Chen Jingbo

Isolation,Purification and Trait of Cu,Zn SODs in Tobacco Leaves

Three isoenzymes, Cu, Zn-superoxide dismutases I, Ⅱand III, were isolated from ripe fresh tobacco leaves (K326,Nicotinana) by extraction with 50 mmol/L, pH7.6 phosphate buffer solution (PBS), successive precipitation with 55%-60% (w/w) ammonium sulfate, frozen ethanol-chloroform and acetone, and isolation by DEAE-52 column (balance eluted for 6h with 20mmol/L, pH 7.6 PBS, flow rate 0.25mL/min, then linear gradient-eluted with 20-100mmol/L PBS, flow rate 0.25mL/min) and then by DEAE-52 ion-exchange column (linear gradient-eluted with 30-100 mmol/L PBS, flow rate 0.25mL/min). Pure Cu, Zn-superoxide dismutases I and III were prepared further by G-75 gel column (eluted with 10mmol/L, pH7.6 PBS, flow rate 0.3 mL/min) and freeze-dried at -20℃. It was found that Cu, ZnSODⅠconsisted of 302 amino acid residues, its relative molecular mass was 36682 Da, maximum absorption wavelength was 262 nm, optimal pH value was around 6.0, and optimal temperature was 40℃; Cu, ZnSOD III consisted of 187 amino acid residues, its relative molecular mass was 22976 Da, maximum absorption wavelength was 269 nm, the maximum fluorescence excitation and emission wavelengths were 280 nm and 338 nm, respectively, optimal pH value was 5.0-6.0, and optimal temperature was 30℃.

Relationship Between Aroma Constituents and Smoking Quality of Redried Flue-cured Tobacco, C3F, Grown in Different Areas

The aroma constituents in the redried flue-cured tobacco,C3F,grown in different areas,(including) Sanming of Fujian Province,Lanshan of Hunan Province,Yuzhou and Sanmenxia of Henan Province,Xingyi of Guizhou Province,and Xuanwei,Baoshan and Fuyuan of Yunnan Province,in 2003 were analyzed with simultaneous distillation and extraction(SDE) and GC/MS.Fifty-five compounds were identified,of which twenty-five important aroma constituents were quantified.The sensory evaluation of tobacco samples was conducted by panelists.The results showed that: 1) the total amounts of the 25 important aroma constituents differed to a certain extent between different areas,the growing areas in the order of aroma constituent amounts were: FuyuanBaoshanSanmenxiaXingyiYuzhouLanshanXuanweiSanming,the amount in Fuyuan C3F was higher than that in Sanming C3F by 20%;2) no significant differences were found in the contents of aldehydes and heterocycles,while the contents of(ketones,) alcohols,esters and neophytadiene in the samples were significantly different;3) the smoking quality of tobacco samples agreed with the changes of total amounts of the 25 aroma constituents.