Structural Biochemistry/Enzyme Regulation/Isoenzyme analysis

The analysis of patterns of selected enzymes has been used extensively as a technique to identify the species of origin of cell lines with a high degree of certainty. Isoenzymes (or isoenzymes) are structurally different forms or the same enzyme. They catalyse the same reaction but have different protein structures. Each cell line would have its own unique array of isoenzymes.

The technique involves gel electrophoresis of cell homogenates under non-denaturing conditions. Specific activity stains are used to develop a banding pattern of isoenzymes (zymogram), which is characteristic of a particular cell line. Such zymograms are usually photographed to provide a permanent record of each cell line.

zymogram of endopeptidase enzyme

Of the various enzymes that can be separated into isoenzymes by this technique, glucose 6-phosphate dehydrogenase, and nucleoside phosphorylase have been particularly well characterised. By using several enzymes the distinguishing features of a cell line are established. These features can often distinguish cell lines even if derived from the same species.