School of Biological Sciences, University of East Anglia, NR4 7TJ, Norwich, U.K..
Planta. 1979 Jan;146(2):229-36. doi: 10.1007/BF00388237.
Lemna minor fronds transferred to a sterile culture medium containing 50% (v/v) deuterium oxide ((2)H2O) rapidly undergo a loss of soluble protein with a corresponding increase in free amino acids. The loss of protein is due to two factors: (i) the inhibition of protein synthesis for 4 h followed by a slower rate of synthesis than normal, (ii) a rapid 9-10 fold increase in protein degradation. In plants grown for longer periods (3-6 days) in 50% (2)H2O medium, protein synthesis is inhibited by 20% and the rate constant of degradation is 2-3 times that measured in fronds growing in normal (H2O containing) complete medium. The initial loss of protein is not due to the breakdown of any specific protein fraction. Investigation of several enzymes indicates that all proteins are catabolised in response to (2)H2O treatment. The implications of these results with regard to the interpretation of density-labelling experiments are discussed.
微小浮萍的叶片转移到含有 50%（v/v）重水（(2)H2O）的无菌培养基中后，可溶性蛋白迅速丧失，游离氨基酸相应增加。蛋白质的损失归因于两个因素：（i）在随后的合成速率比正常情况下缓慢的情况下，蛋白质合成被抑制 4 小时；（ii）蛋白质降解的快速增加 9-10 倍。在 50%（2）H2O 培养基中生长更长时间（3-6 天）的植物中，蛋白质合成受到 20%的抑制，并且降解的速率常数是在正常（含有 H2O）完全培养基中生长的叶片的 2-3 倍。初始蛋白质损失不是由于任何特定蛋白质分数的分解。对几种酶的研究表明，所有蛋白质在（2）H2O 处理下都被分解代谢。讨论了这些结果对密度标记实验解释的影响。
