Purification and partial characterization of antifreeze proteins from leaves of Ligustrum lucidum Ait

Three AFPs (AFP-1, AFP-2, AFP-3) of Ligustrum lucidum Ait leaves were purified by using ice-affinity, chromatography separation on a DEAE-cellulose-32 column and a Sephadex G100 column. The ice-affinity proteins were about 1.2 mg/100 g leaves. Their molecular weight was 66.1, 26.3, and 20.2 kDa, respectively. Their thermal hysteresis activity was 0.379, 0.678, and 0.460 °C respectively. Asx was very abundant in these AFPs; its molar ratio was 22.2, 24.9, and 27.8%, respectively. AFP-2 was effective to protect peroxidase, β-glucosidase, and trehalose synthase from freeze–thawing process. Cryoprotection of AFP-2 is better than trehalose.