Sensitive fluorometric assay for leghemoglobin

Abstract A sensitive spectrofluorometric assay for leghemoglobin is based upon the action of hot saturated oxalic acid on heme proteins. The assay will detect 200 ng of leghemoglobin per milliliter and is specific enough to permit estimation in single nodules or extracts of whole roots. The leghemoglobin concentration measured fluorometrically shows a correlation with nitrogenase [C 2 H 2 ] activity, even during nodule senescence, when standard colorimetric assays may overestimate leghemoglobin.