Substrate specificity of glucokinase and fructokinase of several conifer species

Annual plant species were found to have several distinct classes of hexokinases which are specific for different hexoses, such as glucose, fructose and mannose. In conifers one isozyme of hexokinase could be found in genetic studies if only glucose was employed as substrate. If fructose was substituted for glucose, another isozyme zone different from the common hexokinase could be observed in zymograms of extracts from seed tissues of Norway spruce, Scots pine and silver fir. Hence these three conifer species possess at least two different hexokinases, glucokinase and fructokinase.