| Abstract: | Alpha‐galactosidase was characterized in two peanuts market types, Runner and Spanish. The enzyme was purified 54 fold using ammonium sulfate precipitation, anion exchange chromatography and Size Exclusion High‐performance Liquid Chromatography. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis indicated that the enzyme has a molecular weight of 30, 000 Da, and isoelectric focusing showed a pI of 5.2. The optimum temperature and pH were 50C and 6.0, respectively. The enzyme had a Km of 0.221 mM when p‐nitrophenyl α‐D‐galactopyranoside (PNPG) was used as a substrate and 80.8 mM when raffmose was a substrate. Raffmose and galactose were found to be competitive inhibitors when PNPG was the substrate: Ki values were 25.4 and 189, respectively. The enzyme was very sensitive to Hg++, Ag++ and to a lesser extent to Cu++. However, ethylcne diamine tetraacetic acid did not have an effect indicating no requirement for cations. The two peanut types tested showed identical enzyme activities. |
