English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Assay conditions were elaborated to determine the catalytic activity of cathepsin S fluorometrically for direct comparison with the activities of cathepsins B + L(+S) and B along the nephron of the normal rat. These conditions include the use of 0.5 mM Z-Phe-Arg-AMC as substrate, which is saturating for the three enzymes. The stability of cathepsin S at pH 7.5 and the resistance of cathepsin B against inactivation by 0.5 microM Z-Phe-Phe-CHN2 permitted differentiation of these enzyme activities. The catalytic activity of cathepsin S in rat kidney homogenate (1.11 mumol/min x g protein) amounted to 2.1% of that of cathepsins B + L(+S) and to 3.2% of that of cathepsin B. It was ten-fold higher in the cortex (1.54 mumol/min x g protein) than in the medulla resembling the activity ratio of cathepsins B + L(+S) and B. In suspensions of isolated glomeruli and isolated proximal tubules the activities of cathepsin S were 0.76 and 3.21 mumol/min x g protein, respectively. The corresponding activities of cathepsins B + L(+S) amounted to 80.0 and 211.7 mumol/min x g protein consisting of 71% cathepsin B activity. In nephron segments microdissected from lyophilized renal sections, highest cathepsin S activity was found in the proximal convoluted tubules (4.21 mumol/min x g dry weight) followed by 0.83 mumol/min x g dry weight in proximal straight tubules of the superficial cortex. In the remaining segments cathepsin S activity was hardly detectable. Unlike cathepsin S activity, the activity of cathepsin B was distributed in parallel to that of cathepsins B + L(+S). The presence of relatively high cathepsin S activity in proximal convoluted tubules in co-localization with the activities of cathepsins B + L(+S) and B suggests a primary role of these enzymes in heterophagocytosis of proteins from the ultrafiltrate.

Specific Catalytic Activity of Cathepsin S in Comparison to Cathepsins B and L along the Rat Nephron