Proteasis

[2810712]

The P of P

Proteases are not digested by themselves or other proteases. This implies that the factor leading to their specificity for substrate is not just the peptide linkage but something more...what is it?
Does any body know? Or if this is not correct then pH might be the reason- that is some substrate resides in low pH area where some proteases won't act or any other chara. like pH
BUt if the pH is the specific chara. then still the problem of self digestion remains to be solved...

[Ultrashogun]

Good question. Something related and also interesting is that the sc Prion is more resistent to proteasis than the c one.

[tranjo]

I've never looked at the sequences for proteases, but might there be an accessibility problems for proteases as well? To clarify, might a serine protease not find serines on another protease, or another serine protease? It would be evolutionary favorable to protect oneself from these rogues.

So maybe a combination of pH, structure accessibility, isolation within a cell, and the requirement of other co-factors is the key.

Here's a funny scenario, could a protease being translated (assuming that it adopts active structure based only on sequence) digest the ribosome it's translated from? And come to think of it, when a cell translates an RNase, does it immediately turnover the RNA going through a ribosome? RNases are notorious creatures with little dependency on cofactors and secondary structures that are stable!

These are interesting questions, and probably ones that might be worth a paper in a journal with a high impact factor (>20)!! BLAH!

Best, J

[2810712]

Hey thanks for the the qs u put forward really interestin!
So who's gonna do it first! [the paper publsihment?]

[tranjo]

Even better, how do you test this!?!?

Best, J

[Poison]

Can this discussion be what you're searching for?
Actually, they do digest themselves.

viewtopic.php?t=1249

[tranjo]

Hi Poison,

What you sent is interesting, and thanks for it. I spent the last hour looking at hydrolases!

However, I think the RNases are a special case. A protease probably needs some other factor to perform, so a regulatory mechanism probably exists preventing it from going bonkers on ribosomes and other cellular proteins. RNases are tricky because they are so independent (isn't this why they're such a pain?) and quite resillient. I think it would be interesting to find out what secret life an RNase lives as it's translated! And what needs to be done to prevent it from going bonkers on RNA! Thanks for the brain-food.

Best, J

PS, enzymes aren't always proteins! Thomas Cech and Sidney Altman have Nobels for that!

[2810712]

thanks poison that's the same. from there it becomes clear that it might be the mechanism to keep protease activity under control. But i wonder that it is also not impossible that not all proteases use this self-control mechanism...just a point that the evolution of each protease popullation from each protease type is independent of that of other proteases...mostly.

[2810712]

Hi Poison,

What you sent is interesting, and thanks for it. I spent the last hour looking at hydrolases!

However, I think the RNases are a special case. A protease probably needs some other factor to perform, so a regulatory mechanism probably exists preventing it from going bonkers on ribosomes and other cellular proteins. RNases are tricky because they are so independent (isn't this why they're such a pain?) and quite resillient. I think it would be interesting to find out what secret life an RNase lives as it's translated! And what needs to be done to prevent it from going bonkers on RNA! Thanks for the brain-food.

Best, J

PS, enzymes aren't always proteins! Thomas Cech and Sidney Altman have Nobels for that!

umm...yeah man that's a thing. THis prob about DNAase won't occur in eukaryotes as the DNAs ain't exposed to DNAases....but in prokaryotes...
also we shouold also think of negative feedback mechanisms n=might exists for RNAases,...

VEd