The nitriles β-[11C]cyano-L-alanine 1 and γ-[11C]cyano-α-amino-L-butyric acid 2 were obtained by enzymatic catalysis from O-acetyl-L-serine and O-acetyl-L-homoserine with carrier added hydrogen [11C]cyanide (0.1 µmol), using O-acetyl-L-serine sulfhydrylase [EC.4.2.99.8] and O-acetyl-L-homoserine sulfhydrylase [EC.4.2.99.10], respectively. L-[4-11C]Aspartate 3 and L-[5-11C]glutamate 4 were then obtained by alkaline hydrolysis of 1 and 2, respectively. Purification by semi-preparative HPLC yielded 3 and 4 with radiochemical purities higher than 95% and with decay corrected radiochemical yields of 60–70% and 50–60%, respectively based on the total amount of collected hydrogen [11C]cyanide. The enantiomeric purities were determined, after derivatisation with N-α-(2,4-dinitrophenyl-5-fluoro-)-L-alaninamide, by HPLC to be higher than 97.5%. The total reaction times for 3 and 4, counted from end of bombardment, were 50–55 min. The specific radioactivity of 3 and 4 were approximately 30 GBq/µmol at end of synthesis starting from 20 GBq hydrogen [11C]cyanide. Copyright © 2001 John Wiley & Sons, Ltd.
以 O-乙酰基-
L-丝氨酸巯基酶[
EC.4.2.99.8]和
O-乙酰基-L-高丝氨酸巯基酶[
EC.4.2.99.10]为载体,添加[11C]
氰化氢(0.1 µmol),通过酶催化从 O-乙酰基-
L-丝氨酸和
O-乙酰基-L-高丝氨酸中分别获得腈 β-[11C]
氰基-
L-丙氨酸 1 和 γ-[11C]
氰基-α-
氨基-L-
丁酸 2。.2.99.8]和
O-乙酰基-L-高丝氨酸巯基酶[
EC.4.2.99.10]。然后分别通过碱
水解 1 和 2 得到 L-[4-11C]
天冬氨酸 3 和 L-[5-11C]谷
氨酸 4。通过半制备高效
液相色谱法纯化得到的 3 和 4 的放射
化学纯度高于 95%,根据收集的[11C]
氰化氢总量计算,衰变校正放射
化学收率分别为 60-70% 和 50-60%。经 HPLC 测定,用 N-α-(2,4-
二硝基苯基-5-
氟)-L-丙
氨酰胺衍生后,对映体纯度高于 97.5%。从轰击结束算起,3 和 4 的总反应时间为 50-55 分钟。从 20 GBq [11C]cyanide 氢开始,合成结束时 3 和 4 的比放射性约为 30 GBq/µmol。Copyright © 2001 John Wiley & Sons, Ltd. All Rights Reserved.