Abstract
When the phytopathogenic toxin of Pseudomonas tabaci, the causative agent of wildfire disease of tobacco, is hydrolyzed with strong HCl, a ninhydrin-positive substance is produced (1). Because this substance moved on paper chromatograms more slowly than the recognized a-amino acids’ and because of its ready destruction by chloramine-T, the tentative conclusion was reached that hydrolysis of this toxin liberated a previously unknown amino acid. The object of this paper is t,o describe the isolation of this new amino acid in pure form and to tell of the determination of its structure as a, E-diamino-fl-hydroxypimelic acid. Because this amino acid is contained within the toxin of P. tabaci, the short, trivial name tabtoxinine is proposed for it. The structure was established in the following manner. Elementary analyses showed that the isolated substance corresponded to the formula C,H1406N2. Aqueous solutions of it were neutral. Measurement of carbon dioxide evolved showed that practically all the nitrogen was estimable by the decarboxylation procedure with ninhydrin, and this behavior strongly indicated that the nitrogen atoms were present as amino groups situated (Y to carboxyl groups. These facts suggested that the new compound was a hydroxydiaminopimelic acid, and this seemed to correlate well with its migration on paper strips. Work (2) has recently described the isolation of a!, E-diaminopimelic acid from hydrolysates of the diphtheria bacillus, and has shown that it migrates slowly on paper strips developed with phenol.’ The finding t,hat our new compound (which differed in empirical formula from that of Work by only 1 oxygen atom) moved even more slowly (RF 0.10 in phenol saturated with water) was enough t’o suggest that it might be a hydroxydiaminopimelic acid. This proved to be the case. The position of the hydroxyl group was established as being adjacent to one of the amino groups by the use of sodium periodate. This reagent rapidly destroyed the new amino acid and 1 equivalent of periodate was consumed in the process. After this reaction a small amount of a sub-
Highlights
Measurement of carbon dioxide evolved showed that practically all the nitrogen was estimable by the decarboxylation procedure with ninhydrin, and this behavior strongly indicated that the nitrogen atoms were present as amino groups situated
The finding t,hat our new compound moved even more slowly (RF 0.10 in phenol saturated with water) was enough t’o suggest that it might be a hydroxydiaminopimelic acid
The quantitative measurement of carbon dioxide evolved when tabtoxinine was heated with ninhydrin led to the conclusion that all the nitrogen in the molecule was amino nitrogen
Summary
Measurement of carbon dioxide evolved showed that practically all the nitrogen was estimable by the decarboxylation procedure with ninhydrin, and this behavior strongly indicated that the nitrogen atoms were present as amino groups situated These facts suggested that the new compound was a hydroxydiaminopimelic acid, and this seemed to correlate well with its migration on paper strips. The finding t,hat our new compound (which differed in empirical formula from that of Work by only 1 oxygen atom) moved even more slowly (RF 0.10 in phenol saturated with water) was enough t’o suggest that it might be a hydroxydiaminopimelic acid. The resulting suspension was concentrated under reduced pressure to about half of its volume in order to remove ammonia, and the precipitate was filtered off HOOC-i: - CH2- CH2-S-CH3 l4H2 Methionine
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