From owner-metabolic-reg@net.bio.net Mon Oct 18 23:00:00 1993 Path: biosci!daresbury!doc.ic.ac.uk!pipex!uknet!festival!castle.ed.ac.uk!eanv20 From: eanv20@castle.ed.ac.uk (John Woods) Newsgroups: bionet.metabolic-reg Subject: Rate limiting step (Was: Interested Bystander) Message-ID: Date: 19 Oct 93 12:08:09 GMT Sender: news@festival.ed.ac.uk (remote news read deamon) Organization: Edinburgh University Lines: 29 Posted on behalf of David Fell ---------------------------------------------------------------------- I don't agree with Benno ter Kuile (terkuile@edu.rockefeller.rockvax) that re relaxation of the definition of `rate-limiting' to be 75% or more of the flux control really helps. Most people who use `rate-limiting step' have no quantitative experimental information about the degree of influence of the step on pathway rate at all. Usually they just mean that they've decided it's a very important step, and the experimental information they cite, if any, does not allow a quantitative assessment. Can Benno give an example of a user of the `rate-limiting step' concept who can claim justification by a published demonstration of a flux control coefficient greater than 0.75? The harm resides in using a term that makes a very specific claim in the absence of experimental results that support its validity, and that's not sloppy use of language, it's bad science. David Fell daf@bms.brookes.ac.uk ---------------------------------------------------------------------- -- " Forsan et haec olim meminisse iuvabit (Virgil) [approx] Tr: The time may come when we will look back on these days and laugh " .