Abstract
The analytical potential of the reaction of ammonia with o-phthalaldehyde mercaptoethanol reagent at pH 7 (an atypical fluorescence) has already been demonstrated. This, coupled with additional findings reported here, has led to an ammonia determination well suited to nitrogenase studies. As a result, large numbers of samples can be rapidly analyzed by high-pressure liquid chromatrography methods under mild conditions and without prior microdiffusion. Neither sodium dithionite (or other components of the usual nitrogenase assay), nor alternative substrates (cyanide, azide, methyl isonitrile), nor their products (methylamine, dimethylamine, hydrazine) interfere. High-pressure liquid chromatography showed that the fluorescent “product” of the o-phthalaldehyde mercaptoethanol reagent-ammonia reaction was, in fact, more than just a single compound. Despite this, once the proper solvent composition was found, high-pressure liquid chromatography with a small inexpensive C18 “guard” column proved quite fast and reproducible for this measurement. Fluorescence response to ammonia was linear to at least 40 nmol/ml. A previous problem, long-term stability of the fluorescence, was solved by running the reactions in the dark. Background ammonia in the buffer could be substantially reduced by an analogous o-phthalaldehyde mercaptoethanol reagent reaction, using t-butyl mercaptan, and solvent extraction.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Burgess B. K., Jacobs D. B., Stiefel E. I. Large-scale purification of high activity Azotobacter vinelandII nitrogenase. Biochim Biophys Acta. 1980 Jul 10;614(1):196–209. doi: 10.1016/0005-2744(80)90180-1. [DOI] [PubMed] [Google Scholar]
- Li J., Burgess B. K., Corbin J. L. Nitrogenase reactivity: cyanide as substrate and inhibitor. Biochemistry. 1982 Aug 31;21(18):4393–4402. doi: 10.1021/bi00261a031. [DOI] [PubMed] [Google Scholar]
- Roman R. J., Bonventre J. V., Lechene C. P. Fluorometric assay for urea in urine, plasma, and tubular fluid. Anal Biochem. 1979 Sep 15;98(1):136–141. doi: 10.1016/0003-2697(79)90717-6. [DOI] [PubMed] [Google Scholar]
- Rubinson J. F., Corbin J. L., Burgess B. K. Nitrogenase reactivity: methyl isocyanide as substrate and inhibitor. Biochemistry. 1983 Dec 20;22(26):6260–6268. doi: 10.1021/bi00295a034. [DOI] [PubMed] [Google Scholar]
- Simons S. S., Jr, Johnson D. F. Reaction of o-phthalaldehyde and thiols with primary amines: fluorescence properties of 1-alkyl(and aryl)thio-2-alkylisoindoles. Anal Biochem. 1978 Oct 15;90(2):705–725. doi: 10.1016/0003-2697(78)90163-x. [DOI] [PubMed] [Google Scholar]
- Taylor S., Ninjoor V., Dowd D. M., Tappel A. L. Cathepsin B2 measurement by sensitive fluorometric ammonia analysis. Anal Biochem. 1974 Jul;60(1):153–162. doi: 10.1016/0003-2697(74)90140-7. [DOI] [PubMed] [Google Scholar]