Expression and degradation patterns of chitinase purified from Xuehuali (Pyrus bretschneiderilia) pollen

The present study investigated the expression pattern of chitinase in Xuehuali (Pyrus bretschneiderilia) pollen, as well as its subsequent degradation. The chitinase was purified and collected using chitin affinity column chromatography with regenerated chitin. After purification, four additional chitinase isozymes (chiA, chiB, chiC, and chiD) and chitinase (Chi II) were clearly expressed on SDS-PAGE gels that contained 0.01% glycol chitin. The chitinase reaction products were examined using GlcNAc, (GlcNAc)2, (GlcNAc)3, (GlcNAc)4, (GlcNAc)5, and (GlcNAc)6 as substrates at 2 and 24 h after reaction via TLC and HPLC. The (GlcNAc)4 oligosaccharide was slightly degraded to (GlcNAc)2 after 24 h of reaction with Xuehuali pollen chitinase on TLC. Meanwhile, (GlcNAc)5 was degraded to (GlcNAc)2-4, and 2300 ppm (GlcNAc)6 was degraded to 246 ppm (GlcNAc)2, 208 ppm (GlcNAc)3, 572 ppm (GlcNAc)4, and 336 ppm (GlcNAc)5 on HPLC. With regard to temperature, the strongest Xuehuali pollen chitinase activity (0.69 unit/mL) was observed at 37 °C after 3 h of incubation, and with regard to pH, the strongest activity (0.72 unit/mL) was observed at pH 3 after 3 h of incubation. The main chitin oligomers degraded from (GlcNAc)6 were (GlcNAc)2 and (GlcNAc)4.