Mn2+ transport across biological membranes may be monitored spectroscopically using the Ca2+ indicator dye antipyrylazo III.
The metallochromic indicator antipyrylazo III can be used for the rapid and convenient monitoring of Mn2+ transport in biological systems. The apparent KD of the Mn-antipyrylazo III complex in buffered 150 mM KCl (pH 7.2 at 20 degrees C) is approximately 2.5 x 10(-5) M. The sensitivity of antipyrylazo III to Mn2+ is comparable to that of arsenazo III to Ca2+. Mn2+ can be measured without interference from Ca2+, by using dual-wavelength spectrophotometry at the wavelength pair 510-590 nm, or 530-565 nm in cell or mitochondrial suspensions. Ca2+ can be monitored at the wavelength pair 720-790 nm without interference from Mn2+. This paper represents the first application of this technique, here used to characterize mitochondrial efflux kinetics of Mn2+. We report that Mn2+ is transported out of liver mitochondria with a Vmax of 1-2 nmol/(mg.min) and a Km of about 12 nmol/mg. These results are in close agreement with results of measurements using 54Mn.
Gavin
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University of Rochester Medical Center, New York 14642.
Gunter
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Gunter
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D000818:Animals; D001667:Binding, Competitive; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D004396:Coloring Agents; D007202:Indicators and Reagents; D007700:Kinetics; D008345:Manganese / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D009282:Naphthalenesulfonates; D011189:Potassium Chloride / Q000494:pharmacology; D013053:Spectrophotometry
D004396:Coloring Agents; D007202:Indicators and Reagents; D009282:Naphthalenesulfonates; D008345:Manganese; D011189:Potassium Chloride; C016238:antipyrylazo III; D002118:Calcium