From owner-metabolic-reg@net.bio.net Wed Jun 05 23:00:00 1996 Path: biosci!IR1CBM.CNRS-MRS.FR!athel From: athel@IR1CBM.CNRS-MRS.FR (Athel Cornish-Bowden) Newsgroups: bionet.metabolic-reg Subject: Re: enzymes Date: 6 Jun 1996 09:04:26 -0700 Organization: BIOSCI International Newsgroups for Molecular Biology Lines: 83 Sender: daemon@net.bio.net Distribution: world Message-ID: NNTP-Posting-Host: net.bio.net >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@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@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@ir1cbm.cnrs-mrs.fr (The character after @ir is a one, not an ell) Home page: http://ir2lcb.cnrs-mrs.fr/lcbpage/athel/home_page.html or http://193.50.234.64/lcbpage/athel/home_page.html (The character after //ir2 is an ell, not a one, likewise after mrs.fr/) .