Kinetic properties of hexokinase as assembled with a microcomputer data base

Abstract

We have constructed a relational data base containing the kinetic properties of the isoenzymes of hexokinase using the Knowledgeman data-base program on an IBM PC microcomputer. The natural subunit of this data base is the refereed publication, 165 of which were included. Reported values for the M(r) (approx. 97,000) are in good agreement, but this agreement becomes progressively worse as one examines the K(m) values for glucose and ATP and the K(i) for glucose 6-phosphate, where the reported values are spread over three orders of magnitude. Some quantities are very thinly or unreliably determined. Experimental conditions, especially free Mg2+ concentration, are rarely close to physiological. Reasons for the spread or uncertainty of numbers, and the distinctions that can be made between isoenzymes despite this spread, are discussed.