help on lysossomes

Nuno Martins elitro at
Mon Mar 27 07:22:31 EST 1995

        I'm a portuguese high school biology teacher. Some time ago, a
student of mine put me a question to wich I'm having some trouble finding
a suitable answer. 

        1- Since hydrolases packed in lysossomes are isolated from
cytosdol by a single membrane,which contains lipids,Glycids and
proteins,why do these hydrolases (including lypases,glycolases and
proteases) do not destroy these membrane? All the books I searched just
ommited this particularity,or said that nothing is known about this. In
"Molecular Biology of the Cell" I found there was a relationship between
the high glycosilation of lysossomic membranes, and their
indestructibility but this is just too vague to be able to clarify me (or 
anybody else for that matter). 

       2- Since the lysossomic hydrolases only act at low pH values, how 
do they perform autolysis of the cell(the cytosol pH is about 7.2,I believe)?
Once again i couldn't even find the topic autolysis in my books,so, 
information was, again, inexistant.

       Thank you in advance,any answers will be welcome.

       My best regards,

             Nuno de Oliveira Martins
             Performing probation at
             Sciences College - University of Lisbon
             Lisbon - Portugal 

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