Modified prokaryotic glucose isomerase enzymes with altered pH activity profiles

US5340738A · kind A · utility

Assignees

• Gist-Brocades N.V. · NL
• Plant Genetic Systems N.V. · BE

Inventors

• Anne-Marie Lambeir · Heverlee, BE
• Ignace Lasters · Ekeren, BE
• Nadir Mrabet · Koekelberg, BE
• Wilhelmus J. Quax · Voorschoten, NL
• Jan Metske Van Der Laan · Echt, NL
• Onno Misset · Delft, NL

Key dates

• Filing date: Jan 4, 1991
• Grant date: Aug 23, 1994
• Expiry date: Jan 4, 2011

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C12N9/92
• WIPO field: Biotechnology
• WIPO sector: Chemistry

Abstract

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.