Purification and characterization of small molecular weight myeloperoxidase from human promyelocytic leukemia HL-60 cells

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Abstract
Human myeloperoxidase was purified to homogeneity from human promyelocytic leukemia HL-60 cells. A small MW myeloperoxidase was found in these cells and was separated from 3 other forms of myeloperoxidase of large MW by carboxymethyl-Sepharose CL-6B column chromatography and Sephacryl S-200 gel filtration. The s20,w values of the MW of the small and large myeloperoxidases were 5.2 and 8.07 S, respectively, by sucrose density gradient centrifugation. From these s20,w values, the MW of the small and large myeloperoxidases were estimated to be 79,000 and 153,000, respectively. On electrophoresis in sodium dodecyl sulfate-polyacrylamide gel, the small and large myeloperoxidases each gave 2 bands of protein corresponding to MW of 59,300 and 10,150. The small myeloperoxidase could not be distinguished from the large enzymes by the Ouchterlony double immunodiffusion test but it could be distinguished from them by the microcomplement fixation text. One of the 3 large MW myeloperoxidase was eluted at a lower concentration of methyl .alpha.-D-mannoside than the other 2 on concanavalin A-Sepharose chromatography. The heterogeneity of the myeloperoxidases with large MW may be partly due to differences in their sugar moieties.