Just to be a pedantic pain - Km is not necessarily Kd. I think that assumption only holds if the chemical step following substrate binding is rate-limiting. Phoebe
---- Original message ---- >Date: Mon, 1 Dec 2008 15:34:59 +0100 >From: mesters <[EMAIL PROTECTED]> >Subject: Re: [ccp4bb] co-crystallization >To: CCP4BB@JISCMAIL.AC.UK > >Yes!, there is: > >the fraction of occupied protein with substance can be calculated: S / >(S + Km) with S being the concentration of the compound. > >So, if S = Km, half of the sites are occupied (it follows from >Michaelis-Menten theory). > >In order to saturate the enzyme for 90,90909 % with the compound: > >1) S = 10 x Kd (concentration of S at least 10 times the Kd) >and >2) S > P (total concentration of S must be larger than total >concentration of protein or "binding sites") > >Depending on the solubility of the compound, this is not always >possible. In such a case, you need to use DMSO and/or add solid compound >to the protein solution and leave it for quite some time for the >compound to finally bind to the protein. > >- J. - > > >yangliuqing wrote: >> Hello,everyone, >> I have a question for cocrystallization, is there some relationship >> between Km value and substrate concentration when making >> cocrystallization? How can I know the substrate is enough for binding? >> Thank you very much! >> liuqing >> >> ------------------------------------------------------------------------ >> 八卦娱乐包打听，MSN资讯速递帮你忙！ 了解详细！ >> <http://im.live.cn/newsexpress> > > >-- >Dr. Jeroen R. Mesters >Gruppenleiter Strukturelle Neurobiologie und Kristallogenese >Institut für Biochemie, Universität zu Lübeck >Zentrum für Medizinische Struktur- und Zellbiologie >Ratzeburger Allee 160, D-23538 Lübeck >Tel: +49-451-5004065, Fax: +49-451-5004068 >Http://www.biochem.uni-luebeck.de >Http://www.iobcr.org >Http://www.selfish-brain.org >Http://www.opticryst.org >-- >If you can look into the seeds of time and say >which grain will grow and which will not - speak then to me (Macbeth) >-- Phoebe A. Rice Assoc. Prof., Dept. of Biochemistry & Molecular Biology The University of Chicago phone 773 834 1723 http://bmb.bsd.uchicago.edu/Faculty_and_Research/01_Faculty/01_Faculty_Alphabetically.php?faculty_id=123 RNA is really nifty DNA is over fifty We have put them both in one book Please do take a really good look http://www.rsc.org/shop/books/2008/9780854042722.asp
