

AB - Parotid saliva placed in 35 mm diameter tissue culture dishes developed increasing surface viscoelasticity at the interface with air. A surface layer became visible with time and was collected and analysed by protein electrophoresis that indicated a single protein (pI = 4.2; molecular mass = 6 kDa) predominated. Western blot analysis demonstrated that the major protein band reacted with an anti-serum directed against the C-terminal of the calcium-binding salivary protein statherin. Matrix-assisted laser desorption time-of-flight analysis gave a molecular weight of 5380 Da for the protein, corresponding to the molecular weight of statherin. Staining of film protein in electrophoresis gels was compared with statherin synthesized on a solid-phase and the mean statherin content of film formed from 1 ml of parotid saliva was measured as 7 nmol. The mean calcium content of the surface layer was 250 nmol. Surface rheology was greatly reduced in the presence of EDTA whereas surface tension of saliva was unaffected by calcium chelation suggesting that protein accumulated at the surface was unaffected. The results suggest that a layer rich in statherin forms at the interface of saliva and air and that the surface rheology developed is dependent upon protein interactions mediated by calcium. The surface layer may enhance the function of saliva as a protective layer on the mucosal surfaces and teeth.

U2 - 10.1042/BJ20042012

DO - 10.1042/BJ20042012

M3 - Article

VL - 389

SP - 111

EP - 116

JO - THE BIOCHEMICAL JOURNAL

JF - THE BIOCHEMICAL JOURNAL

IS - 1

ER -