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Soluble proteins of individual human normal and nuclear cataractous lenses of 60-70-year-old subjects were collected for this investigation. The average wet weights of both the normal and nuclear cataractous lenses were found to be essentially identical, approximately 230 mg. When the lens proteins, either cortical or nuclear, were subjected to fractionation by Sephadex G-200 sf chromatography, six fractions (F-I to F-VI) were obtained and their respective molecular weights approximated. F-I, which contains alpha-crystallin and high molecular weight aggregates, was subsequently fractionated through a series of Bio-gel A chromatographic columns. The quantities of the proteins and the molecular weights of each fraction were obtained. All the proteins fractionated were subjected to SDS gel electrophoresis by which the molecular weights of the subunits were obtained. The distribution and molecular weights of proteins smaller than 0.2 X 10(6) showed certain changes, more noticeable in the nucleus than in the cortex, between the normal lens and nuclear cataractous lens. For the high-molecular-weight protein aggregates, the major fraction in the lens cortex was found to be in the 5-1.5 X 10(6) range, representing 10 and 12% of the total protein in the normal and cataractous lenses, respectively. The major fraction in the nucleus was found to be greater than 150 X 10(6), representing 11 and 19% for the normal and cataractous lenses respectively. The above data are presented for the first time to show the differences in distribution of the high-molecular-weight proteins in the cortical and nuclear regions, and their respective changes in cataractogenesis. Based upon these data, we are able to calculate the average molecular weights of (1) the soluble cortical and nuclear proteins and (2) the total soluble protein, in the normal and cataractous human lenses.
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PMID:Characterization of lens proteins. IV. Analysis of soluble high molecular weight protein aggregates in human lenses. 674 24

The ontogeny of alpha-, beta-, and delta-crystallin antigens in the developing lens of mallard (Anas platyrhynchos) was investigated by indirect immunofluorescence using specific antibodies to mallard alpha-, beta-, and delta- crystallins raised in rabbits. The IgG fraction from each antiserum was isolated by affinity chromatography usign Protein A Sepharose CL-4B. Fluoresceinee (FITC) or rhodamine (TRITC) conjugated goat anti rabbit (GAR) gamma-globulin was used as the secondary antibody. The results show that alpha-, beta-, and delta-crystallins appear simultaneously in the developing mallard lens and are detectable from 66 hr (stage 15/16). This situation is different from the chick where delta- is known to appear first followed by beta-, and alpha-. This could be due to species variation. In the epithelium, however, as in the chick, delta- emerges first followed by beta-, and alpha- but rather late when compared with the chick and this seems probably due to a difference in the incubation time between the two species. Results from immunofluorescence and Tris-SDS gel electrophoresis demonstrate that alpha A subunit of the alpha-crystallin appears much earlier than the alpha B subunit. We also found that the newly discovered epsilon-crystallin (18) appears long after the three major crystallin classes.
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PMID:Ontogeny and localization of the alpha-, beta-, and delta- crystallin antigens during lens development in mallard embryos. 676 22

Age-related changes in the bovine lens trypsin inhibitor activity were measured by assaying water soluble extracts of 10 concentric slices from the periphery to the center of the lens. Inhibitor assays were carried out at pH 7.0 and 7.9 using prenatal, calf and mature lenses. The inhibitor at pH 7.0 remained constant throughout the lens but the pH 7.9 activity decreased sharply in the lens nucleus. This was particularly true for the prenatal and calf lenses. Agarose A-15 m gel filtration of the water soluble inhibitor activity showed a decrease in inhibitor in the alpha-crystallin region and a corresponding increase in inhibitor activity in the HMW protein peak. Inhibitor assays were carried out on the water insoluble fractions following solubilization in 6.0 M-urea. Little or no inhibitor activity was seen in the outer cortical fractions but the inner cortex and nucleus contained high levels of inhibitor activity in the water insoluble fraction with specific activities 7- to 10-fold higher than the comparable crude lens extracts. These data suggest that the lens inhibitor activity at pH 7.0 and 7.9 aggregate into a HMW complex and with time preferentially enter the water insoluble fraction. The distribution of a purified 5.5 K inhibitor protein between the water soluble and the water insoluble fraction was measured. In the periphery all of this inhibitor was in the water soluble fraction, but toward the center of the lens this inhibitor began shifting to the water insoluble fraction. Slices taken from the lens nuclear region showed that all the inhibitor was in the water insoluble fraction as detected by both activity measurements and SDS-PAGE.
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PMID:Age-related and distributional changes in the trypsin inhibitor activity of bovine lens. 685 41

The EDTA-extractable proteins (EEP) of calf lens fiber cell membranes have been further characterized. Fiber EEP has been purified by gel filtration and resolved into eight bands with molecular weights of 30-38 K dalton by SDS-polyacrylamide gel electrophoresis. For epithelial EEP the same range has been obtained. In agreement with these findings a value of 33 K has been determined for fiber EEP by Sephadex G200 thin-layer gel filtration, while 34 K dalton was found by high-performance gel permeation chromatography in combination with low-angle laser light scattering (HPGPC-LALLS). The isoelectric focusing patterns of fiber and epithelial EEP show considerable charge heterogeneity. By two-dimensional electrophoresis the relation molecular weight-isoelectric point has been established for most EEP components. Peptide maps of the individual protein bands of fiber EEP differ from each other and from those of the beta Bp-, beta B1a- and beta B1b-crystallin bands, which have about the same molecular weight. From our results we conclude that EEP is not an oligomeric nor a multisubunit protein, but a collection of different extrinsic membrane proteins, biochemically unrelated to lens crystallins. The fact that removal of the cytoskeleton by urea-treatment of the membranes is a prerequisite for its isolation by EDTA or EGTA suggests that EEP is bound to the inner surface of the plasma membranes, probably via calcium.
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PMID:Charge and molecular weight heterogeneity of EDTA-extractable proteins from calf lens membranes. 685 42

Two low molecular weight proteins with isoelectric points above pH 8 occur in the water-soluble proteins of the 24-day-old rat lens. Their molecular weights, estimated by SDS gel electrophoresis, are 9,500 and 10,500 daltons. The 9,500-dalton protein cross-reacts with gamma 1-crystallin. The 10,500-dalton protein designated gamma 3-crystallin is nonidentical with gamma 1 and gamma 2-crystallins and shows no cross-reactivity with alpha- and beta-crystallins.
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PMID:Immunological properties of rat lens gamma-crystallins. II. Characterization of low molecular weight components. 713 24

Relative amounts of two water-soluble beta-crystallin polypeptides with molecular weights of 26,000 (26K) and 28,000 daltons (28K) were measured in a number of species and also in different age groups of rats. The data indicate an age-dependent increase in the quantity of the 26K which is concomitant with a decrease in the 28K polypeptide. The ratio of these two polypeptides in the total water-soluble fraction is similar to that observed in the purified beta-crystallins. Purified beta 3-crystallin of the rabbit and its equivalent "beta L" of the bovine lens display charge heterogeneity upon DEAE chromatography, suggesting subtle qualitative changes in these crystallins. The presence of these two polypeptides in the urea-soluble fraction of lens preparations is also an indication of qualitative changes. The 26K polypeptide of beta-crystallins studied here is different from the 26K main intrinsic membrane protein in that, unlike the latter, it does not aggregate upon heating in SDS-buffer.
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PMID:Studies on lens proteins. III. Variations in polypeptides of lens beta-crystallins. 740 97

Soluble proteins from corter of human fetal clear lenses were separated by column chromatography with Sepharyl S-300 (superfine) and determined by disc-PAGE and SDS-PAGE. The results documented from 18W, 21W (2 cases) and 24W fetal lenses suggested that a negative correlation tended to be presented between the age of fetus and fraction of alpha, beta 1 crystallins (r = -0.9542; r = -0.9674) and a positive correlation between the age of fetus and fraction of beta 2, gamma crystallins (r = 0.9666; r = 0.9970). There was no change in the alpha, beta 1, beta 2 crystallins on disc-PAGE. Among the fetuses of different ages, the blurred band of gamma crystallin seen in 18W and 21W fetal lenses was thickened in the 24W fetal lens. The SDS-PAGE showed that there was no significant difference among the polypeptides in each of alpha, beta 1, beta 2, gamma crystallins in the studied fetal lenses of different age groups. It is presumed that the normal lens is proportionally composed of four fractions of crystallin. This is hypothetically contributed to the maintenance of normal structure of the lens, why the proper proportion of four fractions of crystallins is depended either on proteins synthesis or on protein molecular assembly is not yet clear.
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PMID:[Study on soluble proteins in human fetal lens]. 777 99

This two part study continues and extends our examination of the effects of age and of genetically determined intrinsic growth rate on the overall protein composition of chick lens epithelia, lens fiber masses and whole lenses. Water-soluble proteins were analyzed by SDS-polyacrylamide and 2-dimensional gel electrophoresis. First, detailed age-related changes in protein expression between day 4 of embryonic development and the 8-week adult stage are described for one normal chick strain. Secondly, comparisons are made between day-old post-hatch chicks of four different genotypes: two genetically unrelated chick strains with a high growth rate and propensity for hyperplasia of the lens epithelium and two unrelated slow-growing strains, both with normal lens morphology. We find that the beta/delta-crystallin ratio in lens epithelia and fiber masses is higher in both the slow- than in both the fast-growing strains. The data emphasizes the importance of quantitative and non-coordinate changes in crystallin polypeptide expression during lens growth and development, and implicates growth rate as a modifier of the pattern of crystallin expression.
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PMID:Effects of age and genetic growth rate on the crystallin composition of the chick lens. 777 93

Methylglyoxal is an endogenous metabolite that increases in diabetes and has been implicated in some of its long-term complications such as retinopathy, neuropathy and cataract. We investigated the reaction of methylglyoxal with isolated human and bovine lens crystallins (alpha, beta H, beta L and gamma). After 7 days incubation at 37 degrees C and pH 6.9, the reaction of methylglyoxal with lens proteins yielded stable adducts that exhibited fluorescent properties. SDS-polyacrylamide gel electrophoresis was used to monitor aggregation and crosslinking of the modified protein and autoradiography showed that [14C]methylglyoxal was incorporated into all the protein bands. Bovine gamma-crystallin was the most reactive towards methylglyoxal. Reaction of methylglyoxal with bovine gamma II-crystallin, which is found mainly in the lens nucleus, could alter the change surface network of the molecule, resulting in aggregation, increased light scattering and hence cataract. Modification of gamma II-crystallin by methylglyoxal produced an overall loss of positive charge and an increase in molecular weight and non-disulfide covalent crosslinking. Amino acid analysis of the modified gamma II-crystallin showed a loss of 47% of arginine residues.
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PMID:The reaction of methylglyoxal with human and bovine lens proteins. 782 33

A specific reagent DACM [N-(7-Dimethylamino-4-methyl-3-coumarinyl)maleimide] is used to study the -SH groups in lens proteins of normal and galactose cataractous rats. DACM when reacts readily with -SH groups form strong fluorescent adducts. The two -dimensional electrophoresis with DACM pre-labeled proteins is a simple and sensitive method for detecting -SH groups of protein subunit. In the present study, based on IEF/SDS-PAGE electrophoretically characterized soluble crystallins, describes specific changes in -SH groups of protein subunit during the development of galactose cataract. The contents of -SH groups of crystallins are progressively decreased in cataractous (5+) lens, the reduction of -SH content in alpha- and beta- crystallin protein subunits of the normal and cataractous lens proteins is also noticeable.
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PMID:Assessment of sulfhydryl group in individual rat lens protein subunits during galactose cataract development. 784 79


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