ISOLATION AND CHARACTERIZATION OF OCTOPUS HEPATOPANCREATIC GLUTATHIONE-S-TRANSFERASE - COMPARISON OF DIGESTIVE GLAND ENZYME WITH LENS S-CRYSTALLIN

Glutathione S-transferase from Octopus vulgaris hepatopancreas was pur ified to apparent homogeneity by single glutathione-Sepharose-4B affin ity chromatography with overall yield 46% and purification 249-fold. T he enzyme was a homodimer with subunit M(r)24,000, which was smaller t han that of the octopus lens S-crystallin (M(r) 27,000) with glutathio ne-S-transferase-like structure. Both proteins showed substrate specif icities similar to alpha/pi-type isozyme of glutathione S-transferase. Under native conditions, both proteins exhibited multiple forms upon polyacrylamide gel electrophoresis or isoelectric focusing, albeit wit h distinct mobilities; however, only one kind of N-terminal amino acid sequence was determined for the multiple forms of each protein. The h epatopancreatic GST, with pI value 6.6-7.3, dissociated into two monom ers in an acidic or alkaline environment. Two amino acid residues, wit h pK(a) values 5.69 +/- 0.14 and 9.03 +/- 0.11 were involved in the su bunit interactions of the hepatopancreatic enzyme.