Assay of protein-quinone coupling involving compounds structurally related to the active principle of poison ivy
✍ Scribed by Joseph S. Byck; Charles R. Dawson
- Publisher
- Elsevier Science
- Year
- 1968
- Tongue
- English
- Weight
- 823 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0003-2697
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✦ Synopsis
Although it has been shown (1) that urushiol, the allergenically active oil produced by the poison ivy plant, is a mixture of 3-pentadecylcatechol and three similar catechols having varying degrees of olefinic unsaturation in the side chain, present chemical knowledge of urushiol's physiological mode of activity is limited. As the result of studies on humans by Keil, Wasserman, and Dawson (2), by Kligman (3), and by Baer and co-workers (4), it has been demonstrated that both the vicinal hydroxyl groups and the alkyl side chain play important roles in the activity. The advantages of using 3-pentadecylcatechol as a clinical standard for biological testing instead of the unstable mixture of naturally occurring olefins have also been described. Consequently, it is a matter of considerable interest to explore further the relationship between chemical structure and biological activity of such compounds.
Any immunochemical pathway suggested for the poison ivy allergy must include a step or sequence of steps by which the components of urushiol, acting as haptens, can combine in V~VCJ with a protein (or some other suitable macromolecule) to yield an antigen. A number of ways can be conceived by which conjugation of protein molecules with catecholic haptens might occur. One pathway, however, seemed particularly attractive in that it involved only well-documented reactlons known to take place in biochemical systems. Thus it is proposed that after contact with the host the poison ivy catechols are enzymically oxidized to the corresponding o-benzoquinones. Conjugation with proteins might then be expected to occur in the following way. A well-documented reaction of quinones is the 1,4-dipolar addition of nucleophilic species (5,6). Were this reaction to occur (as indicated in Figure 1) between the haptenquinone and a nucleophilic group on a protein, such as a terminal amino or sulfhydryl group (designated as BH in Figure 1)) the result would be