Abstract
Lactase specific activity(SA) rises immediately after birth in the rat, reaches a peak at 9-12 d of age and declines to adult levels shortly after weaning. These studies were intended to determine the relationship of mature(L) to precursor(ProL) forms of lactase in suckling, weanling and adult Sprague-Dawley rats. Homogenized jejunal mucosa was used for measurement of enzyme SA (μmol/min/g protein) and for immunoisolation and purification of L and ProL. The relative quantities of each polypeptide were determined by densitometry. Samples were also treated with Endo H and Endo F. Enzyme SA and distribution are shown below.
All bands were sensitive to Endo F treatment, none to Endo H. These studies demonstrate that: 1)the decrease in lactase SA in adult rats is associated with an increase in the level of a 200 kDa protein, 2) these changes occur at weaning when lactase SA is decreasing and may be partially responsible for lower SA seen in older animals. We speculate that these age-related changes may result from an alteration in a post-translational event.
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Dudley, M., Reeds, P., Shulman, R. et al. POST-TRANSLATIONAL MODIFICATION OF LACTASE-PHLORIZIN HYDROLASE DURING DEVELOPMENT. Pediatr Res 27, 539 (1990). https://doi.org/10.1203/00006450-199005000-00085
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DOI: https://doi.org/10.1203/00006450-199005000-00085