n-acetyl-beta-hexosaminidase activity in human breast milk.
1. The lysosomal enzyme, N-acetyl-beta-hexosaminidase (HEX) is present in human breast milk. It is composed predominantly of "A" (heat-labile) and "B" (heat-stable) isozymes which coelute with the corresponding major serum isozymes on DE-52 ion-exchange chromatography. 2. Total HEX activity in "early" milk obtained at 2.8 +/- 1.4 weeks post partum, is approx. 2.5-fold higher (87 +/- 29 nmol/60'/mg protein. n = 10) than that of pregnancy serum (35.7 nmol/60'/mg protein) prior to delivery. 3. These levels increase to greater than 3-fold (110 +/- 20 nmol/60'/mg protein, n = 13) as the milk matures (10.3 +/- 4.2 weeks). 4. The specific activity of HEX A in the milk changes little with time post partum, because absolute 5. In contrast, HEX B specific activity is increased, as absolute levels (per volume) remain constant in the face of decreasing milk protein content, 5. These changes result in a high degree of correlation (r = 0.81) between time of lactation and % HEX A observed.
D000293:Adolescent; D000328:Adult; D005260:Female; D054818:Hexosaminidase A; D054819:Hexosaminidase B; D006596:Hexosaminidases / Q000097:blood / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007774:Lactation; D008894:Milk Proteins / Q000378:metabolism; D008895:Milk, Human / Q000201:enzymology*; D049590:Postpartum Period; D011247:Pregnancy; D013997:Time Factors; D001619:beta-N-Acetylhexosaminidases
D007527:Isoenzymes; D008894:Milk Proteins; D006596:Hexosaminidases; D054818:Hexosaminidase A; D054819:Hexosaminidase B; D001619:beta-N-Acetylhexosaminidases