Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.5 (cathepsin D)
 4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The desirable fixation conditions for the histochemical demonstration of cathepsin D using mercury-labeled pepstatin as an enzyme inhibitor were examined biochemically and histochemically. Four well known fixatives, namely, glutaraldehyde (GA), paraformaldehyde (PFA), glutaraldehyde with paraformaldehyde (GA-PFA) and periodate-lysine-paraformaldehyde (PLP), were applied to the prefixation of tissues prior to the reaction of the labeled inhibitor to the enzyme-active site. The effects of fixatives on cathepsin D were biochemically examined using subcellular fractionated lysosomes. Cathepsin D from rat liver lysosomes was rapidly inactivated by the fixatives containing glutaraldehyde, i.e., GA and GA-PFA, whereas the activity of cathepsin D was sufficiently maintained after fixing the enzyme in the PFA or PLP preparations. Effects of the PLP fixative on lysosomal cathepsin D in liver tissues using the mercury-labeled pepstatin method were also studied histochemically. The best result for the visualization of lysosomal cathepsin D in liver tissues was obtained using the PLP fixative with the prefixation time of three hours or more.
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PMID:An improved procedure for the histochemical demonstration of cathepsin D by the mercury-labeled pepstatin method. 620 30

Pepstatin, a specific inhibitor of pepsin, cathepsin D (E), renin, etc., was used in a new method to demonstrate the sites of enzymes. Pepstatin (Pst) was covalently attached to glutathione (GSH), using a dicyclohexylcarbodiimide, and CH3Hg+ was then put in the residue of SH for electron microscopic observation. Pst-GS-HgCH3 thus obtained was nonisotopical, had a very low molecular weight (about 1,200 daltons), and still almost completely retained its inhibitory activity. Sections of rat liver (less than 1 mm3 thick), prefixed by glutaraldehyde, were incubated in the prepared reaction medium. Cathepsin D, located in the lysosomes, was demonstrated by this compound, but when the sections were preincubated with pepstatin, this was not the case. These results demonstrate that mercury-labeled pepstatin is a useful reagent for the histochemical staining of acid proteases for electron microscope.
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PMID:Electron microscopic visualization of cathepsin D using mercury-labeled pepstatin as an enzyme inhibitor. 715