Preparation and Properties of Poly-DL-alanyl-lysozyme
1968 年 63 巻 6 号 p. 730-738
詳細
1968 年 63 巻 6 号 p. 730-738
1. Poly-DL-alanyl-lysozyme (PAL) was prepared from lysozyme [EC 3. 2. 1. 17] and N-carboxy-DL-alanine anhydride, and was purified by CM-cellulose column chromatography. The effluent containing PAL was fractionated for further studies.
2. Six samples of PAL were obtained : The enrichment of these samples with alanine was in the range between 31 and 150 residues per molecule. The number of alanyl residues attached to lysozyme increases with increasing ratio of reacting alanine monomer to lysozyme. Although all of the lysyl side chains in the lysozyme molecule are exposed to the solvent, there seems to be a difference in the accessibility among the lysyl residues.
3. No conformational change, caused by the addition of polyalanyl groups, could be detected from the measurement of optical rotatory dispersion and circular dichroism.
4. The enzymatic activity of PAL toward glycol chitin decreases proportionally with the average length of the polyalanyl side chain. The formation of the ES-complex is inhibited by the polyalanyl side chains. These facts suggest that polyalanyl side chains sterically hinder the interaction of the enzyme molecule with substrate.
5. The effect of polyalanyl side chains on the lytic activity is more marked than that on the activity toward glycol chitin, and the lytic activity of PAL remarkably depends on pH. This implies that not only the active center, but also some other sites of the enzyme molecule are involved in the interaction of lysozyme with M. lysodeicticus and that the net charge affects the interaction.
