Purification and Chemical Modification of Yeast Invertase

Abstract:

In this study,yeast invertase(β-fructofuranoside hydrolase) was extracted and purified by cell disruption,heat denaturation,organic solvent precipitation and DEAE-Sepharose Fast Flow chromatography.Five chemical modification agents(PMSF,DTT,SUAN,NBS,EDTA) and several other metal ions were used to determine the amino acid residues involved in the active site of yeast invertase.The result indicated that serine residues and metal ions were inessential to the invertase activity while the lysine and cysteine residues were linked to the enzyme activity, which were not in the active site of the enzyme.That the indolyl ring of tryptophan residues could be modified by N-bromosuccinimide and these groups could be protected by sucrose revealed that the tryptophan residues were present at the invertase active site.