Surface activation of pro-cathepsin L.
Pro-cathepsin L is an inactive zymogen that has been shown previously to undergo autolysis at pH 3.0 to give mature forms of the enzyme. We have now been able to demonstrate that this enzyme can undergo activation at pH 5.5 in the presence of negatively charged surfaces. Activation could also be measured at pH 6.0, but no activation occurred at pH 6.5 or higher. The initiation of activation depends upon the presence of a small percentage of active pro-enzyme, and this is then followed by a more rapid activation to give mature forms of the enzyme. No significant intermediate molecular forms of the enzyme were seen. The time taken for processing of the pro-enzyme to single-chain mature enzyme is comparable to that seen in biosynthetic pulse-chase experiments.
Mason
R W
RW
Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg 24061.
Massey
S D
SD
D016475:3T3 Cells; D000818:Animals; D056668:Cathepsin L; D002403:Cathepsins / Q000302:isolation & purification / Q000378:metabolism*; D003546:Cysteine Endopeptidases; D016264:Dextran Sulfate / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008247:Lysosomes / Q000201:enzymology; D051379:Mice; D011499:Protein Processing, Post-Translational
D004792:Enzyme Precursors; D007527:Isoenzymes; D016264:Dextran Sulfate; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D056668:Cathepsin L; C534278:Ctsl protein, mouse