A polyacrylamide-gel electrophoretic study of human tear proteins

Abstract

The protein composition of normal and pathological tears was studied by polyacrylamide-gel (disc) electrophoresis. Polyacrylamide-gel electrophoresis was shown to detect at least 14 fractions in 2-10 microliters of native tears. A comparison was made between the protein composition of normal tears and serum. The most characteristic bands in the tear-protein pattern were identified by parallel electrophoresis of tears, serum, human milk and purified egg-white lysozyme. The identified fractions were specific tear prealbumin, serum albumin, transferrin, lactoferrin and lysozyme. An unidentified major tear-protein component was also described. The tear-protein pattern was divided into six zones: (1) prealbumin zone; (2) post-albumin zone; (3) post-transferrin zone; (4) macroglobulin zone; (5) basic globulin zone; (6) prelactoferrin zone. A significant rise in the level of serum albumin and transferrin was demonstrated in tears from cases of acute catarrhal conjunctivitis. The optimal circumstances were discussed under which major and minor tear components and basic and acidic tear proteins can be determined simultaneously. Polyacrylamide-gel electrophoresis is recommended as a useful method to study the various diseases of the anterior segment of the eye.

Effect of smoking on tear proteins

“…In further studies, differences in tear protein patterns of diabetic patients were demonstrated by two-dimensional electrophoresis [15]. In other studies, electrophoretic characteristics of different tear proteins were investigated [3,7] and autoantibodies were found that support the hypothesis of an underlying autoimmune mechanism in dry-eye disease [13].…”

Critical role of mass spectrometry proteomics in tear biomarker discovery for multifactorial ocular diseases (Review)

“…In 1974, LTF and LYZ were found to be the major protein constituents in tear fluid (47). Using 1DGE, scientists found serum albumin (ALB) and transferrin were significantly elevated in the tear fluid of eyes even in mild cases of acute catarrhal conjunctivitis (48). Using 2DGE, scientists found lower abundance of proteins in human reflex tears, including CST4, cystatin SN and α-2-glycoprotein, in addition to the previously reported LTF and LYZ (49), in particular, high expression of PRR4 in reflex tears (50).…”

Quantification of tear proteins by SDS-PAGE with an internal standard protein: A new method with special reference to small volume tears

“…The advantages of this technique remain in the fact that it allows visualization of the whole tear protein profile, is capable of analyzing several tear samples in one experiment, and requires a minimal amount of sample volume. According to previous studies, whole tear sample separated by SDS-PAGE gel yielded a defined profile of 7-10 major tear protein bands [16][17][18][19][20]; in addition, as little as 20 ng/band could be visualized by this procedure [21,22]. Accordingly, proteins above 100 μg/ml in tear samples may be visualized on SDS-PAGE from as little as 0.2 μl tear volume loaded.…”