Mechanism of maturational decline of rat intestinal lactase-phlorizin hydrolase.
Mechanism of maturational decline of rat intestinal lactase-phlorizin hydrolase.
复制标题
大鼠肠道乳糖酶-根皮苷水解酶成熟衰退的机制。
DOI：
10.1042/bj2820107
复制
发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Castillo,RO
中科院分区：
文献类型：
--
作者：
Tsuboi,KK;Kwong,LK;Sunshine,P;Castillo,RO
研究了乳龄至断奶后早期各组幼鼠乳糖酶-芽孢素水解酶（LPH）活性的成熟下降。蔗糖酶-异麦芽糖酶（SI）和麦芽糖酶-葡萄糖淀粉酶（MG）活性的相关成熟增加也被检查作为比较。在这段时间内，观察到三种酶的细胞浓度变化，反映了酶活性的相应变化。利用标记亮氨酸作为标记物，研究了伴随这些浓度成熟变化的合成模式。LPH的合成被发现维持在恒定的速率，与成熟相关的浓度下降无关，而SI和MG细胞浓度的增加是由于酶的加速合成。基于预标记LPH池中标记亮氨酸的分数合成率和消失率，LPH的周转率在定量上与LPH浓度的下降相似。这些发现与我们之前的建议一致，即LPH的成熟下降是由于加速更新而发生的，而不是其合成速度的降低。
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.