Duplicate mixtures containing 50 mmol/L Tris HCl, pH 7.5 (23°C), 3 mmol/L dithiothreitol, 5 mmol/L MgCl₂ , and 50 mg/mL of each of 4 dialyzed β-thalassemic hemolysates were prepared with or without 1.0 μmol/L Ubal. The unincubated mixtures were frozen and sent to Dr E. Beutler of the Scripps Research Institute (La Jolla, CA) for measurement of enzyme activities.33 The results, estimated to have a precision of ± a few percent, are reported in international units of activity normalized to the Hb content of the hemolysates (IU/g Hb).

Abbreviations: GAPD, glyceraldehyde phosphate dehydrogenase; PGK, phosphoglycerate kinase; GPI, glucose phosphate isomerase; TPI, triosphosphate isomerase; MetHb Red, methemoglobin reductase.