[Protein-analysis] Re: serine protease inhibition by plastic extractable material

ChenHA via proteins%40net.bio.net (by hzhen At freeuk.com)
Mon Nov 20 11:57:07 EST 2006


On Mon, 20 Nov 2006 02:14:24 GMT, dk At no.email.thankstospam.net (DK)
wrote:

>In article <1163981995.186709.246890 At b28g2000cwb.googlegroups.com>, "rolando" <rolando.perdomo At infomed.sld.cu> wrote:
>>Hi  Every one,
>>
>>I found that during preparation of cellular extract to analyze serine
>>protease activity, if sample is sonicated in 1.5 ml eppendorf centrigue
>>tubes, the proteolytic activity is diminished. In other hand, if the
>>same cells are lysed by sonication using a glass reservoir no
>>inhibition appears. Does anyone know about relation of protease
>>inhibition and plastic-extractable material??? References????? Looking
>>forward to receive some light.
>
>
>Bad experiment. If you were to blame plastic-extractables, you should 
>be able to get inhibition by sonicating buffer in the eppy and adding it
>to you protease. 
>
>If both sonications are done on ice, the more likely explanation is
>that heat dissipation is too slow in plastic => protein heats up too
>much => activity is diminished due to partial denaturation. 
>

I think it is bad idea to sonicate in an eppendorf tube because it
does get very hot very quickly.  Having said that, I don't know what
size the glass reservoir is and how it compare in terms of heat
dissipation.  Another thing to consider however is that we do know
that many proteins do bind to plastic (or indeed glass).  Perhaps it's
a combination of things.


>DK



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