Assembly of dimeric myeloperoxidase during posttranslational maturation in human leukemic HL-60 cells

Journal Article · Tue Feb 13 00:00:00 EST 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00458a026· OSTI ID:6948892

Taylor, K L; Guzman, G S; Burgess, C A; Kinkade, Jr, J M ^[1]

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1. Emory Univ. School of Medicine, Atlanta, GA (USA)

Myeloperoxidase is a major protein component of the azurophilic granules (specialized lysosomes) of normal human neutrophils and serves as part of a potent bactericidal system in the host defense function of these cells. In normal, mature cells, myeloperoxidase occurs exclusively as a dimer of M{sub r} 150,000 while in immature leukemia cells, there are both monomeric (M{sub r} 80,000) as well as dimeric species. To study the assembly of dimeric myeloperoxidase, azurophilic granules were isolated from either unlabeled or pulse-labeled (({sup 35}S)methionine/cysteine) HL-60 cells, and myeloperoxidase was extracted and separated into monomeric and dimeric forms by FPLC gel filtration chromatography. Steady-state levels of dimeric and monomeric myeloperoxidase were found to account for 67% and 33%, respectively, of the total peroxidase activity and were correlated with the levels of associated heme as measured by absorption at 430 nm. Labeled myeloperoxidase polypeptides were immunoprecipitated using a monospecific rabbit antibody and were identified and quantitated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis/fluorography and liquid scintillation counting. Quantitation of the time course of the conversion of monomeric to dimeric myeloperoxidase indicated a precursor-product relationship at the level of the mature M{sub r} 60,000 subunit. The assembly of dimeric enzyme is a relatively late event in maturation with a t{sub 1/2} of 36 h, implying that this process occurs in more mature, dense azurophilic granules.

• OSTI ID: 6948892
• Journal Information: Biochemistry; (USA), Vol. 29:6; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
PEROXIDASES
POST-TRANSLATION MODIFICATION
ANTIBODIES
CYSTEINE
ELECTROPHORESIS
LYSOSOMES
METHIONINE
MOLECULAR STRUCTURE
NEUTROPHILS
SCINTILLATION COUNTING
SULFUR 35
TUMOR CELLS
AMINO ACIDS
ANIMAL CELLS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
COUNTING TECHNIQUES
DAYS LIVING RADIOISOTOPES
DRUGS
ENZYMES
EVEN-ODD NUCLEI
ISOTOPES
LEUKOCYTES
LIGHT NUCLEI
LIPOTROPIC FACTORS
MATERIALS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANOIDS
OXIDOREDUCTASES
RADIOISOTOPES
SULFUR ISOTOPES
THIOLS
550201* - Biochemistry- Tracer Techniques