Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although xerophthalmia due to severe vitamin A deficiency is the leading cause of childhood blindness in the underdeveloped countries, little is known about the proteases (other than collagenase) that are involved in the degradative mechanism. The degree of cellular autolysis and stromal degradation observed histologically in early stages of xerophthalmia and in ulcerating corneas in vitamin A deficient rabbits in this study were, in general, proportional to the levels of the proteases studied. The only major histologic and ultrastructural alteration observed in early xerophthalmic corneas was autolysis of superficial epithelial and stromal cells. In contrast, in the ulcerating corneas the stroma was infiltrated heavily with inflammatory cells and extensive stromal degradation was observed in the central necrotic region of the lesions. Maximal proteolytic activity toward hemoglobin was observed at pH 3.3 for corneal extracts from normal (N) and pair-fed control (C) rabbits and rabbits with early xerophthalmia (X) and ulcerating xerophthalmia (U) corneas. This activity was a cathepsin D-like enzyme per cornea that had a ratio of 1:1:3:16 in the N, C, X, and U corneas. The ratio of cathepsin B-like activity per cornea for N, C, X, and U corneas was 1:2:2:10.
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PMID:Acid proteases and histologic correlations in experimental ulceration in vitamin A deficient rabbit corneas. 388 66

A mild trauma in the form of a thermal burn was applied to corneas of vitamin A--deficient rats and their pair-fed controls. The control corneas routinely showed rapid re-epithelialization without stromal changes. The corneas of deficient rats recovered more slowly, frequently exhibiting stromal edema, leukoma, and sometimes ulceration. Because collagenase is thought to initiate collagen destruction in corneal ulceration, the relationships among vitamin A status, severity of trauma, and collagenase levels were determine. Mild thermal burns were found to cause corneas from less severely deficient rats to ulcerate rarely but no release increased levels of collagenase, mainly on the first day of culture, as in the case of nonburned, severely deficient rats. Comparable burns of corneas of pair-fed control rats resulted in no ulceration and in very little collagenase release. Severe burns of either pair-fed control or normal rat corneas caused ulceration and collagenase release, but collagenase activity was maximal on the second and third days of culture. Differences in vitamin A status at time of burning gave rise to different patterns of collagenase. By following the development of the vitamin deficiency, it was determined that little active collagenase is released after mild burns of corneas in animals in the pre--weight plateau stage but that much more active enzyme is released when animals are in weight plateau or 5% weight loss stages. Studies of the effect of recovery from vitamin A deficiency on the response to mild thermal burn indicated that the longer the interval between feeding vitamin A and the burn, the lower the postburn level of collagenase in the day 1 medium. Thus it would appear that restitution of vitamin A status decreased the level of active collagenase after the mild thermal burn. The system developed here can be used to study the biochemical basis for ulceration in vitamin A deficiency, and the possibility exists that the ulceration characteristic of keratomalacia in people can be initiated by an environmental trauma.
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PMID:The effect of thermal burns on the release of collagenase from corneas of vitamin A--deficient and controls rats. 625 3

Non-specific carboxylesterases (carboxylesterases) and glutathione S-transferases (GSTs) are two groups of drug metabolizing enzymes responsible for hydrolysis and glutathione conjugation of xenobiotics. This study was conducted to determine the following: (1) the distribution of carboxylesterase and GST activities in different rat liver cells, (2) the effects of vitamin A deficiency (A-) on the absolute activities and on the distribution of carboxylesterases and GSTs in rat liver. Rat livers were fractionated into parenchymal and non-parenchymal cells by means of collagenase perfusion and differential centrifugation. Non-parenchymal cells were further fractionated by means of Percoll density gradient centrifugation into a layer of Kupffer cells and another layer containing stellate and endothelial cells. Carboxylesterase and GST activities were determined in these fractions. show that: (1) both carboxylesterases and GSTs were mainly localized in the parenchymal fraction, (2) there was no significant difference between male and female rats with regard total activity or distribution of carboxylesterases and GSTs in rat liver cells, (3) A- caused a highly significant reduction in carboxylesterase and GST activities in total liver homogenates and parenchymal cells. This reduction was not ameliorated by administration of retinoic acid 18 hr before sacrifice of animals. These results open up a new era of investigations about the potential role of vitamin A in the regulation of detoxification enzymes.
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PMID:The distribution of non-specific carboxylesterases and glutathione S-transferases in different rat liver cells. Effects of vitamin A deficiency. 804 15