Chemical Modification of β-Galactosidase from Macrophomina phaseoli with N-Bromosuccinimide

概要

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Reaction of β-galactosidase from Macrophomina phaseoli with N-bromosuccinimide(NBS)resulted in loss of enzyme activity. The relationship between activity loss and the number of modified tryptophan residues, as well as amino acid analysis, demonstrated that only 1 of the 24 tryptophan residues in the enzyme had been modified. No change in conformation could be detected by optical rotatory dispersion or by sodium dodecyl sulfate gel electrophoresis. Enzyme activity of NBS-modified β-galactosidase towards lactose was different from that towards ο-nitrophenyl-β-D-galactoside(ONPG). The inactivation of lactase activity by NBS modification was almost completely prevented by the presence of excess lactose, but ONPG exerted no influence upon the inactivation of ONPGase activity.From the evidence presented here we can conclude that the one tryprtophan residue which is first accessible to NBS modidication is closely related to lactase activity of Macrophomina β-galactosidase.
社団法人日本生物工学会の論文
1980-02-25