Correction for creatine interference with the direct indophenol measurement of NH3 in steady-state nitrogenase assays
Dilworth, M.J., Eldridge, M.E. and Eady, R.R. (1992) Correction for creatine interference with the direct indophenol measurement of NH3 in steady-state nitrogenase assays. Analytical Biochemistry, 207 (1). pp. 6-10.
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Creatine was identified as a major source of interference with the direct phenol/hypochlorite colorimetric determination of ammonia in nitrogenase reaction mixtures. A method is described for removing other compounds which inhibit color development and for compensating for the interference produced by creatine. This method avoids time-consuming microdiffusion and also routinely makes available the efficiency of ATP hydrolysis coupled to substrate reduction (View the MathML source ratio) with N2 as a reducible substrate. Using this method we determined values for this ratio at 30°C of 4.87 ± 0.03 during the reduction of protons to H2 and 7.16 ± 0.14 during the reduction of N2 by the vanadium-containing nitrogenase of Azotobacter chroococcum.
|Publication Type:||Journal Article|
|Murdoch Affiliation:||School of Biological and Environmental Sciences|
|Copyright:||© 1992 Published by Elsevier Inc.|
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