Calcium Insensitivity and Other Properties of αs1 -I Casein

asl-I Casein is the large peptide derived from asl-casein by splitting off the N-terminal peptide (residues 1 to 23) by the action of chymosin, a sl-I casein has been in a variety of cheeses and is thought to have a relationship to cheese texture. Properties of asl-I and asl-caseinswere compared. No marked differences were found in conformation between asl -I and asl-caseins when analyzed by ultracentrifugation and circular dichroism. Calciumbinding capacities were similar, but asl-I casein lacked calcium sensitivity characteristic of asl-casein. It is suggested that the hydrophobic N-terminal region of asl-casein plays an important role in its precipitation by calcium z +.