INCIDENCE OF MOLECULAR-FORMS OF BILE SALT-STIMULATED LIPASE IN PRETERM AND TERM HUMAN-MILK

Preterm and term human milk samples obtained at various times after de livery were analyzed for the presence of molecular forms of the human milk enzyme, bile salt-stimulated lipase (BSSL). Thirty-five percent o f both the preterm and term milk samples contained two molecular forms of BSSL, of variable molecular mass. The remainder contained only one molecular species of either 115 kD (50%) or 120 kD (15%). The number of molecular forms present was not related to length of lactation, mat ernal age, gestation, or maternal blood group. The specific activity o f BSSL purified from term milk was similar to that purified from prete rm milk, and there was no difference in specific activity whether one or two molecular forms were present. This study demonstrates heterogen eity of both molecular mass and molecular forms. We conclude that pret erm babies fed their own mother's milk are unlikely to be disadvantage d with respect to fat digestion as BSSL secreted in preterm milk appea rs to be very similar to that produced in term milk, although we canno t exclude other functional differences.