Lysozyme and α-lactalbumin have undoubtedly evolved from a common ancestor because of the similarity of their amino acid sequences (1). Studies of α-lactalbumin and lysozyme published before 1990 have been reviewed by McKenzie and White (2). α-Lactalbumin, which is a major milk component of milk whey, is a calcium-binding metalloprotein (3). It is the so-called B component of lactose synthase (4) and acts as a specificity modifier of galactosyltransferase to convert it to lactose synthase (5). The original discovery of its calcium-binding property was made when an effect of ethylenediaminetetracetic acid (EDTA) on the conformational stability of bovine α-lactalbumin was demonstrated. With the addition of 1 mM EDTA, the unfolding temperature decreased by 20-32 degrees. α-Lactalbumin was confirmed by flame spectrophotometry to bind one calcium ion tightly (3). The binding constant for calcium ions to α-lactalbumin has been determined with a variety of methods and the results have been summarized by Kronman (6).