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Query: UMLS:C0272170 (SDS)
 50,377 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The high molecular weight aggregates (HMWA) obtained from normal and cataractous human lens nuclei have been resolved by SDS-polyacrylamide gel electrophoresis, and the alpha crystallin band has been probed with antisera made against the whole alpha crystallin molecule and with antisera made against synthetic peptides of alpha crystallin (alpha A2 147-161 and alpha A2 163-173). Quantitation of these antisera binding demonstrated that the anti-alpha A2 163-173 serum and the anti-alpha whole sera bound equally well to the alpha crystallin band from the HMWA fraction from normal and cataractous lenses. In contrast, the anti-alpha A2 147-161 serum bound little, if at all, to alpha crystallin from normal lenses, while it bound well to alpha crystallin from cataractous lenses. These results demonstrate a covalent alteration in the alpha crystallin molecule, and suggest a possible location of a covalent change that may occur during the cataractogenic process in the aged human lens.
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PMID:Covalent change in alpha crystallin during human senile cataractogenesis. 334 73

Mammalian lenses contain multiple gamma-crystallin gene products, which are differentially synthesized during lens development. We now report the isolation and characterization of multiple gamma-crystallins from lenses of adult spiny dogfish (Squalus acanthias) aged about 20-30 years. About 50% of total lens protein solubilized in 50 mM phosphate, pH 7.0; about 25% of this soluble fraction consists of gamma-crystallins as determined by gel filtration. These gamma-crystallins appear homogeneous with respect to molecular weight (approximately equal to 20,000) on SDS-polyacrylamide gels, but their isoelectric points range from below pH 6 to above 10. Preparative cation-exchange chromatography on SP-Sephadex at pH 4.8 resolves four major subfractions, while anion-exchange on DEAE-cellulose at pH 9.5 resolves seven subfractions. Although these procedures separate basic from acidic polypeptides, most of these gamma-crystallin subfractions still consist of polypeptide mixtures, as determined by ion-exchange HPLC and isoelectric focusing. Analytical cation-exchange HPLC on SynChropak CM300 at pH 6.0 resolves at least 10 different gamma-crystallin components. Amino acid compositions of all the subfractions are similar, yet distinct in the sense that three subclasses can be distinguished. Sulfhydryl residues range from three to six per chain, most of which are buried. The large heterogeneity of gamma-crystallins in adult lens may result from different gene products in combination with post-translational modification.
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PMID:Heterogeneity of gamma-crystallins from spiny dogfish (Squalus acanthias) eye lens. 334 35

Lens crystallins were isolated from the homogenates of reptilian eye lenses derived from three different species by gel-permeation chromatography and characterized by gel electrophoresis, amino-acid analysis, N-terminal sequence analysis and circular dichroism. Four fractions corresponding to alpha-, delta/epsilon/beta-, beta- and gamma-crystallins were obtained for the crystallins from caiman lenses, whereas delta- and gamma-crystallin fraction were present in lesser amounts or missing in the turtle and snake lenses, respectively. The native molecular masses for these purified fractions and their polypeptide compositions were determined by gel filtration and SDS-gel electrophoresis, respectively, revealing the typical subunit compositions for each classified crystallin. The spectra of circular dichroism indicate a predominant beta-sheet structure in alpha-, beta- and gamma-crystallins, and a major contribution of alpha-helical structure in delta/epsilon-crystallin fraction, which bears a resemblance to the secondary structure of delta-crystallin from the chicken lenses. Comparison of the amino-acid contents of each orthologous class of reptilian crystallins with those of evolutionary distant species still exhibited similarity in their amino-acid compositions. N-terminal sequence analysis of the crystallin fractions revealed that all fractions except that of gamma-crystallin are N-terminally blocked. Extensive sequence similarity between the reptilian gamma-crystallin polypeptides and those from other vertebrate species were found, which establish the close relatedness of gamma-crystallins amongst the major classes of vertebrates.
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PMID:Biochemical comparison of lens crystallins from three reptilian species. 338 68

Transdifferentiated embryonic quail neuroretina cells synthesize in vitro crystallins (the lens-specific proteins) and form lentoid bodies (structures that mimic lens fiber cells) which also contain crystallins. A comparative study on the size of crystallins is reported in 7-day-old embryonic quail lenses, in 7-day-old embryonic quail transdifferentiated neuroretina cells (normal and MH2 transformed), and in isolated lentoid bodies. Analyses are performed using Superose FPLC in combination with SDS-PAGE and Western blot procedures. In quail lenses, an apparent 560-580-kDa alpha crystallin homopolymer is found and delta crystallin, the major avian lens protein, is detected as a 180-kDa tetramer. beta Crystallins, present in low amount within the 180-kDa peak, are a heterogeneous population composed of subunits of molecular weight identical to those found in chick lenses. In addition, an apparent 46-kDa monomeric delta crystallin is found. Normal and MH2-transformed neuroretina cultures produce an alpha crystallin polymer of lower molecular weight (450 kDa) and delta crystallin in a monomeric or dimeric form. The Western blot pattern of beta crystallins from MH2-transformed neuroretina cultures is strictly identical to that of quail lens beta crystallins. In particular, the beta B1 crystallin, which is specific to lens fiber cell differentiation, and the major beta 25-kDa crystallin are present. However, analysis of isolated lentoid bodies from normal transdifferentiated quail neuroretina cultures showed alpha and delta crystallins of comparable size to those found in lens extract, in particular the delta crystallin in tetrameric form. The lentoid body lens-like structure could favour the crystallin aggregation process.
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PMID:Transdifferentiated embryonic neuroretina cells: an in vitro system to study crystallin aggregation process. 342 6

A biochemical comparison has been made on the crystallins isolated from duck and frog lenses. Gel-permeation chromatography of lens homogenates from both classes on Fractogel TSK HW-55(S) revealed a homogeneous trimeric protein of 120 kDa in the duck lenses and a monomeric protein of 39 kDa in the frog lenses. Both crystallin fractions consist only of an approx. 38-kDa polypeptide in their subunit structures as determined by SDS gel electrophoresis. These two crystallins were compared with respect to their native molecular masses, subunit structures, peptide mapping and amino acid compositions in order to establish the identity of each crystallin. We have found differences in the protein structures of these two crystallins despite some degree of similarity in their amino acid compositions.
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PMID:Biochemical comparison of epsilon [correction of gamma]-crystallins from duck and frog eye lenses. 348 58

A systematic biochemical comparison has been made of the crystallins isolated from the lenses of five different species belonging to the five major classes of vertebrates. Gel-permeation chromatography of the lens homogenates on Fractogel TSK HW-55(S) revealed well-defined elution patterns with a characteristic distribution of different classes of crystallins from each species. SDS gel electrophoresis and statistical comparison of the amino acid contents indicated that all crystallin groups from different classes share some common subunits and similarity in their amino acid compositions. The results coupled with the relatedness shown in the amino acid compositions of fish gamma-crystallin with those of mammalian gamma-crystallin and the squid crystallin from the invertebrate pointed to the possibility of the existence of a common ancestral protein for all crystallins. This is in favor of the divergent rather than convergent evolution of lens crystallins as commonly assumed in the literature.
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PMID:Phylogenetic comparison of lens crystallins from the vertebrate and invertebrate--convergent or divergent evolution? 348 83

Lens crystallins were isolated from the homogenate of frog (Rana catesbeiana) eye lenses by gel permeation chromatography and characterized by gel electrophoresis, amino acid analysis and circular dichroism. Four well-defined fractions corresponding to alpha/beta-, beta-, frog 39.5 kDa and gamma-crystallins comprising the relative weight percentages in the total soluble cytoplasmic proteins of 18%, 15%, 14% and 48% respectively were obtained. The native molecular masses for each purified fraction were determined to be 432, 207, 40 and 23 kDa, respectively. The polypeptide compositions as determined by SDS-gel electrophoresis revealed the typical subunit structures of mammalian crystallins with the exception of 39.5 kDa monomeric crystallin, which has not been shown in other classes of vertebrate lenses. The spectra of circular dichroism indicate a predominant beta-sheet structure in all four fractions, which also bears a resemblance to the secondary structure of mammalian crystallins. Comparison of the amino acid compositions of frog crystallins with those of mammalian and fish crystallins suggests that gamma-crystallin from the frog is more closely related to that of porcine than fish crystallins, and the frog 39.5 kDa, frog beta- and lamprey 48 kDa crystallins are probably mutually interrelated.
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PMID:Biochemical characterization of crystallins from frog lenses. 349 2

Lens crystallins were isolated from homogenates of reptilian eye lenses (Caiman crocodylus apaporiensis) by gel-permeation chromatography and characterized by gel electrophoresis, and amino acid and N-terminal sequence analyses. Four fractions corresponding to alpha-, delta/epsilon/beta-, beta- and gamma-crystallins were identified on the basis of their electrophoretic patterns as revealed by SDS gel electrophoresis. Comparison of the amino acid contents of reptilian crystallins with those of mammals suggests that each orthologous class of crystallins from the evolutionarily distant species still exhibits similarity in their amino acid compositions and probably sequence homology as well. All fractions except that of gamma-crystallin were found to be N-terminally blocked. N-terminal sequence analysis of the purified gamma-crystallin subfractions showed extensive homology between the reptilian gamma-crystallin polypeptides themselves and also those from other vertebrate species, suggesting the existence of a multigene family and their close relatedness to gamma-crystallins of other vertebrates.
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PMID:Sequence comparison of gamma-crystallins from the reptilian and other vertebrate species. 362 58

Because of minimal or no turnover, lens proteins are subjected to substantial post-translational modifications which in turn disrupt lens architecture and change the optical properties leading to senile cataract formation. Progressive glycation is believed to have the potential to initiate the changes that are conducive to lens opacification. Fisher 344 rats were systematically followed from juvenile to older and aged phases of their life to study the relationship between lens glycation and high molecular weight (HMW) aggregate formation as well as quantitative and qualitative changes in lens crystallins. Levels of glycated proteins were quantified by affinity chromatography. Changes in lens crystallin composition and HMW aggregate formation were monitored by molecular sieve HPLC, further confirmed by SDS-PAGE and IEF techniques. As the age advances HMW and insoluble proteins increase with a concomitant disappearance of gamma-crystallins from soluble fraction. This disappearance of gamma-crystallins coincided with increased glycation (approximately 2-fold higher in insoluble fraction) and decreased sulfhydryl groups from soluble fraction. It appears that lens protein glycation, disappearance of gamma-crystallins and sulfhydryls from soluble fraction and increase of insoluble fraction and HMW aggregate are interrelated.
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PMID:Lens protein composition, glycation and high molecular weight aggregation in aging rats. 365 42

Crystallins from carp eye lenses have been isolated and characterized by gel permeation chromatography, SDS-gel electrophoresis, immunodiffusion and amino acid analysis. gamma-Crystallin is the most abundant class of crystallins and constitutes over 55% of the total lens cytoplasmic proteins. It is immunologically distinct from the alpha- and beta-crystallins isolated from the same lens and its antiserum shows a very weak cross-reaction to total pig lens antigens. Comparison of the amino acid compositions of carp gamma-crystallin with those of bovine gamma-II, haddock gamma- and squid crystallins indicates that gamma-crystallin from the carp is very closely related to that of the haddock, and probably also related to the invertebrate squid crystallin. In vitro translation of total mRNAs isolated from carp lenses confirms the predominant existence of gamma-crystallin. The genomic characterization of carp crystallin genes should provide some insight into the mechanism of crystallin evolution in general.
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PMID:Characterization of lens crystallins and their mRNA from the carp lenses. 370 73


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