Goat Lens Research Articles

Phytochemical characterization and evaluation of anticataract potential of seabuckthorn leaf extract.

This study was undertaken to carry out phytochemical characterization of aqueous extract of Seabuckthorn (SBT, Hippophae rhamnoides L.) leaves and evaluation of its therapeutic role in oxidative stress-induced cataract in isolated goat lenses using Vit. E as reference compound. A total of 42 goat eye lenses were used in the present study. Seabuckthorn leaf extract was characterized by total phenol content estimation and HPLC analysis of quercetin and catechin. Further, cataract was induced in goat lenses using hydrogen peroxide (H2O2) and anticataract activity was evaluated using the extract in the dose range of 100, 200, 500, and 1000 μg/mL concentrations through estimation of biochemical markers such as superoxide dismutase (SOD), reduced glutathione (GSH), and malonaldehyde (MDA). The results of the phytochemical characterization showed the total phenol content of the extract to be 365 mg/g in terms of gallic acid equivalents. Quercetin and catechin were estimated to be 0.01 and 0.12% w/w, respectively. In biochemical analysis, H2O2 introduction resulted in a decrease in SOD (approximately 85%) and GSH (approximately 63%) contents and an increase in MDA content (approximately 300%). The decreased levels of SOD and GSH were significantly restored in experimental groups receiving 500 and 1000 1g/mL of SBT extract. All the experimental groups showed significantly reduced MDA level in all the doses. Aqueous extract of SBT leaves showed the potential to delay onset and/or progression of cataract, at least during in vitro conditions. Results indicate the possibilities of evaluating this extract for its use as anticataract agent during in vivo conditions.

Bioactive fraction of Saraca indica prevents diabetes induced cataractogenesis: An aldose reductase inhibitory activity.

Background:The present study was designed to investigate the effect of Saraca indica (SI) flowers extract and different bioactive fraction on in vitro aldose reductase (AR) inhibitory activity, high glucose-induced cataract in goat lens and in vivo streptozotocin (STZ; 45 mg/kg, i.p) induced cataract in rats.Methods:Extract of flowers of SI tested for inhibition against rat lens AR. Furthermore, bioactive fraction was investigated against high glucose-induced opacification of the lens in vitro lens culture and STZ induced diabetic cataract in rats. Identification of the bioactive component was attempted through high-performance thin-layer chromatography, high-performance liquid chromatography and liquid chromatography-mass spectrometry analysis.Results:Ethyl acetate fraction of S. indica (EASI) produced maximum inhibition that may be due to high phenolic content. Goat lenses in media containing glucose developed a distinctly opaque ring in 72 h and treatment with EASI fraction lowered lens opacity in 72 h. Prolonged treatment with EASI to STZ-induced diabetic rats inhibited the AR activity and delayed cataract progression in a dose dependent manner.Conclusion:Ethyl acetate fraction of S. indica fraction has potential to inhibit rat lens AR enzyme and prevent cataractogenesis not only in goat lens model (in vitro), but also in STZ induced diabetic rats (in vivo). This study is suggestive of the anticataract activity of EASI fraction that could be attributed to the phytoconstituents present in the same.

Investigation of Carvedilol as an Antidenaturing and Anticataract Agent

Cataract is an opacification of the lens of eye. Causes of cataract formation are aging, generation of free radicals, diabetes, protein denaturation by oxidative stress or any inducer etc. Antioxidants and antioxidant enzymes, antidenaturing agent protect the eyes by reducing free radical damage and eye lenses by inhibiting protein denaturation. The present study evaluated the in vitro anticataract and antidenaturing activities of carvedilol against glucose-induced cataractogenesis using goat lenses and heat induced egg albumin denaturation. Transparent isolated goat lenses are incubated in artificial aqueous humor and divided into five experimental groups. The carvedilol at a dose of 20μg/ml is incubated simultaneously with glucose (55 mM) and glucose (5.5 mM) for a period of 72 h. ascorbic acid (20 μg/ml) is used as the standard drug. At the end of the incubation lense opacity is measured by photographic evaluation. Antidenaturing activity is evaluated by taking different concentration of carvedilol (10 p.p.m – 500 p.p.m) with egg albumin and subjected for protein denaturation by using heat for 15 min. Standard drug is used as Diclofenac sodium, at the end protein denaturation is analyse by taking absorbance at 440 nm and 660 nmrsp. The carvedilol shows significant inhibition of cataractogenesis of eye lenses by carvedilol at conc. 20 p.p.m. and also thermally induced protein denaturation inhibited by carvedilol at conc. 500 p.p.m. The present supports carvedilol as an antidenaturing and anticataract agent.

Evaluation of Echitamine, Ditamine and Echitenine for Anticataract Activity using in vitro cataract Model

The alkaloids such as echitamine, ditamine and echitenine were subjected for anti cataract activity using in vitro cataract model. Goat lenses were incubated in artificial aqueous humor containing 55 mM glucose with test alkaloids in different concentrations at room temperature for 72 h. Studied Biochemical parameters were sodium ion, potassium ion level and Na+-K+-ATPase activity. Glucose induced opacification of goat lens began 8-10 hrs after incubation and was complete in 72-80 hrs. Cataractous lenses treated with echitamine shown lower sodium ion, higher the potassium ion and higher Na+-K+-ATPase activity. Echitamine treated lens prevented formation and progress of cataract as evidenced by biochemical parameters and visual observation. Ditamine and echitenine were devoid of anti - cataract activity.

Studies on the anticataract activity of echitamine, an alkaloid from the stem bark of Alstonia scholaris.

The phytoconstituent echitamine isolated from stem bark of Alstonia scholaris was subjected for in vitro cataract prevention study on glucose induced cataract model. Goat lenses were incubated with test drugs in different concentrations at room temperature for 72 h. Biochemical parameters studied in the lens were electrolytes Na+, K+ and Na+-K+-ATPase activity. Cataractous lens treated with drug shown lower Na+, higher K+ and higher Na+-K+-ATPase activity. Lens treated with echitamine prevented formation and progress of cataract induced by glucose. Keywords; Cataract, Echitamine, Alstonia Scholaris

Effect of standardized fruit extract of Luffa cylindrica on oxidative stress markers in hydrogen peroxide induced cataract.

Objective:The ability of Luffa cylindrica Roem fruit extract (LCE) to modulate biochemical parameters was investigated by in vitro studies for its role in hydrogen peroxide induced cataract on isolated goat lenses which were incubated for 72 h at 37°C.Materials and Methods:Test groups contained 5, 10, 15, 20, 25, and 30 µg/ml of LCE along with 1 ml of H2O2 (0.5 mM) as cataract inducer. Lenses were examined for morphological variation and transparency periodically during the incubation. Biochemical parameters such as superoxide dismutase (SOD), reduced glutathione (GSH), total protein content (TPC), and malondialdehyde (MDA) were estimated.Results:SOD, GSH, and TPC levels were found to increase proportionally with the concentration of LCE. However, MDA levels were found to be inversely proportional to the concentration of LCE. Opacity was graded as per “lens opacities classification system III.” Morphological examination suggested that LCE (25 µg/ml) maintained a vision for 44 h. No lens in LCE dose groups developed dense nuclear opacity after 24 h as opposed to 80% in negative control.Conclusion:The results suggest that LCE can delay the onset and/or prevent the progression of cataract which can be attributed to the presence of adequate phenolics, flavonoids, and Vitamin A and its high nutritional value. This preliminary study can be further synergized by testing LCE against other in vivo and in vitro models of cataract.

In vitro anti-cataract evaluation of standardised Abies pindrow leaf extract using isolated goat lenses

Oxidative stress is known to spark off the pathogenesis of cataract. Antioxidant potential of Abies pindrow Royle leaf extract (APE) is well established in the literature. In this context, standard aqueous leaf extract of this plant was evaluated for its role in hydrogen peroxide-induced cataract in isolated goat lenses using varying concentrations (5, 10, 15 and 20 mg/mL). Total phenol and flavonoidal content was evaluated and found to be high in concentration. Biochemical parameters, namely superoxide dismutase (SOD), glutathione (GSH), total protein content (TPC) and malondialdehyde (MDA), were evaluated. SOD, GSH and TPC formation was found to increase proportionally with increasing concentration. However, MDA level decreased significantly as the concentration of the extract increased. The results suggest that the extract under investigation can delay the onset and/or prevent the progression of cataract. Its anti-cataract potential may be attributed to the presence of high phenolics and flavonoids in APE. Photographic evaluation, further, confirmed the observation.

Development of novel pyrazolone derivatives as inhibitors of aldose reductase: An eco-friendly one-pot synthesis, experimental screening and in silico analysis

Aldose reductase is the key enzyme of polypol pathway leading to accumulation of sorbitol. Sorbitol does not diffuse across the cell membranes easily and therefore accumulates within the cell, causing osmotic damage which leads to retinopathy (cataractogenesis), neuropathy and other diabetic complications. Currently, aldose reductase inhibitors like epalrestat, ranirestat and fidarestat are used for the amelioration of diabetic complications. However, such drugs are effective in patients having good glycemic control and less severe diabetic complications. In present study we have designed novel pyrazolone derivative and performed eco-friendly synthesis approach and tested the synthesized compounds as potential inhibitors of aldose reductase activity. Additional in silico analysis in current study indicates presence of highly conserved chemical environment in active site of goat lens aldose reductase. The reported data is expected to be useful for developing novel pyrazolone derivatives as lead compounds in the management of diabetic complications.

Vegetables' juice influences polyol pathway by multiple mechanisms in favour of reducing development of oxidative stress and resultant diabetic complications.

Objective:Hyperglycemia induced generation of free radicals and consequent development of oxidative stress by polyol pathway is one of the crucial mechanisms stirring up development of diabetic complications. We evaluated influence of ten vegetables’ juice on polyol pathway along with their antioxidant and antioxidative stress potentials.Materials and Methods:Aldose reductase activity was determined utilising goat lens and human erythrocytes. In goat lens, utilization of nicotinamine adenine dinucleotide phosphate (NADPH) and aldose reductase inhibition was assayed. In human erythrocytes, sorbitol formation was measured as an index of aldose reductase activity under normoglycemic and hyperglycemic conditions. Ability of juices in inhibiting oxidative damage to deoxyribose sugar and calf thymus DNA and inhibitory activity against hydrogen peroxide induced hemolysis of erythrocytes was also analysed. Phytochemical contents like total polyphenol, total flavonoid and total protein were measured to find their influence on biological activities.Results:Vegetables’ juice displayed varying degrees of inhibitory potentials in mitigating NADPH dependent catalytic activity of aldose reductase in goat lens, accumulation of sorbitol in human erythrocytes under different glucose concentrations; Fenton-reaction induced oxidative damage to deoxyribose sugar, and calf thymus DNA. Substantial variations in vegetables phytochemicals content were also noticed in this study.Conclusions:Vegetables’ juice possesses potent activities in influencing polyol pathway by various mechanisms in favour of reducing development of oxidative stress independent of their inherent antioxidative properties. Juice of ivy gourd followed by green cucumber and ridge gourd were among the most potent for they displayed strong activities on various parameters analysed in this study. These vegetables’ juice may become part of mechanism-based complementary antioxidant therapy to prevent development of diabetic complications.

Evaluation of in vitro aldose reductase inhibitory potential of alkaloidal fractions of Piper nigrum, Murraya koenigii, Argemone mexicana, and Nelumbo nucifera

Aldose reductase is primarily involved in development of long-term diabetic complications due to increased polyol pathway activity. The synthetic aldose reductase inhibitors are not very successful clinically. Therefore, the natural sources may be exploited for safer and effective aldose reductase inhibitors. In the present study, the aldose reductase inhibitory potential of hydroalcoholic and alkaloidal extracts of Piper nigrum, Murraya koenigii, Argemone mexicana, and Nelumbo nucifera was evaluated. The hydroalcoholic and alkaloidal extracts of the selected plants were prepared. The different concentrations of hydroalcoholic and alkaloidal extracts of these plants were evaluated for their goat lens aldose reductase inhibitory activity using dl-glyceraldehyde as substrate. The aldose reductase inhibitory potential of extracts was assessed in terms of their IC50 value. Amongst the hydroalcoholic extracts, the highest aldose reductase inhibitory activity was shown by P. nigrum (IC50 value 35.64±2.7 μg/mL) followed by M. koenigii (IC50 value 45.67±2.57 μg/mL), A. mexicana (IC50 value 56.66±1.30 μg/mL), and N. nucifera (IC50 value 59.78±1.32 μg/mL). Among the alkaloidal extracts, highest inhibitory activity was shown by A. mexicana (IC50 value 25.67±1.25 μg/mL), followed by N. nucifera (IC50 value 28.82±1.85 μg/mL), P. nigrum (IC50 value 30.21±1.63 μg/mL), and M. koenigii (IC50 value 35.66±1.64 μg/mL). It may be concluded that the alkaloidal extracts of these plants possess potent aldose reductase inhibitory activity and may be therapeutically exploited in diabetes-related complications associated with increased activity of aldose reductase.

Antioxidant potential of Emblica officinalis (amla) aqueous extract delays cataractogenesis in hyperglycemic goat lenses

Aim: To study the antioxidant role of Emblica officinalis aqueous extract in delaying cataractogenesis in hyperglycemic goat lenses. Study design: Experimental study. Place and Duration of study: Department of Biochemistry, Bharati Vidyapeeth Deemed University Medical College, Pune, India, between February 2012 to June 2012. Methodology: Dried powder of Emblica officinalis fruit pericarp was obtained and crude water extract was prepared. Fresh goat lenses were removed from the eyeballs and divided into 3 groups as follows: Group I Normal lenses ,incubated in Tissue Culture medium 199 (TC199), Group II & IIIExperimental Cataract lenses incubated with TC 199 + 110mM Dextrose solution and TC 199 + 110mM Dextrose solution + 0.25% E.officinalis aqueous extract respectively. After 72 hours of incubation, lenses were homogenized in 0.1M sodium phosphate buffer, pH 7.4 and the supernatant was used for biochemical analysis. Effect of the extract on lens total soluble proteins, TBARS and antioxidant enzymes superoxide dismutase, glutathione peroxidase and glutathione reductase was statistically analyzed. Results: The lens total soluble proteins were maintained, TBARS were reduced and there was a significant rise in the activity of antioxidant enzymes SOD, glutathione peroxidase and glutathione reductase in the lenses incubated with the E.officinalis extract as compared to hyperglycemic lenses. Conclusion: The study highlights the antioxidant nature of E.officinalis which may play an important role in the prevention of hyperglycemia induced cataract.

In vitro prevention of cataract by Oyster Mushroom Pleurotus florida extract on isolated goat eye lens

Objectives:The aim of the present work was to evaluate the in vitro effect of Pleurotus florida extract cataract induced by glucose.Materials and Methods:Goat eye lenses were divided into four groups. Group I lenses were incubated in artificial aqueous humor with glucose concentration 5.5 mM (normal control). Group II lenses were incubated with glucose concentration 55 mM (toxic control). Group III and IV lenses incubated with glucose concentration 55 mM were incubated along with hydroethanolic extract of P. florida 250 μg/ml and 500 μg/ml and subjected to morphological and biochemical evaluation.Results:Group II lenses showed high amount of malondialdehyde (MDA) soluble and insoluble protein and decreased catalase and glutathione levels, while lenses treated with P. florida extract showed significant (P < 0.05) reduction in MDA, increased level of catalase (P < 0.001), glutathione (P < 0.005) and total and soluble protein.Conclusions:Hydroethanolic extract of P. florida showed prevention of in vitro glucose induced cataract. Thus, the goat lens model could be used for testing of various anticataract agents.

Delay of diabetic cataract in rats by the antiglycating potential of cumin through modulation of α-crystallin chaperone activity

α-Crystallin, a molecular chaperone of the eye lens, plays an important role in maintaining the transparency of the lens by preventing the aggregation/inactivation of several proteins and enzymes in addition to its structural role. α-Crystallin is a long-lived protein and is susceptible to several posttranslational modifications during aging, more so in certain clinical conditions such as diabetes. Nonenzymatic glycation of lens proteins and decline in the chaperone-like function of α-crystallin have been reported in diabetic conditions. Therefore, inhibitors of nonenzymatic protein glycation appear to be a potential target to preserve the chaperone activity of α-crystallin and to combat cataract under hyperglycemic conditions. In this study, we investigated the antiglycating potential of cumin in vitro and its ability to modulate the chaperone-like activity of α-crystallin vis-à-vis the progression of diabetic cataract in vivo. Aqueous extract of cumin was tested for its antiglycating ability against fructose-induced glycation of goat lens total soluble protein (TSP), α-crystallin from goat lens and a nonlenticular protein bovine serum albumin (BSA). The antiglycating potential of cumin was also investigated by feeding streptozotocin (STZ)-induced diabetic rats with diet containing 0.5% cumin powder. The aqueous extract of cumin prevented in vitro glycation of TSP, α-crystallin and BSA. Slit lamp examination revealed that supplementation of cumin delayed progression and maturation of STZ-induced cataract in rats. Cumin was effective in preventing glycation of TSP and α-crystallin in diabetic lens. Interestingly, feeding of cumin to diabetic rats not only prevented loss of chaperone activity but also attenuated the structural changes of α-crystallin in lens. These results indicated that cumin has antiglycating properties that may be attributed to the modulation of chaperone activity of α-crystallin, thus delaying cataract in STZ-induced diabetic rats.

Transcorneal permeation of ciprofloxacin and diclofenac from marketed eye drops

The purpose of this research was to evaluate the in vitro permeation characteristics of various marketed eye drops of ciprofloxacin (0.3% w/v aqueous solution) and diclofenac (0.1% w/v aqueous solution) through isolated goat cornea. Effect of these drugs on isolated goat eye lenses was also evaluated. Permeation studies were conducted by putting 1 ml of formulation on the cornea fixed between the donor and receptor compartments of an all glass modified Franz diffusion cell and monitoring ciprofloxacin and diclofenac concentration in the receptor (containing normal saline or bicarbonate ringer solution under continuous stirring at 37±2°) spectrophotometrically at their respective absorption maxima, after 120 min. Paired isolated goat lenses (i.e. of same animal) were used to evaluate the effect of these drugs at selected concentrations against oxidative stress (1 mM hydrogen peroxide solution). After 24 h of incubation at 37°, the lens treated with test solution (hydrogen peroxide+drug in bicarbonate ringer solution) was estimated for soluble protein content and compared with control (only hydrogen peroxide). Among marketed eye drops of ciprofloxacin, Joxin (Jawa Pharmaceuticals) showed maximum in vitro transcorneal permeation (0.558%) while I-Gesic (Centaur Pharmaceuticals) showed maximum % in vitro permeation or in vitro ocular availability among diclofenac eye drops after 120 min of permeation. The soluble protein content estimation studies revealed that these drugs at selected concentrations (permeated after 120 min.) had no deleterious effect on eye lenses rather possessed protective effect, since all formulation showed more soluble protein content when compared with control.

In vitroprevention by ACE inhibitors of cataract induced by glucose

Objectives: To study, the anticataract activity of lisinopril and enalapril on cataract induced by glucose, in goat lenses. Materials and Methods: Goat lenses were incubated in artificial aqueous humor containing 55 mM glucose (cataractogenesis) with lisinopril or enalapril in different concentrations at room temperature for 72 h. Biochemical parameters studied in the lens were electrolytes (Na+, K+), Na+-K+-ATPase activity, malondialdehyde (MDA) and proteins. Results: Glucose induced opacification of goat lens began 8-10 hrs after incubation and was complete in 72-80 hrs. Cataractous lenses showed higher Na+, MDA (P Conclusion: The anticataract activity of lisinopril and enalapril may be because of the antioxidant and free radical scavenging activity, as evidenced by a decrease in MDA in treated lenses. Further in-vitro and in-vivo studies in various experimental models and long term clinical trials are required to validate the anticataract activity of ACE-inhibitors.

Impedance of Goat Lens as a Function of Frequency at DC Voltages 0, 50, 100, 200 mV

Impedance characteristics of lens tissue has been studied using the AC impedance system (EG&G PARC, model 318) at different low voltage excitations using a Cole-Cole Plot. The extracellular resistance (Re), intracellular resistance (Ri), depressed angle (θ), total impedance (IZI), and phase angle (ϕ) of the tissue were measured. The impedance locus between the real part (Z′) and imaginary part (Z″) of the complex impedance of lens was examined at discrete frequencies ranging from 10 mHz to 10 Hz. A decrease in extra-cellular resistance (Re) and increase in distribution of the factor (α) of 56.8 KΩ, 48.1 KΩ, 32.8 KΩ, 13.4 KΩ, and 0.40, 0.43, 0.46, 0.53 were found at 0 mV, 50 mV, 100 mV, and 200 mV, respectively. The total impedance (| Z|) and phase angle (ϕ) were also evaluated and the observed frequency dependent for the frequency range was tested as a function of excitation voltage. An attempt has been made to explain the effect of voltage stress on lens impedance.

Effect of Diabecon on sugar-induced lens opacity in organ culture: mechanism of action

Cataract is the leading cause of blindness worldwide. Apart from ageing, diabetes has been considered to be one of the major risk factors of cataract. The high sugar levels in diabetes may cause tissue disruption and intumescences by osmotic changes induced via aldose reductase (AR) mediated polyol pathway. Therefore, agents that can inhibit AR and prevent sorbitol accumulation may be helpful to combat sugar-induced cataract. In the present study, AR inhibitory activity of Diabecon (an herbal drug used for diabetes) was studied together with its effect against sugar-induced lens opacity in organ culture. Diabecon aqueous extract (DAE) showed potential inhibitory activity with an IC 50 value of 10 μg/ml against rat lens AR. Incubation of goat lens with supraphysiological concentrations of glucose (100 mM) led to the loss of lens transparency associated with increased AR activity, decreased soluble protein and increased protein carbonyls and glycation. Addition of DAE (0.3 mg/ml) to the medium preserved transparency and ameliorated the decrease in lens soluble protein due to hyperglycemia and also prevented the formation of glycated protein. Interestingly DAE inhibited aldose reductase activity in lens incubated with 100 mM glucose. DAE decreased protein carbonyls, prevented the loss of β L-crystallin against 100 mM of glucose. We have also demonstrated here that most of these effects are mainly due to Gymnema sylvestre, one of the constituent herbs of Diabecon. These results suggest that Diabecon protect the lens against sugar-induced cataract by multiple mechanisms.

Effect of ketoacids on H(2)O(2) induced cataract.

Cataract is one of the leading causes of visual disability often leading to blindness in the elderly population. One of the causes is oxidation of proteins present in lens, by hydrogen peroxide (H(2)O(2)). In the present study 100 goat lenses were analyzed to determine the protective efficacy of ketoacids, against the oxidative insult by H(2)O(2). The ketoacids used were (pyruvate, alpha ketoglutarate and oxaloacetate), that are constantly produced endogenously. The lenses were incubated as control and experimental groups in TC-199 media for 72 hrs. H(2)O(2) concentration of 10mM was used to induce cataract. The biochemical parameters measured were levels of malondialdehyde (MDA), a lipid peroxidation product and activity of glutathione peroxidase (G-Px), an enzymatic antioxidant. The results showed a significant increase in the levels of MDA and significant decrease in the activity of G-Px in the cataractous lenses as compared to control. After addition of ketoacids (pyruvate (10mM), alpha ketoglutarate (20mM) and oxaloacetate (20mM)) separately, the levels of MDA decreased significantly and the activity of G-Px increased significantly. The results suggest that the ketoacids can be very promising antioxidants for the treatment of cataract. They may also be useful in treating other disabilities related to acute and chronic oxidative stress.

Interaction of H +-ions with α-crystallin: solvent accessibility of ionizable side chains and surface charge

Interaction of H +-ions with α-crystallin from goat lens has been studied at three different ionic strengths using the potentiometric titration method. Titrations have also been carried out in the presence of 1.5 M and 6 M GuHCl (guanidine hydrochloride). The isoionic pH of the protein in water and the effect of KCl on it have been determined. Titration curves have been found to be reversible between pH 3 to 9.25 at all ionic strengths. To aid in the data analyses, the reactivities of α-crystallin lysine residues to trinitrobenzenesulfonic acid have been determined in this work. For α-crystallin aggregate, 130±2 histidine side chains out of a total of 300 and about 134±4 lysine side chains out of 310 have been found to be inaccessible to the solvent in the native condition. The remaining titratable side chains determine the surface charge of the native protein. In 1.5 M GuHCl, however, the nontitratable histidine side chains are found to be available for titration as are the nontitratable lysine and tyrosine side chains in 6 M GuHCl. The theoretical titration curve computed on the basis of Linderstrøm–Lang model is found to fit quite comfortably with the experimental one between pH 4.6 and 9.25. The p K int value for β, γ-carboxyl side chains has been found to be 5.18 which is somewhat higher than usual indicating that the carboxyl groups in the protein are probably in some constrained condition which is released in the presence of a denaturant. Below pH 4.6, there begins a conformational change in the α-crystallin aggregate as is corroborated from the circular dichroism studies. The value of electrostatic interaction factor w which remains more or less constant between pH 4.6 and 9.25 is also found to gradually fall off below pH 4.6.

SHORT COMMUNICATION: Glutathione S-transferase of goat lens: evidence for expression of only class mu isoenzymes

PURPOSE. It has been suggested that glutathione S-transferases (GSTs) of the mammalian ocular lens detoxify various toxi-cants and cataractogens; therefore, it provides protection against cataractogenesis. In this study the GST isoenzymes of goat lens have been purified and characterized. METHODS. The goat lens homogenate was subjected to affinity chromatography over GSH-linked epoxy activated Sepharose 6B. The isoenzymes of the GST were separated by chromato-focusing on a Mono-P column using FPLC ®. RESULTS. Two GST isoenzymes, GST 7.2 and GST 6.6, were purified to apparent homogeneity from goat lens. GST 7.2 appeared to be a heterodimer of Mr. 26,500 and Mr. 25,000 subunits, the GST 6.6 showed a homodimeric subunit structure of Mr. 25,000. Western blotting and the N-terminal region amino acid sequence analysis indicated that both isoenzymes of goat lens belong to the µ-class GST. CONCLUSIONS. Although they share varying degrees of structural correlation, the two isoenzymes of goat lens seem to be the products of two distinct genes. The isoenzyme expression pat-tern of GST in goat lens is similar to bovine lens, which also contains two isoenzymes belonging only to GST µ.