Institute of Agricultural Chemistry, University of Padua, Italy.
Plant Physiol. 1972 Feb;49(2):114-6. doi: 10.1104/pp.49.2.114.
Active transport of SO(4) (2-) and SeO(4) (2-) has been evaluated during 60-hour contact of barley roots with nutrient solutions containing either (35)SO(4) (2-) or (75)SeO(4) (2-), or both ions, at 0.1 milli-equivalent per liter. In the SO(4) (2-) solution the time course of active transport follows a straight line; if SeO(4) (2-) is also present transport is strongly inhibited after 20 to 30 hours for both ions. The S-Se uptake ratio remains 1.4 during the 60 hours; S-Se ratio shifts from 3.0 to 3.3 in proteins and falls to 0.6 in free amino acids. S-Se discrimination is mainly operating at the level of amino acid incorporation into proteins. The presence of Se-amino acids blocks this incorporation and brings about an accumulation of free amino acids; at the same time carrier activity is inhibited. The addition of methionine or Se-methionine causes a 60 to 80% inhibition of the active transport.
在含有 0.1 毫当量/升的（35）SO4（2-）或（75）SeO4（2-）或这两种离子的营养溶液中，用大麦根接触 60 小时期间，评估了 SO4（2-）和 SeO4（2-）的主动运输。在 SO4（2-）溶液中，主动运输的时间过程遵循一条直线；如果同时存在 SeO4（2-），两种离子的运输在 20 至 30 小时后受到强烈抑制。在 60 小时内，S-Se 摄取比保持在 1.4；S-Se 比在蛋白质中从 3.0 到 3.3 变化，并在游离氨基酸中降至 0.6。S-Se 歧视主要在将氨基酸掺入蛋白质的水平上起作用。硒氨基酸的存在阻止了这种掺入，并导致游离氨基酸的积累；同时载体活性受到抑制。添加蛋氨酸或硒蛋氨酸会导致主动运输的 60%至 80%抑制。
