STUDIES ON PROTEIN SYNTHESIS AND AMINO ACID COMPARTMENTATION

放射性标记体内蛋白质合成速率的测定 前兆是有问题的，因为关于相对的 蛋白质分解衍生的未标记氨基酸对蛋白质的贡献 蛋白质合成的前体库。量化的 放射自显影测定脑局部比率的方法 体内蛋白质合成(LCPS)与羧基标记的脂肪族， 作为示踪剂的支链氨基酸考虑了 示踪氨基酸的未标记物种。脑蛋白质的比率 研究表明，大鼠再生神经的合成增加 出生后脑内大部分脑区的核团和数量减少 随着年龄的增长和衰老。可卡因治疗改变了LCPs 选择性大脑区域；变化的方向取决于 治疗史。对猴子正常睡眠的研究表明 慢波睡眠与许多大脑中LCPs的增加有关 地区。在越冬地松鼠中，LCPS是深刻的和 在整个大脑中可逆地减少。浅硫喷妥钠麻醉 大鼠导致广泛但非常轻微的脑部疾病发生率下降 蛋白质合成。一般而言，LCPs的变化可能会标记大脑区域 对药物、治疗或治疗做出长期调整的 生理状态的改变。 缬氨酸驱油条件下的循环利用及LCPS研究 演示蛋白质合成所需氨基酸的区隔作用。连 当血浆缬氨酸浓度增加100倍时，蛋白质 降解继续提供相当大比例的Valine用于 蛋白质合成和亮氨酸比例增加。

In vivo measurements of rates of protein synthesis with radiolabeled precursors are problematic because of uncertainties about the relative contribution of unlabeled amino acids derived from protein breakdown to the precursor pool for protein synthesis. The quantitative autoradiographic method for the determination of local rates of cerebral protein synthesis (lCPS) in vivo with a carboxyl-labeled, aliphatic, branched-chain amino acid as tracer takes into account recycling of the unlabeled species of the tracer amino acid. Rates of cerebral protein synthesis in rats have been shown to increase in regenerating nerve nuclei and decrease in most brain regions during postnatal brain development and with senescence. Cocaine treatment changes lCPS in selective brain regions; the direction of the changes depends on the history of treatment. Studies of normal sleep in monkeys indicate that slow wave sleep is linked with increased rates of lCPS in many brain regions. In hibernating ground squirrels, lCPS is profoundly and reversibly reduced throughout the brain. Light thiopental anesthesia in rats results in widespread but very small decreases in rates of cerebral protein synthesis. In general, changes in lCPS may mark brain regions undergoing long-term adjustments in response to a drug, a treatment, or a change in physiological state. Studies of recycling and lCPS under valine-flooding conditions demonstrate compartmentation of amino acids for protein synthesis. Even when plasma valine concentrations are increased 100 fold, protein degradation continues to supply a significant portion of valine for protein synthesis and an increased portion of leucine.