Petr Kuzmic said:
> If an enzyme is embedded in a multienzyme complex or partially buried in the
> membrane itself, I suppose that this must change the structure (tertiary, or
> even secondary) of the protein molecule. I supposed that under those
> circumstances the behavior of the solubilized and immobilized enzyme should
be
> intrinsically different.
An excellent example of this is fatty acylCoA synthetase, which catalyzes a
two-step esterification reaction.
FA + MgATP = FA-PP-Mg + AMP
FA-PP-Mg + CoASH = FA-SCoA + MgPPi
[FA is the fatty acyl moiety, and PP is pyrophosphate.] This protein is
embedded in the endoplasmic reticulum with its catalytic site facing the
cytosolic space. Purification of the enzyme results in an inactive protein.
Apparently, either the enzyme is composed of several peptide chains which
dissociate on purification or the protein must be held in an active
conformation by being partially buried in a phospholipid micelle.
--
Michael C. Kohn
Laboratory of Computational Biology and Risk Analysis
National Institute of Environmental Health Sciences
P.O. Box 12233, Mail Drop A3-06
Research Triangle Park, NC 27709-2233
Telephone:
919-541-4929 (voice)
919-541-1479 (fax)
e-mail:
kohn at valiant.niehs.nih.gov
WWW home page:
http://valiant.niehs.nih.gov
