【摘要】 花生油中亚油酸(LA,C18:2Δ9,12)含量很高,为了研究花生Δ12脂肪酸脱氢酶(Δ12 FAD)的功能,用RT-PCR方法从花生未成熟种子中扩增出AhFAD2B的cDNA,连接到酵母表达载体p416中,并转化酿酒酵母K601,得到工程菌Kp4AFAD2B。气相色谱分析脂肪酸成分,结果表明该基因能在酵母K601中表达,并使菌株产生了两种新的脂肪酸即棕榈二烯酸(C16∶2Δ9,12)和亚油酸(C18∶2Δ9,12),含量分别占总脂肪酸的2.1%和9.2%,棕榈油酸(C16∶1Δ9)和油酸(C18∶1Δ9)含量与对照相比相应地下降,证明该基因编码的Δ12脂肪酸脱氢酶除能作用于C18∶1Δ9,还具有催化16碳的C16∶1Δ9底物在Δ12位脱氢生成C16∶2Δ9,12的功能,但在两种底物之间可能更偏爱C18∶1Δ9。更多还原

【Abstract】 The seed oil of peanut（Arachis hypogaea L.） contains a high level of Linoleic acid(LA,C18∶2^Δ9,12).To study the function of peanut Δ12 fatty acid desaturase（Δ12 FAD）,the cDNA of AhFAD2B was amplified by RT-PCR from immature peanut seeds,then cloned into the shuttle expression vector p416 to generate the recombinant vector p4AFAD2B.The resulting vector was transformed into yeast（Saccharomyces cerevisiae） K601 through LiAc method.The intracellular fatty acid compositions of the engineering strain Kp416 and Kp4AFAD2B were analyzed by gas chromatography（GC）.As a result,the gene can be expressed in k601,two novel peaks in strain Kp4AFAD2B were detected,which were not detectable in the control strain K601.Comparison of the retention times of the newly yielded peaks with those of authentic standards indicated that the fatty acids are hexadecadienoic acid(C16∶2^Δ9,12) and C18∶2^Δ9,12.The contents of C16∶2^Δ9,12 and C18∶2^Δ9,12 correspondingly reached to 2.1% and 9.2% of the total fatty acids respectively in Kp4AFAD2B strain,in the meanwhile,by contrast with control the contents of palmitoleic acid(C16∶1^Δ9) and oleic acid(C18∶1^Δ9) correspondingly decreased by contrast.It is suggested that the Δ12 FAD encoded by AhFAD2B can not only catalyze C18∶1^Δ9 substrate into C18∶2^Δ9,12,but also catalyze C16∶1^Δ9 into C16∶2^Δ9,12 throuth taking off hydrogen atoms at Δ12 site,And it prefer C18∶1^Δ9 much more to C16∶1^Δ9.更多还原