>I mean multienzyme proteins. Thank you. JDP.
>>At 03:49 PM 6/6/96 +0000, you wrote:
>>>Hello!
>>>>>>Are there any references out there for multifunctional enzymes?
>>>>>>Thanks! Please email to: pollack.1 at osu.edu>>>>What do you mean by "multifunctional enzymes"? There are various
>>answers one could give, depending on whether you mean unspecific
>>enzymes (as suggested in Paul M. Schlosser's reply), or multienzyme
>>proteins (for example aspartokinase/homoserine dehydrogenase in
>>bacteria).
>>The references I have are not very up-to-date, so probably it's best to
suggest some places to look rather than give references to papers from 15
years ago.
Some examples:
Aspartokinase/homoserine dehydrogenase from E. coli (higher organisms tend
to have separate proteins. I think the original work was done by Georges
Cohen, Jean-Claude Patte and others around the end of the 1960s.
Pyruvate dehydrogenase complex. Here I would look for recent articles by
Richard Perham. I don't know of a recent review by him, but it's quite
likely one exists. He is still working on this and has done so for a good
many years. His web page at
http://www.bio.cam.ac.uk/dept/biochem/UTOs/Perham.html contains some
information and references.
The arom multienzyme polypeptide of Neurospora crassa catalyses (if I
remember correctly) five different reactions. Look for articles/reviews by
John Coggins. I think Rickey Welch worked on this also a long time ago, but
I don't think he does now.
Tryptophan synthase exists in various states in different organisms,
sometimes as a multienzyme protein. A review by Huetter et al. in Ann. Rev.
Microbiol. (1986) 40, 57 is probably useful (I haven't looked at it
recently), and there are probably more recent ones. Look also for papers by
Kasper Kirschner.
There has always been some argument about how permanent a complex needs to
be in order to count. Some, like aspartokinase/homoserine dehydrogenase are
a single polypeptide and the reactions catalysed are not consecutive in the
pathway (so there is no question of the experimenter classifying one
reaction as two or more that are not really separate) but others are more
borderline. And there is lots of reason to believe that many supposedly
soluble cytoplasmic enzymes do not exist as separate entities in the cell
under physiological conditions, and so many complexes may exist that are
not considered to be such in classic biochemistry texts. If this sort of
thing interests you you are likely to be interested in the Gordon
Conference referred to by Doug Kell (dbk at aber.ac.uk) in his message of 10th
May to this Newsgroup. Channelling of intermediates in short-lived
complexes has been rather a controversial issue (in which Doug and I have
not always been on the same side): some would regard this as a
manifestation of multienzyme proteins; others not.
Regards,
Athel
================================================================
Athel Cornish-Bowden
Laboratoire de Chimie Bacterienne
Centre National de la Recherche Scientifique
31 chemin Joseph-Aiguier
B.P. 71, 13402 Marseille Cedex 20
France
Phone: + 33 91 16 41 38
Fax: + 33 91 71 89 14
Email: athel at ir1cbm.cnrs-mrs.fr
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Home page: http://ir2lcb.cnrs-mrs.fr/lcbpage/athel/home_page.html
or http://193.50.234.64/lcbpage/athel/home_page.html
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