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Ben J. Glasgow, Gary Marshall, Oktay K. Gasymov, Adil R. Abduragimov, Taleh N. Yusifov, Charles M. Knobler; Tear LipocalinsPotential Lipid Scavengers for the Corneal Surface. Invest. Ophthalmol. Vis. Sci. 1999;40(13):3100-3107. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
purpose. To investigate the dynamic effect of tear lipocalins (TLs), the major
lipid-binding protein in tears, at aqueous–cornea and lipid–aqueous
interfaces, and their potential contribution to surface tension in the
methods. Human apo- and holo-TLs were applied to the aqueous subphase in a
Langmuir trough, and changes in surface pressure were measured. Changes
in the contact angle of tear components were observed on Teflon and
ferric-stearate–treated surfaces. A nitroxide-labeled derivative of
lauric acid and a fluorescence-labeled derivative of palmitic acid were
used to monitor the dynamic interaction of lipid removed from a
hydrophobic surface by the major tear components in solution.
results. TLs increase the surface pressure at the aqueous–air interface
by penetrating, spreading, and rearranging on the surface. Apo-TLs show
a longer diffusion-dependent induction time than holo-TLs due to more
extensive oligomerization of the apoprotein. Kinetic analysis of
relaxation time suggests that apo-TLs have more rapid surface
penetration and rearrangement than holo-TLs, indicative of a more
flexible structure in apo-TLs. TLs reduce the contact angle of
solutions on lipid films, a property that is greater with TLs than
other tear proteins. TLs, unlike lysozyme and lactoferrin, remove
labeled lipids from hydrophobic surfaces and deliver them into
conclusions. TLs are potent lipid-binding proteins that increase the surface
pressure of aqueous solutions while scavenging lipids from hydrophobic
surfaces and delivering them to the aqueous phase of tears. These data
suggest important functional roles for TLs in maintaining the integrity
of the tear film.
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