The maturational decline in lactase-phlorizin hydrolase (LPH) activity was studied in groups of young rats ranging from suckling to early post-weaned states. Associated maturational increases in sucrase-isomaltase (SI) and maltase-glucoamylase (MG) activities were also examined as a comparison. Over this time period changes in cellular concentrations of the three enzymes were observed, reflecting corresponding changes in enzyme activities. Synthesis patterns accompanying these maturational changes in concentration were examined using labelled leucine as a marker. Synthesis of LPH was found to be maintained at constant rates independent of the maturation-associated decline in its concentration, whereas the increases in cellular concentrations of SI and MG were due to accelerated synthesis of the enzyme. Turnover of LPH, based on both the fractional synthesis rate and the disappearance rate of labelled leucine from prelabelled LPH pools, was increased in a quantitatively similar way to the decline in LPH concentration. These findings are consistent with our earlier proposal that the maturational decline of LPH occurs because of accelerated turnover, without a decrease in its rate of synthesis.
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Research Article|
February 15 1992
Mechanism of maturational decline of rat intestinal lactase-phlorizin hydrolase
K K Tsuboi;
K K Tsuboi
1Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305-5119, U.S.A.
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L K Kwong;
L K Kwong
1Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305-5119, U.S.A.
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P Sunshine;
P Sunshine
1Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305-5119, U.S.A.
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R O Castillo
R O Castillo
1Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305-5119, U.S.A.
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Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1992 The Biochemical Society, London
1992
Biochem J (1992) 282 (1): 107–113.
Citation
K K Tsuboi, L K Kwong, P Sunshine, R O Castillo; Mechanism of maturational decline of rat intestinal lactase-phlorizin hydrolase. Biochem J 15 February 1992; 282 (1): 107–113. doi: https://doi.org/10.1042/bj2820107
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