Purification and Study of Phosphoglucose Isomerase in Cauliflower

Phosphoglucose isomerase (PGI), an important enzyme in the glycolytic pathway, catalyzes the conversion of glucose-6-phosphate to fructose-6-phosphate and vice versa. The purpose of this research was to isolate PGI from cauliflower using a shortened procedure through column chromatography and characterize it through absorbance readings, enzyme activity measurements, and SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis). PGI was successfully isolated from cauliflower using ion-exchange chromatography. Absorbance and enzyme activity were determined at 280nm and 340nm respectively. There appeared to be one main absorbance peak for the protein at fraction 31, as well as a maximum peak for enzyme activity. SDS-PAGE was conducted in order to estimate the purity and molecular weight of the purified protein. Results showed that the final protein extract had been purified more than the initial crude extract. However, it was difficult to read the bands of the standard lane in the gel. As a result, it was not possible to determine the molecular weight of the protein bands in the sample