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Proteolytic enzymes
About: Proteolytic enzymes is a research topic. Over the lifetime, 23096 publications have been published within this topic receiving 835544 citations.
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TL;DR: It is suggested that the sialoglycoprotein and the 35K segment of the 95K protein are not involved directly in anion permeation, and the most likely location of the inhibitory site is in a portion of the 65K segment, exposed to the outside surface.
220 citations
TL;DR: Findings suggest that the full activity of ribonuclease, in the presence of such denaturing agents, is due to a refolding of the protein under the influence of Ribonucleic acid.
220 citations
TL;DR: It is suggested that corticosteroid treatment of asthma can reduce subepithelial collagen deposition by downregulation of MMP-9 expression and upregulation of TIMP-1 expression.
Abstract: Background: Bronchial asthma is characterized by airway wall remodeling. Matrix metalloproteinases (MMPs) are members of a family of proteolytic enzymes that degrade the extracellular matrix and that restrain the effects of their tissue inhibitors (TIMPs). Treatment with inhaled corticosteroids may prevent airway remodeling in asthma. However, the effects of corticosteroid treatment on MMPs and TIMPs in asthma are unknown. Objective: We examined the effects of inhaled beclomethasone dipropionate (BDP) on the expression of MMP-9 and TIMP-1 and subepithelial collagen deposition in bronchial biopsy specimens from 30 subjects with asthma. Methods: Inhaled BDP, 800 μg daily, or placebo was administered for 6 months in a double-blind, parallel-group study, and bronchial biopsies were performed before and after treatment. Biopsy specimens were examined for extent of collagen type III in the subepithelial basement membrane by means of immunohistochemistry, and expression of both epithelial and submucosal MMP-9 and TIMP-1 was quantitated. Numbers of inflammatory cells were also determined. Results: We observed significant decreases in collagen type III deposition ( P P P r s = 0.37, P r s = 0.47, P Conclusion: Our findings suggest that corticosteroid treatment of asthma can reduce subepithelial collagen deposition by downregulation of MMP-9 expression and upregulation of TIMP-1 expression. (J Allergy Clin Immunol 1999;104:356-63.)
219 citations
Journal Article•
TL;DR: Levels of cathepsins B and G are increased in corneas with keratoconus, suggesting that these enzymes may contribute to the heightened in situ gelatin- and casein-digesting activities, leading to abnormalities in keratconus.
Abstract: Purpose Keratoconus is characterized by thinning and scarring of the central region of the cornea. Previous research showed that, in corneas obtained from patients with keratoconus, lysosomal enzyme activities are elevated, whereas levels of protease inhibitors such as alpha1-proteinase inhibitor are reduced. This study was undertaken to examine further the expression of a spectrum of proteolytic enzymes and protease inhibitors. Methods Corneal buttons were collected from patients with keratoconus, healthy subjects, and patients with other corneal diseases. Immunohistochemical staining was performed on paraffin sections. Enzymatic assays and western blot analysis were carried out for cathepsins B and G. In addition, an in situ zymography procedure was used to examine the gelatin- and casein-digesting activities in corneas with keratoconus. Results An enhanced staining was found with antibodies to cathepsins B and G. Enzymatic assays and western blotting confirmed that the levels of these two enzymes were elevated in corneas with keratoconus. No alteration was noted with any of the matrix metalloproteinase (MMP) family members and other enzymes and inhibitors examined, although in situ zymography did indicate an increase in net gelatin- and casein-digesting activities in corneas with keratoconus. These activities were mostly abolished by inhibitors for serine and cysteine proteinases, but not by those for MMPs and aspartic proteinases. Conclusions Levels of cathepsins B and G are increased in corneas with keratoconus. These enzymes may contribute to the heightened in situ gelatin- and casein-digesting activities, leading to abnormalities in keratoconus.
219 citations
TL;DR: The data are consistent with the hypothesis that proteasome is progressively inhibited by small accumulations of oxidized and cross‐linked proteins during proliferative senescence until late proliferation stages, when so much proteasomes activity has been lost that oxidized proteins accumulate at ever‐increasing rates.
Abstract: Oxidized and cross-linked proteins tend to accumulate in aging cells Declining activity of proteolytic enzymes, particularly the proteasome, has been proposed as a possible explanation for this phenomenon, and direct inhibition of the proteasome by oxidized and cross-linked proteins has been demonstrated in vitro We have further examined this hypothesis during both proliferative senescence (this paper) and postmitotic senescence (see the accompanying paper, ref 1⤻) of human BJ fibroblasts During proliferative senescence, we found a marked decline in all proteasome activities (trypsin-like activity, chymotrypsin-like activity, and peptidyl-glutamyl-hydrolyzing activity) and in lysosomal cathepsin activity Despite the loss of proteasome activity, there was no concomitant change in cellular levels of actual proteasome protein (immunoassays) or in the steady-state levels of mRNAs for essential proteasome subunits The decline in proteasome activities and lysosomal cathepsin activities was accompanied by d
219 citations