Re: Re: "Carn." Bromeliads

Jan Schlauer (Jan@pbc-ths1.pci.chemie.uni-tuebingen.de)
Fri, 23 Feb 1996 09:27:11 +0100

Dear Dave,
>> Mime-Version: 1.0
>
>What is this "Mine-Version" stuff? Every message from you has a
>whole page of this.

It is "Mi*m*e". This is a means to encode non-ASCII characters (like the
German umlauts). But as this did not always produce satisfactory results
(people who received my messages got nonsense and not umlauts), I do
generally not use umlauts etc. in my emails.

>> single species. I agree that they (and rather numerous other plants)
>> approach it to some degree. This can IMHO be expressed appropriately by the
>> term "sub-carnivorous".
>
>Jan or anyone, how does one go about testing CP's for digestive
>enzymes in Sarracenia? Since I've got them all and many hybrids
>I think I should test them.

You need an enzymatic assay. The most simple type is a photometric test
(for which you need a photometer). You mix a hydrolyzable dye (chromogenic,
i.e. one which becomes a dye upon hydrolysis, e.g.
L-Aminoacyl-beta-napthylamide) with the "digestive" fluid and let it act
for several minutes. After this time you determine the absorbance
(extinction) of this test assay against a (negative) control which included
distilled water instead of "digestive" fluid. To veryfy the results you can
add a protease (e.g. pepsin) to the assay as a positive control. Most tests
of this kind do only check hydrolytic activity (i.e. not necessarily
specifically proteolytic) but this is in most cases suffigient for the
assumption that at least some enzymes are secreted.

A classical method is measuring the hydrolysis of casein (disappearance of
solid protein). But as incubation lasts at least for several hours
(sometimes days), results are somewhat menaced by microbial infection.

> If the plant produces the enzymes
>*after* proteins are added, how do you avoid bacterial enzyme
>production?

This can only be avoided by sterile test conditions.

>Or is this false, do un-opened pitchers also
>supposedily to contain enzymes?

Yes, _Sarracenia_ has the hydrolytic activity supposedly in unopened
pitchers already, so you need not to stimulate secretion by the addition of
proteins.

Kind regards
Jan