A simplified method for the synthesis of a radioiodinated DNP-hapten

Abstract

The synthesis of the DNP-hapten, α-N-(4-hydroxyphenacetyl)-ϵ-N-(2,4-dinitrophenyl)- l-lysine (HDL) was initially described by Meyer-Delius, et al. (1971). HDL can be easily iodinated by the method of Hunter and Greenwood (1962) and has been particularly useful for the detection of anti-DNP antibodies. 125I or 131I (HDL) have been employed by Meyer-Delius et al. (1971), Montgomery and Williamson (1970, 1972) and Montgomery et al. (1972) to measure the binding properties of anti-DNP antibodies in a salt precipitation test (Farr, 1958; Stupp et al., 1969). Radioiodinated HDL has proven most useful for the visualization of anti-DNP antibodies in analytical isoelectric focusing. Isoelectric focusing in thin layers of polyacrylamide gel was shown by Awdeh et al. (1968) to resolve a specifically purified antibody population into a pattern of discrete bands or an antibody isoelectric spectrum. The usefulness of this method has been greatly extended by employing radioiodinated HDL to directly visualize the anti-DNP antibody isoelectric spectrum without the need for antibody purification (Montgomery and Williamson, 1970, 1972; Montgomery et al., 1972; Williamson, 1971). The procedures for the synthesis of HDL described by Meyer-Delius et al. (1971) are quite laborious and difficult to reproduce. In order to make this useful hapten available to other laboratories we have developed a simplified synthetic procedure for HDL which is reported in the present communication.