Paik C H, Ebbert M A, Murphy P R, Lassman C R, Reba R C, Eckelman W C, Pak K Y, Powe J, Steplewski Z, Koprowski H
J Nucl Med. 1983 Dec;24(12):1158-63.
Diethylenetriaminepentaacetic acid (DTPA) was conjugated with a practical concentration (300 micrograms/ml) of antibody to human albumin (Ab) and 1083 17-1A monoclonal colorectal antibody (MAb-17-1A) via an acylation reaction using cyclic DTPA anhydride (cDTPAA). The conjugation reaction was favored as pH increased. Bicarbonate buffer at pH 8.2 was chosen for studies of the effect of the cDTPAA-to-antibody ratio on DTPA conjugation with antibody because of its good buffer capacity at that pH. The reaction of cDTPAA with Ab at molar ratios of 2000, 1000, 500, and 100 in the bicarbonate buffer gave rise to 11, 9, 8, and 2 indium atoms incorporated per Ab with 47%, 55%, 59%, and 77% retention of the binding activity. For the conjugation reaction of MAb-17-1A, 29, 28, 31, 11, 4, and 1 indium atoms were incorporated, with the retention of less than 5%, less than 5%, less than 5%, 12%, 60%, and 93% of binding activity when the molar ratio was 5000, 2000, 1000, 500, 100, and 50.
二乙烯三胺五乙酸（DTPA）通过使用环状二乙烯三胺五乙酸酐（cDTPAA）的酰化反应，与实际浓度为300微克/毫升的抗人白蛋白抗体（Ab）和1083 17-1A单克隆结肠直肠癌抗体（MAb-17-1A）进行偶联。随着pH值升高，偶联反应更易发生。由于pH 8.2的碳酸氢盐缓冲液在该pH下具有良好的缓冲能力，因此选择其来研究cDTPAA与抗体的比例对DTPA与抗体偶联的影响。在碳酸氢盐缓冲液中，cDTPAA与Ab的摩尔比为2000、1000、500和100时发生反应，每个Ab结合的铟原子数分别为11、9、8和2，结合活性保留率分别为47%、55%、59%和77%。对于MAb-17-1A的偶联反应，当摩尔比为5000、2000、1000、500、100和50时，结合的铟原子数分别为29、28、31、11、4和1，结合活性保留率分别小于5%、小于5%、小于5%、12%、60%和93%。
