(Investigative Ophthalmology and Visual Science. 2000;41:191-198.)
© 2000
by The Association for Research in Vision and Ophthalmology, Inc.
Effect of UV-A Light on the Chaperone-like Properties of Young and Old Lens 
-Crystallin
Orly Weinreb1,
Martinus Adrianus Maria van Boekel1,
Ahuva Dovrat2 and
Hans Bloemendal1
1 From the Department of Biochemistry, University of Nijmegen, the Netherlands; and the
2 B. Rappaport Faculty of Medicine, Technion–Israel Institute of Technology, Haifa, Israel.
 |
Abstract
|
|---|
PURPOSE. To study the damaging effect of UV-A irradiation on the chaperone-like
properties of 
-crystallin and the subsequent recovery process of
young and old bovine lenses.
METHODS. Young and old bovine lenses were kept in organ culture. After 24 hours
of incubation they were irradiated with UV-A at 365 nm, and optical
quality measurements were performed during the experiments (192 hours).
-Crystallin and A1-, A2-, B1-, and B2-crystallin
subunits were analyzed, separated by gel filtration and cation exchange
chromatography, respectively, after different culture times. Protein
patterns were obtained after two-dimensional (2-D) gel electrophoresis.
Chaperone-like activity was determined on the basis of insulin B-chain
and ßL-crystallin aggregation assays. Aggregation of -crystallin
was analyzed, tryptophan fluorescence measurements were performed, and
-crystallin mRNA levels were determined.
RESULTS. The water-soluble -crystallin obtained from old lenses compared with
young lenses after UV irradiation had decreased chaperone activity, a
higher molecular weight, and increased loss of tryptophan fluorescence.
Moreover, -crystallin mRNA virtually disappeared, whereas extra
spots on the 2-D protein pattern appeared, possibly because of
deamidation.
CONCLUSIONS. -Crystallin obtained from old lenses is more affected by irradiation
than -crystallin derived from young lenses. Moreover, it appeared
that B-crystallin from UV-treated old lenses compared with control
lenses was less susceptible to UV-A than A-crystallin. It may well
be that B-crystallin protects A-crystallin in
vivo.
|
Introduction
|
|---|
The two subunits of the 800-kDa -crystallin aggregate, a major
structural eye lens component, are A-crystallin and
B-crystallin.1
Not long ago, it became apparent that
these subunits are not lens specific, because they also exist in a
variety of other tissues.2
3
Both A- and
B-crystallin belong to the family of small heat shock
proteins.4
Similar to other heat shock proteins A- and
B-crystallin also have chaperone-like activity, which means that
they can assist in refolding of denatured proteins and function in the
prevention of undesired protein association induced by stress
conditions.5
Solar radiation is believed to be one of the major environmental stress
factors involved in cataract formation and may be involved in senile
cataractogenesis too.6
7
8
9
Recent studies10
have shown that during aging and cataract formation, there are some
major posttranslational modifications of A- and B-crystallin that
alter their chaperone properties. Conditions that are assumed to play a
role in these modifications are oxidation, truncation at the C-terminal
region, racemization, phosphorylation of various serines, and
deamidation of Gln and Asn. Studies performed previously show that
exposure of isolated -crystallin to UV-B light at different
wavelengths between 280 and 308 nm is associated with gradual loss of
chaperone–protein efficacy.11
12
13
14
Furthermore, it has
been shown that exposure of bovine lenses to UV-A radiation in
long-term organ culture has a damaging effect on lens enzymes and
proteins.15
16
17
In the present article, we describe the damaging effect of UV-A
irradiation at 365 nm on the individual subunits of -crystallin and
the subsequent recovery process of young and old bovine lenses in
long-term organ culture as monitored by laser scanning of the optical
quality. To extend our knowledge of UV-A–related modifications of
-crystallin acquired from previous studies,16
we
analyzed -crystallin and A- and B-crystallin subunits after
irradiation of the cultured lenses.
The modifications of A- and B-crystallin, paralleled by the
changes of the chaperone-like activity of the subunits after
irradiation were examined and compared with the change of
chaperone-like activity of native -crystallin. Lens mRNA was studied
also to verify whether the observed changes occur at the level of
translation or transcription.
|
Methods
|
|---|
Irradiation of Lens in Organ Culture
Lenses were carefully excised from 1-year-old and 2- to 4-year-old
bovine eyes. For present purposes, lenses a maximum of 1-year-old will
be defined as "young" and those 2 to 4 years old as "old."
After inoculation (2–4 hours) each lens was placed in a specially
designed culture system and irradiated as described
previously.15
16
The lenses received 33
J/cm2 of 365 nm energy when exposed for 75
minutes. The 400-W UV lamp contained a filter that provided radiation
of 8.5 mW/cm2 at 365 nm.16
The
radiation was 7.465 mW/cm2, measured by an IL
1700 Radiometer (International Light, Newburyport, MA). The temperature
of the culture dish did not exceed 37°C. After irradiation, the
optical quality of the lens was monitored throughout the culture
period. Optical measurements were performed as described
earlier.15
18
For each time interval of control and
irradiated lenses we used four young and four old lenses, respectively.
Preparation of Lens Extract and Purification of -Crystallin and
A1-, A2-, B1-, and B2-Crystallin Subunits
Lenses were dissected under a binocular stereomicroscope. A cut
along the equator was made, the epithelium was removed, and the lens
was cut into three parts: cortex, equator, and nucleus. The equator and
the nucleus were immediately stored at -20°C for other assays. Lens
cortex was homogenized in 100 mM Tris buffer at pH 7.5 and spun at
4°C in an Eppendorf (Freemont, CA) tube at 13,000 rpm for 30 minutes.
The supernatant is the water-soluble fraction. The pellet was stored in
5 M urea solution to be examined in forthcoming studies. Separation of
the water-soluble fraction into -, ßH-, ßL-, and 
-crystallin
was performed by gel filtration on Sephacryl S-300 HR (Pharmacia-LKB,
Uppsala, Sweden).19
The column was loaded with 100 mg/ml
water-soluble lens protein, and the separated fractions were measured
automatically at 280 nm. Determination of the aggregation size of
-crystallin fractions from control and UV-irradiated lenses was
performed by comparing elution times on a Superose 6 HR column
(Pharmacia-LKB) in 20 mM sodium phosphate and 100 mM
Na2SO4 (pH 6.9) at a flow rate of 0.5 ml/min.
The relative scattering was monitored at 280 nm. A1-, A2-,
B1-, and B2-crystallin subunits were obtained from -crystallin
by cation exchange chromatography on a CM-52 carboxymethyl cellulose
(Whatman, Clifton, NJ) column (1.5 x 20 cm) at 4°C, using a
gradient buffer ranging from 0.04 M to 0.2 M NaAC in 8 M urea (pH 5.0)
at a flow rate of 0.5 ml/min.20
Protein concentration was
determined using BCA protein assay reagents (Pierce, Rockford, IL).
Mini One- and Two-Dimensional Gel Electrophoresis
Mini one-dimensional gel electrophoresis (13% sodium dodecyl
sulfate) was performed under conditions described by
Laemmli.21
Mini two-dimensional (2-D) polyacrylamide gel
electrophoresis was performed essentially according to the method of
O’Farrell22
for large gels. Minor modifications were made
as described previously.23
Analysis of the resultant
Coomassie blue–stained 2-D gels was performed using a densitometer
(Master-scan; Scanalytics, Billerica, MA) .
Insulin B-Chain and ßL-Crystallin Aggregation Assays
The chaperone-like activity of -crystallin and A1-,
A2-, B1-, and B2-crystallin subunits from control and
UV-irradiated lenses, was determined by two different assays.
Heat-induced aggregation assay of ßL-crystallin was performed at
60°C as described by Horwitz.24
The proteins were
dissolved in 20 mM sodium phosphate, 100 mM
Na2SO4, and 10 mM EDTA (pH
6.9). The scattering was recorded in a spectrophotometer (Lambda
2UV/VIS; Perkin–Elmer, Norwalk, CT) at 360 nm for 30 minutes.
Heat-induced aggregation of the insulin B-chain was performed at 360
nm, 37°C for 20 minutes, as described by Horwitz et al.5
The proteins were dissolved in 20 mM sodium phosphate, 100 mM
Na2SO4, and 10 mM EDTA (pH
6.9). At time 0 of the measurements 0.2 mM dithiothreitol was added.
Both assays were performed in duplicate with a concentration of 250
µg/ml substrate proteins and 100 and 200 µg/ml -crystallin and
A1-, A2-, B1-, and B2-crystallin subunits.
Tryptophan Fluorescence
Tryptophan fluorescence measurements were preformed with 100
µg/ml protein in a 1-ml solution of 20 mM sodium phosphate and 100 mM
Na2SO4 (pH 6.9), with a
fluorescence spectrophotometer (model 650-40; Perkin–Elmer). The
excitation wavelength was set to 295 nm, and the fluorescence emission
was detected at 330 nm.
RNA Isolation and Northern Blotting
Isolation of total RNA from control and irradiated bovine lenses
was performed by reagent assay (Trisol; Gibco, Grand Island, NY).
Twenty micrograms total RNA was denatured with 6 M glyoxal and 50%
dimethyl sulfoxide in 0.1M sodium phosphate buffer (pH 7.0) for 60
minutes at 50°C. The glyoxalated RNA was transferred immediately
after electrophoresis from a 1% agarose gel to pure membrane (Hybond
N+; Amersham, Amersham, UK) by capillary elution using 20x SSC buffer.
Northern blot analyses were hybridized according to Church and
Gilbert,25
by using A- and B-crystallin cDNA
hybridization mixtures. To confirm that equal amounts of RNA were
loaded in each lane, the blots were stripped and hybridized afterward
to an 18S ribosomal probe.
|
Results
|
|---|
Young and old bovine lenses were kept in organ culture.
After 24 hours of incubation they were irradiated with UV-A at 365 nm,
and optical quality measurements were performed during the 8 days (192
hours) of the experiments. The focal length of the position of the
beams passed through young and old lenses during the scans is depicted
in Figure 1
. The focal length represents the focus of the lens. There is no change
of this parameter in control lenses during the culture time. However,
it was shown that 24 hours after irradiation there were some changes of
the focal length of both young and old lenses that returned to control
levels 24 hours later. Ninety-six hours after irradiation, the focal
length changed again, but apparently more in old than in young lenses.
These results led us to restrict the measurements to control and
UV-A–treated young and old lenses that were in the culture 48, 96, and
120 hours, (24, 72, and 96 hours after irradiation), respectively.
View larger version (19K):
[in this window]
[in a new window]
|
Figure 1. Composite of average focal length over time in organ culture for young
and old bovine lenses after UV-A irradiation of 33 J/cm2
compared with control lenses.
|
|
Separation of water-soluble -crystallin from control and
UV-irradiated young and old lenses was performed on a Sephacryl S-300
gel filtration column. The fractions of -crystallin were collected
and analyzed by mini 1- and 2-D polyacrylamide gel electrophoresis (2-D
PAGE). UV-A–induced modifications were observed only in the 2-D PAGE
pattern, as shown in Figures 2
and 3
. The damaging effect of UV-A irradiation on water-soluble
A-crystallin is reflected by extra spots (arrows in Fig. 2b
), which
were seen and scanned 24 hours after irradiation. These spots had the
same molecular weight as A-crystallin in young lenses. In addition,
in old lenses there were spots with the same molecular weight as A-
and B-crystallin (arrows in Figs. 3b
and 3c
). In view of the
localization and migration distance of the extra spots, they may be due
to deamidation of A- and B-crystallin components, as is the case
in chicken lenses.26
Although these extra spots still
existed in old lenses 72 hours after irradiation (Fig. 3c) , in young
lenses they were not observed at this time point (compare Fig. 2c
).
View larger version (80K):
[in this window]
[in a new window]
|
Figure 2. Mini 2-D PAGE of water-soluble -crystallin fraction obtained from
the cortex of cultured young bovine lenses. (a) Protein
profile of control lens after 120 hours’ culturing, (b)
after 48 hours’ culturing (24 hours after irradiation), (c)
after 96 hours’ culturing (72 hours after irradiation), and
(d) after 120 hours’ culturing (96 hours after
irradiation). Arrows: extra spots. IEF, isoelectric
focusing.
|
|
View larger version (92K):
[in this window]
[in a new window]
|
Figure 3. Mini 2-D PAGE of water-soluble -crystallin fraction obtained from
the cortex of cultured old bovine lenses. (a) Protein
profile of control lens after 120 hours’ culturing, (b)
after 48 hours’ culturing (24 hours after irradiation), (c)
after 96 hours’ culturing (72 hours after irradiation), and
(d) after 120 hours’ culturing (96 hours after
irradiation). Arrows: extra spots. IEF, isoelectric
focusing.
|
|
The chaperone properties of the purified water-soluble -crystallin
fractions were determined by insulin B-chain and ßL-crystallin
aggregation assays with different concentrations of -crystallin. Our
results show that -crystallin from old bovine lenses possesses only
a decreased chaperone-like activity, in agreement with other studies
described previously.27
There is no significant difference
between -crystallin activity detectable from control and
UV-irradiated young lenses (not shown). Figure 4
illustrates the chaperone-like activity of different concentrations of
the water-soluble -crystallin from old control and UV-irradiated
lenses, which was performed with the insulin assay (Figs. 4a
and 4c)
and the heating assay with ßL-crystallin (Figs. 4b
and 4d)
. The
results are summarized in Figure 4e
. A decrease of 20% of chaperone
activity occurred (with 100 and 200 µg -crystallin) 72 hours after
irradiation. Twenty-four hours later, the chaperone ability recovered,
measured by insulin assay. In the heating assay, the chaperone activity
of -crystallin decreased by 30% with 200 µg -crystallin and by
55% with 100 µg protein at 72 hours after irradiation and slightly
recovered 24 hours later by 10% and 20%, respectively.
Tryptophan fluorescence measurements were performed with -crystallin
fractions from control and irradiated young and old lenses to verify
whether conformational changes might have occurred (Fig. 5)
. -Crystallin from young lenses showed decreased values of
tryptophan fluorescence 24 hours after irradiation and returned to the
control level 96 hours after irradiation. -Crystallin from old
lenses showed up to a 2.5-fold loss of tryptophan fluorescence as a
function of time after irradiation and only a slight recovery 96 hours
after irradiation. In view of the these results, further experiments
were restricted to old lenses.
View larger version (23K):
[in this window]
[in a new window]
|
Figure 5. The relative tryptophan fluorescence (excitation at 295 nm/emission at
330 nm) of water-soluble -crystallin fraction obtained from control
and UV-A–irridiated young and old bovine lenses. Error bars, SD of
four different measurements each.
|
|
Determination of the aggregation size of -crystallin from control
and UV-irradiated old lenses was performed by comparing elution times
on a Superose 6 HR column (Fig. 6)
. -Crystallin aggregates from UV-treated lenses (72 and 96 hours
after irradiation) seemed to be larger than in the control samples.
View larger version (17K):
[in this window]
[in a new window]
|
Figure 6. Elution profile of comparative gel permeation chromatography on a
Superose 6 HR column to determine the aggregation size of
water-soluble -crystallin fractions from control and
UV-A–irridiated old bovine lenses. The relative scattering was
monitored at 280 nm.
|
|
A1-, A2-, B1-, and B2-crystallin subunits were obtained
from the water-soluble -crystallin of old 96-hour cultured lenses
(72 hours after irradiation) after cation exchange chromatography on a
CM-52 carboxymethyl cellulose column (data not shown). The purity of
the yielded fractions was approximately 95% as shown
previously.20
The chaperone properties of the purified subunits of -crystallin
were determined by insulin B-chain and ßL-crystallin aggregation
assays, as shown in Figure 7
. Both phosphorylated A- and B-crystallin subunits (A1, B1)
seem to be better chaperones than nonphosphorylated subunits (A2,
B2) derived from control and irradiated lenses. Measurements with
the heating assay (Figs. 7b
and 7d)
indicate that A-crystallin from
control lenses provided better protection than B-crystallin, in
agreement with a previous study.28
With the insulin assay,
however, both A- and B-crystallin from control lenses provided
protection (Figs. 7a
and 7c)
. Comparison of B-crystallin to
A-crystallin chaperone activity in control lenses with that of
irradiated lenses, as measured by the insulin assay and the heating
assay, shows that B-crystallin from UV-treated lenses was a better
chaperone than A-crystallin. A-crystallin from irradiated lenses
lost almost all its chaperone activity, measured with the heating
assay.
To check whether UV damage occurs at the level of transcription or mRNA
degradation, total RNA was isolated from control and irradiated old
bovine lenses, followed by hybridization with A- and B-crystallin
cDNA probes. Using an rRNA probe as a control (Fig. 8
a), it appeared that A- and B-crystallin mRNA degraded at 72 hours
after irradiation, whereas 24 hours later synthesis started again
(Figs. 8b
and 8c)
.
|
Discussion
|
|---|
We investigated in situ the effect of UV-A irradiation on
the chaperone-like ability of -crystallin and its subunits from
young and old cultured bovine lenses to create similar conditions and
effects in the lens as those that take place during solar radiation.
In a comparison of untreated with UV-A–treated lenses, it appeared
that the water-soluble fractions of -crystallin obtained from old
lenses were more affected than -crystallin derived from young
lenses. For instance, such effects were: decreased ability of
-crystallin to inhibit protein denaturation in vitro, higher
molecular weight of the -crystallin fractions, loss of tryptophan
fluorescence, degradation of -crystallin mRNA, and the appearance of
extra spots on the 2-D pattern, possibly because of deamidation. These
phenomena were paralleled by a higher damage of the optical quality of
old lenses compared with young lenses. But at the time that lenses
started to recover, measured by the focal length repair, the
chaperone-like activity recovered, tryptophan fluorescence increased,
and the extra spots with the same subunit molecular weight of A- and
B-crystallin disappeared. Previous work15
has shown
that some metabolic enzymes also can recover from UV-A damage. The
increase in A- and B-crystallin mRNA levels may play a role in
the recovery, because de novo synthesis of -crystallin can occur in
the outer cortex of the lenses.
Studies of the effect of UV-B on A-crystallin29
have shown specific racemization and isomerization after irradiation.
Our results show that A-crystallin from old lenses seemed to be more
susceptible to UV-A than B-crystallin, which provided a better
protection to denatured proteins. The differences in results obtained
with the insulin and the heating assay may be due to A-crystallin’s
inability to function properly as a chaperone. It appeared from this
study and from other work28
that B-crystallin was
temperature sensitive and therefore had less chaperone capacity at
elevated temperatures than A-crystallin. In contrast,
B-crystallin from UV-treated lenses compared with control lenses was
a better chaperone than A-crystallin, which lost almost all its
chaperone-like activity after irradiation. It may well be that
B-crystallin and A-crystallin protect each other as the subunits
interact in vivo. Moreover, our results are consistent with previous
work,28
because phosphorylated A- and B-crystallin
subunits (A1, B1) are better chaperones than the
nonphosphorylated subunits (A2, B2) from control and UV-A
irradiated lenses.
Identification of the photo-oxidation sites (UV-B) in bovine
-crystallin30
indicates that the N-terminal regions of
A- and B-crystallin are exposed to an aqueous environment and are
in the vicinity of tryptophan residues from neighboring subunits. Our
study shows a decrease of tryptophan fluorescence of isolated bovine
-crystallin from lenses exposed to UV-A light. Posttranslation
modifications and formation of high molecular aggregates of A-and
B-crystallin after UV-A irradiation can lead to changes of the
chaperone-like properties that may affect the integrity of other key
proteins involved in the structure of the cytoskeleton. In turn, this
may result in opacification of the lens during aging.
|
Acknowledgements
|
|---|
The authors thank Wilfried de Jong for valuable advice and Anke van
Rijk, Perry Overkamp, and Neil Azzam for technical assistance.
|
Footnotes
|
|---|
Supported by a Marie Curie Research Training Grant in Biotechnology from the European Commission for Science, Research, and Development
(Bio. 4-CT96-5121) and in part by the Matrix Biology Institute, Ridgefield, New Jersey.
Submitted for publication January 7, 1999; revised April 23 and June 28, 1999; accepted July 28, 1999.
Commercial relationships policy: N.
Corresponding author: Hans Bloemendal, Department of Biochemistry, University of Nijmegen, P. O. Box 101, 6500 HB Nijmegen, the
Netherlands. h.bloemendal{at}bioch.kun.nl
|
References
|
|---|
-
Bloemendal, H. (1977) The vertebrate eye lens Science 197,127-138[Free Full Text]
-
Bhat, SD, Nagineni, CN (1989) AlphaB subunit of lens-specific protein alpha crystallin is present in other ocular and non-ocular tissues Biochem Biophys Res. Commun. 158,319-325[Medline][Order article via Infotrieve]
-
Groenen, PJA, Merck, KB, de Jong, WW, Bloemendal, H. (1994) Structure and modification of the junior chaperone -crystallin from lens transparency to molecular pathology Eur J Biochem 225,1-19[Medline][Order article via Infotrieve]
-
de Jong, WW, Leunissen, JAM, Voorter, CEM (1993) Evolution of the -crystallin/small heat-shock protein family Mol Biol Evol 10,103-126[Abstract]
-
Horwitz, J, Huang, QL, Ding, L, Bova, MP (1998) Lens -crystallin: chaperone-like properties Methods Enzymol 290,365-383[Medline][Order article via Infotrieve]
-
Taylor, HR (1989) Ultraviolet radiation and the eye lens: an epidemiologic study Trans Am Ophthalmol Soc 87,802-853[Medline][Order article via Infotrieve]
-
Stevens, MA, Bergmanson, JPG (1989) Dose sunlight cause premature aging of the crystalline lens? J Am Opt Assoc 60,660-663
-
Young, RW (1992) Sunlight and age-related eye diseases J Natl Med Assoc 84,353-358[Medline][Order article via Infotrieve]
-
West, SK (1993) Daylight, diet, and age-related cataract Optom Vis Sci 70,869-872[Medline][Order article via Infotrieve]
-
Takemoto, LJ, Boyle, D. (1998) The possible role of -crystallin in human senile cataractogenesis Int J Biol Macromol 22,331-337[Medline][Order article via Infotrieve]
-
Schauerte, JA, Gafni, A. (1995) Photodegradation of tryptophan residues and attenuation of molecular chaperone activity in -crystallin are correlated Biochem Biophys Res Commun 212,900-905[Medline][Order article via Infotrieve]
-
Borkman, RF, McLaughlin, J. (1995) The molecular chaperone function of -crystallin is impaired by UV photolysis Photochem Photobiol 62,1046-1051[Medline][Order article via Infotrieve]
-
Ellozy, AR, Ceger, P, Wang, RH, Dillon, J. (1996) Effect of the UV modification of -crystallin on its ability to suppress nonspecific aggregation Photochem Photobiol 64,344-348[Medline][Order article via Infotrieve]
-
Lee, JS, Liao, JH, Wu, SH, Chiou, SH (1997) -Crystallin acting as a molecular chaperone against photodamage by UV irradiation J Protein Chem 16,283-289[Medline][Order article via Infotrieve]
-
Dovrat, A, Weinreb, O. (1995) Recovery of lens optics and epithelial enzymes after ultraviolet A radiation Invest Ophthalmol Vis Sci 36,2417-2424[Abstract/Free Full Text]
-
Weinreb, O, Dovrat, A. (1996) Transglutaminase involvement in UV-A damage to the eye lens Exp Eye Res 63,591-597[Medline][Order article via Infotrieve]
-
Weinreb, O, Dovrat, A. (1999) Effect of UV-A radiation on lens epithelial Na,K-ATPase in organ culture Invest Ophthalmol Vis Sci 40,1616-1620[Abstract/Free Full Text]
-
Sivak, JG, Yoshimura, M, Weerheim, J, Dovrat, A. (1990) Effect of hydrogen peroxide, DL-propranolol and prednisone on the bovine lens optical function in culture Invest Ophthalmol Vis Sci 31,954-963[Abstract/Free Full Text]
-
Slingsby, C, Bateman, O A. (1991) Rapid separation of bovine ß-crystallin subunits ßB1, ßB2, ßB3, ßA3 and ßA4 Exp Eye Res 51,21-26
-
de Jong, WW, van Kleef, FSM, Bloemendal, H. (1974) Intracellular carboxyl-terminal degradation of the A chain of -crystallin Eur J Biochem 48,271-276[Medline][Order article via Infotrieve]
-
Laemmli, UK (1970) Cleavage of structural proteins during the assembly of the head of bacteriophage T4 Nature 227,680-685[Medline][Order article via Infotrieve]
-
O'Farrell, PH. (1975) High resolution two-dimensional electrophoresis of protein J Biol Chem 250,4007-4021[Abstract/Free Full Text]
-
Bloemendal, H, Van de gaer, K, Benedetti, EL, Dunia, I, Steely, HT. (1996) Towards a human crystallin map: two-dimensional gel electrophoresis and computer analysis of water-soluble crystallin from normal and cataractous human lenses Ophthalmic Res 29,177-190
-
Horwitz, J. (1992) -Crystallin can function as a molecular chaperone Proc Natl Acad Sci USA 89,10449-10453[Abstract/Free Full Text]
-
Church, WH, Gilbert, W. (1984) Genomic sequencing Proc Natl Acad Sci USA 81,1991-1995[Abstract/Free Full Text]
-
Voor, CEM, Roersma, ES, Bloemendal, H, de Jong, WW (1987) Age-dependent deamidation of chicken A-crystallin FEBS Lett 221,249-252[Medline][Order article via Infotrieve]
-
Horwitz, J, Emmons, T, Takemoto, L. (1992) The ability of lens alpha crystallin to protect heat-induced aggregation is age-dependent Curr Eye Res 11,817-822[Medline][Order article via Infotrieve]
-
van Boekel, MAM, Hoogakker, SEA, de Jong, WW (1996) The influence of some post-translational modifications on the chaperone-like activity of -crystallin Ophthalmic Res 28,32-38
-
Fuji, N, Momose, Y, Ishibashi, Y, Uemura, T, Takita, M, Takehana, M. (1997) Specific racemization and isomerization of the aspartyl residue of A-crystallin due to UV-B irradiation Exp Eye Res 65,99-104[Medline][Order article via Infotrieve]
-
Finley, EL, Busman, M, Dillon, J, Crouch, RK, Schey, KL (1997) Identification of photooxidation sites in bovine -crystallin Photochem Photobiol 66,635-641[Medline][Order article via Infotrieve]
This article has been cited by other articles:
|
|
|
|
 
G. Thiagarajan, J. Lakshmanan, M. Chalasani, and D. Balasubramanian
Peroxynitrite Reaction with Eye Lens Proteins: {alpha}-Crystallin Retains Its Activity Despite Modification
Invest. Ophthalmol. Vis. Sci.,
July 1, 2004;
45(7):
2115 - 2121.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
