【作者】 杨焕文； 吕芬；

【Author】 YANG Huan-wen LV Fen(College of Tobacco Science of Yunnan Agricultural University,Kunming 650201,China)

【机构】 云南农业大学烟草学院；

【摘要】 两年的试验结果表明,深色晾烟采收晾制后,体内硝酸还原酶活性剧烈下降。晾制后3～5d,叶肉和主脉体内硝酸还原酶活性即下降至0。晾制3周内体外硝酸还原酶活性极低,几乎接近0。晾制3周后逐渐增加, 两年试验分别在晾制后5～6周达到最高峰,这可能与微生物有关。两种电子供体之间,使用 methyl viologen 的活性大于使用 NADH 的,但之间无显著差异。晾制过程中体外硝酸还原酶活性变化规律与亚硝酸和烟草特有亚硝胺变化的规律一致,只是变化时间比后二者提前一周,这个结果表明烟草特有亚硝胺的前体物质亚硝酸盐主要来自体外硝酸还原酶还原的亚硝酸盐。更多还原

【Abstract】 A two years study indicated that nitrate reductase activity(NRA)in vivo sharply decreased after harvest.and was zero after three to five days fir-curing both in lamina and midrib.NRA in vitro was very low,and was near zero in 3 weeks during air-curing both in lamina and midrib and increased after 3 weeks air-curing and reached maximum after 5 weeks to 6 weeks air-curing in midrib.This observation suggests the presence of microbes on the leaf surface contributing to NRA.Two electron donors was not significant,methyl viologen was slighter higher than with NADH.Changes of NRA in vitro was the same nitrite and tobacco-specific nitrosamines(TSNA),and changes of NRA was faster than that of nitrite and TSNA.This results showed that nitrite,the precursor was from NRA in vitro.更多还原