Gist-brocades N.v.

Plant Genetic Systems N.v.

Plant Genetic Systems

Plant Genetics System, Nv

Genencor International, Inc.

Nadir Mrabet

Wilhelmus J Quax

Ignace Lasters

Jan Metske Van Der Laan

Onno Misset

Anne-Marie Lambeir

Wilhemus J Quax

Rudolf Gm Luiten

Patrick Stanssens

Paul W Schuurhuizen

Shoshana Wodak

Gaston Matthyssens

Wilhelmus Johannes Quax

A method for selecting amino acid residues is disclosed which upon replacement will give rise to an enzyme with an altered pH optimum. The method is specific for metalloenzymes which are inactivated at low pH due to the dissociation of the metal ions. The method is based on altering the pK.sub.a of the metal coordinating ligands or altering the K.sub.ass for the metal binding. New glucose isomerases with an altered pH optimum are provided according to this method. These altered properties enable starch degradation to be performed at lower pH values.

Glucose isomerases with an altered pH optimum

New mutant glucose isomerases are provided exhibiting improved properties under application conditions. These glucose isomerases are obtained by expression of a gene encoding said enzyme, having an amino acid sequence which differs at least in one amino acid from the wildtype glucose isomerase. Preferred mutant enzymes are those derived from Actinoplanes missouriensis glucose isomerase.

Glucose isomerase enzymes and their use

Modified prokaryotic glucose isomerase enzymes with altered pH activity

The invention pertains to a method for the production of a biologically active modified protein derived from a starting protein having essentially the same kind of biological activity with an attendant modulation effect on, particularly increase of, the stability as compared with that of the starting protein. The method comprises substituting an arginine residue for a lysine residue of the starting protein at a site that can sterically accommodate the substitution, without substantially altering the biological activity of the starting protein, said site being preferably of low solvent accessibility, at interfaces between domains or sub-units of the starting protein.

Methods and means for controlling the stability of proteins

Growing community of inventors

Hoeilaart, Belgium

Nadir Mrabet