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Kinetic properties of hexokinase as assembled with a microcomputer data base
L Garfinkel1, D Garfinkel, P Matsiras
1Department of Computer Science, University of Pennsylvania, Philadelphia 19104.
The Biochemical Journal
|June 1, 1987
Summary
This study compiled kinetic data for hexokinase isoenzymes, revealing significant variability in reported values for Km and Ki, highlighting experimental condition impacts.
Area of Science:
- Biochemistry
- Enzymology
- Computational Biology
Background:
- Hexokinases are crucial enzymes in glucose metabolism.
- Isoenzymes of hexokinase exhibit distinct kinetic properties.
- A comprehensive database is needed to consolidate existing kinetic data.
Purpose of the Study:
- To construct a relational database of hexokinase isoenzyme kinetic properties.
- To analyze the variability and reliability of reported kinetic parameters.
- To assess the influence of experimental conditions on kinetic data.
Main Methods:
- Utilized the Knowledgeman data-base program on an IBM PC microcomputer.
- Compiled data from 165 peer-reviewed publications.
- Systematically extracted and organized kinetic parameters (Mr, Km, Ki).
Main Results:
- Molecular weight (Mr) values showed good agreement across studies.
- Michaelis constants (Km) for glucose and ATP, and inhibition constants (Ki) for glucose 6-phosphate exhibited wide variations (up to three orders of magnitude).
- Experimental conditions, particularly free Mg2+ concentration, were often non-physiological.
Conclusions:
- Significant discrepancies exist in reported kinetic data for hexokinase isoenzymes.
- The reliability of certain kinetic parameters is questionable.
- Understanding these variations is crucial for distinguishing between isoenzymes and for accurate physiological interpretation.