ovalbumin and Cataract

Allergic asthma is a chronic inflammatory disease and involves many cells and cellular components. Cataract is a condition that affects the transparency of the lens, which the opacity of the lens caused by any innate or acquired factor degrades its transparency or changes in color. During the establishment of asthma model of rats with chicken ovalbumin nebulization, it was found that asthmatic rats were more likely to have monocular or binocular cataract symptoms than normal rats. Considering that they are all induced by immune imbalance, inflammation, etc., there may be some correlation in the mechanism, and many clues showed that both diseases are associated with activation of the PI3K-AKT-mTOR signaling pathway. Therefore, we hypothesized that the PI3K-AKT-mTOR signaling pathway produces inflammatory or immune imbalance based on allergy leading to cataract.

Topics: Animals; Asthma; Cataract; Disease Models, Animal; Hypersensitivity; Inflammation; Male; Ovalbumin; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Rats; Rats, Wistar; TOR Serine-Threonine Kinases

Large-scale genomics has enabled proteomics by creating sequence infrastructures that can be used with mass spectrometry data to identify proteins. Although protein sequences can be deduced from nucleotide sequences, posttranslational modifications to proteins, in general, cannot. We describe a process for the analysis of posttranslational modifications that is simple, robust, general, and can be applied to complicated protein mixtures. A protein or protein mixture is digested by using three different enzymes: one that cleaves in a site-specific manner and two others that cleave nonspecifically. The mixture of peptides is separated by multidimensional liquid chromatography and analyzed by a tandem mass spectrometer. This approach has been applied to modification analyses of proteins in a simple protein mixture, Cdc2p protein complexes isolated through the use of an affinity tag, and lens tissue from a patient with congenital cataracts. Phosphorylation sites have been detected with known stoichiometry of as low as 10%. Eighteen sites of four different types of modification have been detected on three of the five proteins in a simple mixture, three of which were previously unreported. Three proteins from Cdc2p isolated complexes yielded eight sites containing three different types of modifications. In the lens tissue, 270 proteins were identified, and 11 different crystallins were found to contain a total of 73 sites of modification. Modifications identified in the crystallin proteins included Ser, Thr, and Tyr phosphorylation, Arg and Lys methylation, Lys acetylation, and Met, Tyr, and Trp oxidations. The method presented will be useful in discovering co- and posttranslational modifications of proteins.

Topics: Acetylation; Amino Acid Sequence; Cataract; CDC2 Protein Kinase; Child, Preschool; Crystallins; Humans; Lens, Crystalline; Mass Spectrometry; Methylation; Molecular Sequence Data; Ovalbumin; Oxidation-Reduction; Phosphorylase a; Phosphorylation; Proteome; Schizosaccharomyces

The age-related formation of succinimides in proteins, through spontaneous deamidation of asparagine, and through cyclization of aspartic acid, is thought to be followed by the hydrolysis of the succinimide ring, yielding a mixture of "normal" aspartic acid sites and beta-isomerized aspartic acid sites (isoaspartic acid). The chemical reduction of an isoaspartyl site to the corresponding amino acid alcohol, isohomoserine, has now been investigated as a general approach to measuring the accumulation of isomerized residues in aging proteins. The methods employed were based on conditions previously found to be successful in reducing protein aspartic acid to homoserine. Borane was employed as the reducing agent, and was found to produce the expected amino acid alcohols in reactions with model peptides. In addition, amino acid analysis revealed a complex pattern of unknown products of these reduction reactions, some of which were also evident when a much stronger reducing agent, lithium aluminum hydride, was used. The correlation of some of these side-products with the isomerization of the peptide suggests, unexpectedly, that the reactivity of reducing agents toward aspartyl residues and perhaps other sites in the peptide may be influenced by steric factors related to aspartyl isomerization. The borane reduction method was also applied to proteins. No detectable isohomoserine was formed either in ovalbumin, a model aged protein, or in human lens proteins of advanced age, with conditions that fully reduced normal aspartyl residues to homoserine. These tests thus indicate that the percentage of aspartic acid in the isomerized form in these proteins is below the limit of detectability (below approximately 5%). These results complement previous experimental results that have indicated a low bulk isoaspartyl content in most natural proteins.

Topics: Aluminum Compounds; Amino Acids; Asparagine; Aspartic Acid; Boranes; Cataract; Chymotrypsin; Crystallins; Homoserine; Humans; Indicators and Reagents; Isomerism; Lithium Compounds; Ovalbumin; Proteins; Succinimides; Tetragastrin