Activity of N-acetyl-β-D-hexosaminidase (HEX) and its isoenzymes A and B in human milk during the first 3 months of breastfeeding
Advances in Medical Sciences
Purpose: Milk contains free and bound oligo-and heteropolisaccharides, which protect newborns against pathogens and have nutritional value. N-acetyl-b-D-hexosaminidase (HEX), the most active lysosomal exoglycosidase, modify and degrade oligo-and heteropolysaccharides. The objective of our study was to determine HEX activity and isoenzymes A and B in the progression of lactation. Material and methods: Human milk samples were collected from 51 women on the 3 rd , 21 st and 100 th day postpartum.
... th day postpartum. Enzymatic activity was determined the Zwierz et al method modified by Marciniak et al. Protein and lactose concentrations were determined by a MilkoScan 4000 apparatus. Results: The total HEX activity decreased by the 21 st day in comparison to the 3 rd day, and increased by the 100 th day as compared to the 21 st day. HEX A activity decreased by the 21 st and the 100 th day as compared to the 3 rd day. HEX B activity decreased by 21 th day and has the tendency to decrease by the 100 th day as compared to the 3 rd day. Protein concentration decreased and the lactose concentration increased in milk taken on the 21 st day in comparison to concentration of protein and lactose on the 3 rd day. HEX and its isoenzymes' activity significantly correlate with the progression of lactation. At the beginning of lactation, HEX A activity, which releases hexosamines from acidic oligosaccharides, dominates; later, HEX B releases hexosamines from neutral oligosaccharides. Conclusions: To better understand the degradation of human milk oligosaccharides, it would be useful to investigate and document their detailed structures and evaluate the activity of other exoglycosidases' activity in human breast milk over the course of lactation.