From owner-metabolic-reg@net.bio.net Tue Apr 20 23:00:00 1999 Path: biosci!newshost.lanl.gov!awabi.library.ucla.edu!128.32.206.55!newsfeed.berkeley.edu!dispose.news.demon.net!demon!newspeer.clara.net!news.clara.net!nntp.news.xara.net!xara.net!server6.netnews.ja.net!daresbury!not-for-mail From: Athel Cornish-Bowden Newsgroups: bionet.metabolic-reg Subject: Re: rate limiting vs rate determining Date: 20 Apr 1999 09:23:48 +0100 Organization: Daresbury Laboratory, Warrington, U.K. Message-ID: <7fhdik$5mi$1@mserv2.dl.ac.uk> NNTP-Posting-Host: localhost.dl.ac.uk X-Trace: mserv2.dl.ac.uk 924596629 5844 127.0.0.1 (20 Apr 1999 08:23:49 GMT) X-Complaints-To: newsmaster@dl.ac.uk NNTP-Posting-Date: 20 Apr 1999 08:23:49 GMT Original-To: btk-mca@dl.ac.uk X-Sender: cornish@ibsm.cnrs-mrs.fr Lines: 29 Jeremy Murray asked: >This is a simplistic question, but I have read conflicting views on the >matter. > >Is there a difference between a rate determining step and a rate >limiting step? >I'm grateful of any information/references/websites > Although one can imagine ways in which these terms might be distinguished, my impression is that no distinction is made in practice, i.e. virtually everyone treats them as synonymous. Of course, in metabolic control analysis you will find that most people feel that both refer at best to an oversimplification or even to a complete myth. The same is probably true to a large extent in chemical (and enzyme) kinetics: W. J. Ray and colleagues showed some time around 1980 (in Biochemistry, I think, but it may have been J. Biol. Chem.) that most mechanisms had no unique rate-limiting step. Athel Email: athel@ibsm.cnrs-mrs.fr Site map: http://ir2lcb.cnrs-mrs.fr/~athel/sitemap.htm New Beer in an Old Bottle: http://ir2lcb.cnrs-mrs.fr/~athel/buchner.htm MCA FAQ: http://ir2lcb.cnrs-mrs.fr/~athel/mcafaq.htm MCA chapter from my book: http://ir2lcb.cnrs-mrs.fr/~athel/mcai.htm .