Egg White Lysozyme Purification with Sweet Potato [Ipomoea batatas (L.) Lam] Leaf Preparations

Isolation and purification of lysozyme from egg white was improved by utilization of alcohol-insoluble solids (AIS) and cross-linked AIS (CLAIS) of sweet potato [Ipomoea batatas (L.) Lam] leaves, an agricultural waste. Egg white was homogeneously diluted 3-fold with distilled water. The lysozyme was isolated and purified by three methods. The first was the batch type of AIS, and products with 28-fold purification and 57% yield were obtained; the second was the batch type of CLAIS column elution with 100 mM acetic acid containing 500 mM NaCl, and products with 74-fold purification and a 59% yield were obtained; the third was CLAIS column elution with linear salt gradients of 0-500 mM NaCl in 10 mM carbonate buffer (pH 9.3), and products with 86-fold purification and 58% yield were obtained.