Department of Biology, McMaster University, Hamilton, Ontario, Canada L8S 4K1.
Plant Physiol. 1977 Nov;60(5):680-3. doi: 10.1104/pp.60.5.680.
The level of asparagine synthetase is low in 10-mm root tips from corn seedings (Zea mays W64 x W182F) but relatively high in mature root sections taken 20 to 35 mm from the tip. When root tips are excised there is a marked increase in asparagine synthetase over a 5-hour period. In mature root sections, on the other hand, the asparagine synthetase activity declines over the same 5-hour period. The increase in the root tip is sensitive to cordycepin, 6-methylpurine, and cycloheximide, which indicates that both RNA and protein synthesis are involved in the formation of asparagine synthetase in the root tip sections. The glutamine analogue azaserine also inhibits formation of the enzyme in root tips, as does glucose. The increase in the root tip is not sensitive to asparagine. Additions of glucose or asparagine have no effect on enzyme activity in extracts. When cycloheximide, azaserine, or glucose is added to the mature root sections there is no effect on recovered enzyme activity.
玉米种子（Zea mays W64 x W182F）10mm 根尖端的天冬酰胺合成酶水平较低，但距尖端 20 至 35mm 的成熟根段相对较高。切除根尖端后，天冬酰胺合成酶在 5 小时内显著增加。另一方面，在成熟的根段中，天冬酰胺合成酶活性在同一 5 小时内下降。根尖的增加对虫草素、6-甲基嘌呤和环己酰亚胺敏感，这表明 RNA 和蛋白质合成都参与了根尖中天冬酰胺合成酶的形成。谷氨酰胺类似物氨甲蝶呤也抑制根尖端酶的形成，葡萄糖也是如此。根尖的增加对天冬酰胺不敏感。添加葡萄糖或天冬酰胺对提取物中的酶活性没有影响。当向成熟的根段中添加环己酰亚胺、氨甲蝶呤或葡萄糖时，对回收的酶活性没有影响。
