Hexokinases are enzymes that phosphorylate cellular hexoses, creating hexose phosphates. One major substrate of hexokinase is glucose, creating the product glucose-6-phosphate, a compound with a variety of fates such as glycolysis. Abnormal hexokinase activity has been implicated in a number of human diseases states such as cancer and diabetes. Efforts to design drugs to target only one errant hexokinase isozyme have proved unsuccessful due to the amino acid sequence similarities among hexokinases, hence the need for more information on the structural differences on isozymes.<br/><br/>In this study, yeast hexokinase I (HxKI) from the single-celled bread yeast Saccharomyces cerevisiae was used to model the monomeric human hexokinase isozyme IV or glucokinase. A computer model was then used to predict which residues of HxKI are most important to the stability of substrate binding to catalytic function. These predictions were then used to engineer site-specific mutation in the DNA of HxKI in order to substitute amino acids and alter function of the enzyme.<br/><br/>Altered forms of the isozyme will be used in thermodynamic ligand-binding studies in order to examine the relationship between hexokinase structure and function. Comparisons of the ligand binding strengths of wild type and mutated hexokinase will provide a better understanding of the subtle structural differences between isozymes, enhancing the ability to create inhibitors specific to one isozyme without adversely affecting the other.

Mutation of yeast hexokinase I for structure-function analysis

249th National Meeting (2015)

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