Transfer of sup 67 Cu from ceruloplasmin to superoxide dismutase in K562 cells: Effect of hemin and ascorbate

Journal Article · Thu Feb 09 04:00:00 EST 1989 · FASEB Journal (Federation of American Societies for Experimental Biology); (USA)

OSTI ID:6829501

Percival, S S; Landrum, C P; Harris, E D ^[1]

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1. Texas A M Univ., College Station (USA)

Human erythroleukemic cells (K562) show enhanced binding of ceruloplasmin and transport more copper internally when induced to differentiate with hemin (20 {mu}M). Hemin makes these leukemic cells synthesize fetal and embryonic hemoglobins. We asked if induction causes a greater need for copper possibly as an antioxidant or to synthesize copper-dependent enzymes. To learn more, we compared {sup 67}Cu transport from Cp into Cu, Zn superoxide dismutase (CuZnSOD) in non-induced (NI) vs 48 h hemin-treated cells. {sup 67}Cu-Cp was prepared by an ascorbate-catalyzed exchange reaction. {sup 67}Cu-labeled SOD was confirmed by G-75 chromatography and identification by molecular weight and enzyme activity. The results showed that 10{sup 7} K562 cells incorporated about 2% of the {sup 67}Cu from Cp (0.1 {mu}M) over 1 hr. Hemin treatment raised the uptake by 30%. Both cell types transferred Cp copper to immunoprecipitable CuZnSOD. In NI cells, about 1.0 pmol of {sup 67}Cu (60% of the label in the cytosol) precipitated with antibodies to SOD Hemin-treated cells, precipitated the same absolute amount (1.1 pmol of {sup 67}Cu) but in so doing accounted for only 45% of the total cytosolic {sup 67}Cu. Ascorbic acid enhanced uptake in both cells, but, rather unexpectedly, decreased the amount binding to CuZnSOD. NI cells took up 30% more copper with than without ascorbate, but only 0.64 pmol {sup 67}Cu was precipitable with anti-SOD antibodies. We conclude that inducing K562 cells to differentiate with hemin causes more {sup 67}Cu from Cp to be absorbed into the cytosol, but proportionately less is channeled into CuZnSOD. Ascorbate at physiological levels intensifies binding inhibition. Non-induced cells appear more susceptible to the ascorbate-induced redistribution of copper.

• OSTI ID: 6829501
• Journal Information: FASEB Journal (Federation of American Societies for Experimental Biology); (USA), Journal Name: FASEB Journal (Federation of American Societies for Experimental Biology); (USA) Vol. 3:3; ISSN FAJOE; ISSN 0892-6638
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
ANIMALS
ASCORBIC ACID
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
CARBOXYLIC ACIDS
CERULOPLASMIN
COMPLEXES
COPPER
COPPER 67
COPPER COMPLEXES
COPPER ISOTOPES
DAYS LIVING RADIOISOTOPES
ELEMENTS
ENZYMES
GLOBULINS
GLOBULINS-ALPHA
HEME
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LABELLED COMPOUNDS
MAMMALS
MAN
METALLOPROTEINS
METALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDOREDUCTASES
PIGMENTS
PORPHYRINS
PRIMATES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
SUPEROXIDE DISMUTASE
TRACER TECHNIQUES
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENTS
VERTEBRATES
VITAMINS