Protective effects of carnosine on dehydroascorbate-induced structural alteration and opacity of lens crystallins
: important implications of carnosine pleiotropic functions to combat cataractogenesis.
Monnier, "Aging of long-lived proteins: extracellular matrix (collagens, elastins, proteoglycans) and lens crystallins
," Comprehensive Physiology, 2011.
Lens transparency is maintained by water soluble proteins classified into ubiquitous (a, b and g crystallin) and taxon-specific lens crystallins. Ubiquitous crystallins show great diversity among vertebrates and invertebrates due to selective pressure leading to adaptive conflict.
Major taxon-specific lens crystallins in birds and reptiles are e-crystallin and d-crystallin (de Jong et al., 1981).
Evolution of eye lens crystallins: the stress connection.
We have identified aA-, bA2-, bA4-, bB2-and bB3-crystallins as ubiquitous crystallins and d-, t-crystallins as taxon-specific lens crystallins in water soluble fraction.
Taxon specific lens crystallins, however, were evolved after ubiquitous group and are recruited from metabolic enzymes in response of environmental stress (Wistow, 1993).
The exact mechanism for diabetic cataractogenesis is still not understood but high levels of plasma glucose that allow glucose molecules to enter the lens independently are thought to be a major risk factor, leading to oxidative stress, formation of Schiff's base (a nonenzymatic reaction of glucose with residual primary amino groups of lens crystallins), and an accumulation of advanced glycation end products leading to yellow discoloration/browning of the lens .
Samples of lens crystallins without copper (II) were used as control.
In all cases the ELISA technique was carried out in an indirect configuration and using a secondary antibody-alkaline phosphatase conjugate since these were the basic conditions providing best sensitivity and consistency of results previously found in ELISAs designed to measure lens crystallins in our laboratory (12).
Antibodies to Lens Crystallins after Endocapsular Cataract Surgery.
PURPOSE: Senile cataracts are associated with oxidation, fragmentation, cross-linking, insolubilization, and yellow pigmentation of lens crystallins
. This process is partially explained by advanced glycation end products (AGEs) from ascorbic acid (ASA), as the authors unequivocally demonstrated in an hSVCT2 transgenic mouse.