Abstract
The amino acid compositions of alginate lyases, SP1 and SP2 were slightly different from each other. They contained about five mol of sugar per molecular weight (25, 000). The reaction with DTNB or PDS suggested that the enzymes contained one sulfhydryl group buried in the molecule and two disulfide bonds. It was obvious from the NBS-oxidation of the enzymes and the protection by the substrate of SP1 that one residue out of 11 Trp residues for SP1 and of 9 Trp residues for SP2 was essential for the activity. Treatment with TNBS rendered the enzymes inactive when 7 of 13 Lys residues for SP1 and 4 of 13 Lys residues for SP2 were trinitrophenylated in 20mM phosphate buffer, pH 8.0. However, kinetic analysis showed that one Lys residue in the active unit was possibly involved in enzyme function.
