Studies on the water-soluble lens proteins of vertebrates with particular reference to low molecular weight fractions

Distribution and pattern of water-soluble proteins of lens as revealed by gel filtration chromatography in fish (Catla catla) of different age groups

The water soluble proteins of the lens collected from different age group of the fish Catla catla were subjected to Sephadex G 200 gel filtration to fractionate and to characterize the protein and further to determine the elution volume (Ve) of different fractions. The relative proportion of each fraction was also calculated. Total number of fractions F1 to F4 was discernible through gel filtration. The molecular weight of these varied from 35,000 Da to 640,000 Da. Three subfractions were also noted in F1 fraction. Interesting observations were, presence of alpha, betaH betaL crystallins in all age groups and LMW proteins in older age group. a-crystallin present in major amounts in comparison to betaH & betaL crystallins. Decrease of alpha-crystallins (except in age group II) with the increase of age, counter balanced by the increase of betaH crystallins. Increase of betaH crystallins was followed by the decrease of betaL crystallins. Results suggest that proportionate distribution of different classes of proteins determined by column chromatography is widely variable.

Eye lens regeneration and the crystallins in the adult newt, Notophthalmus viridescens

Upon lens removal, the adult Eastern Spotted newt, Notophthalmus viridescens, has the capacity to regenerate an ocular lens. Crystallins, proteins characteristic of the vertebrate lens, were studied from normal and 3-month regenerated adult newt lenses. When separated by high-performance liquid chromatography (HPLC) or Sephadex G-200SF column chromatography, the crystallins from normal and regenerated lenses were fractionated into what appear to be the classical four groups: alpha, beta High, beta Low, and gamma. Upon further examination by immunoelectrophoresis, the first peak contains both alpha and beta crystallins. This study provides evidence that most of the crystallins from the regenerated lenses share biochemical properties with those of the normal lens crystallins based on their native molecular weight, isoelectric point, and the molecular wt of their constituent polypeptides, indicating that the fidelity of gene expression in reactivated iris tissue is high. Some differences are found between normal and regenerated lens crystallins and are most obvious in the beta-crystallin region: the proportion of beta crystallins is decreased in regenerated lenses when the total proteins are fractionated by column chromatography and some of the beta-crystallin polypeptide chains found in normal lenses are missing from regenerated lenses. Iris epithelial cells are normally withdrawn from the cell cycle and are synthesizing a tissue-specific product, melanin. After lentectomy these cells dedifferentiate, redifferentiate into lens cells, and their progeny then synthesize different tissue-specific proteins, crystallins. Little is known about the specific mechanism(s) for the activation of gene expression in eukaryotes, but the regenerating lens suggests itself as a good model in which to study this biological problem.

Comparative and age-dependent aspects of crystallin size and distribution in human, rabbit, bovine, rat, chicken, duck, frog and dogfish lenses

Lens extracts obtained from eight vertebrate species were analyzed using high-performance gel permeation chromatography with differential refractive index and low-angle laser light scattering detection. The elution patterns enabled the direct determination of the proportions of the crystallin classes as well as the molecular weights of the numerous size fractions in a more rapid and accurate way than previously. Concerning the mammalian species, also age-dependent aspects could be assessed by comparing the data obtained from the extracts of differently aged lenses and/or lens parts.

Studies on the water-soluble lens proteins of the lizard, Calotes versicolor. II. Electrophoretic and immunological characterization

The Sephadex G-200 gel filtration fractions C1 to C6 of the water-soluble lens proteins of Calotes versicolor have been characterized by polyacrylamide gel electrophoresis (PAGE), 7 M urea PAGE, SDS PAGE, and immunological tests. C1 fraction, an alpha-crystallin which cross-reacts with chick alpha, has very low amount of B chains. It shows two bands in SDS PAGE, one strong and another weak. C2 and C3 fractions, both of which partially cross-react with chick beta-crystallins, are largely similar but not identical. C2 in SDS PAGE produces a faint band with a molecular weight of 54,500, which suggests that C2 may either contain a small amount of delta-crystallin in addition to beta H crystallin or that Calotes beta H has a high molecular weight subunit like human beta H; however, in immunological tests no material cross-reacting with chick delta was seen. C4 and C5 are low molecular weight, monomeric, and basic proteins which in all probability are not gamma-crystallins.