Tissue fractionation studies. 6. Intracellular distribution patterns of enzymes in rat-liver tissue

Abstract

I955 more acidic solutions, with pH < 7 0, a few seconds elapsed before equilibrium was attained. Taking into account the ionization of the haem-linked group on MetMb and the higher oxidation state, the variation of Kb,. with pH is shown to confirm the conclusion that 2 moles of H+ are liberated/mole of acidic MetMb. Using 6-1 for the pK of the group in MetMb as established in other studies, the results give a pK of 75 for the group in the higher oxidation state at 200 and I = 0 04. 3. The variation of KRb, with temperature gives AHO = 10-0 ± 2*0 kcal./g.mol.: if the ionization of the haem-linked group is allowed for, the value 9*0 ± 1.0 kcal./g.mol. is obtained. 4. The dependence of Kob. on ionic strength is in accord with a change in charge from + 1 on MetMb to zero on the higher oxidation state. 5. The results are shown to favour the ferryl ion structure, or an isomer of this structure, for the higher oxidation state. The isomeric structures would, in general, require the presence of another ionizing group in myoglobin, but no evidence for such an ionization could be found. With other direct evidence favouring the ferryl ion structure this is to be preferred, and the higher oxidation state may provisionally be named ferrylmyoglobin. We gratefully acknowledge grants from the Department of Scientific and Industrial Research, and the Medical Research Council, held by one of us (D.H.I.) during the course of this investigation.

Tissue distribution and subcellular localization of phosphatidylcholine transfer protein in rats as determined by radioimmunoassay

“…2 shows the subcellular distribution, expressed as relative specific. activity versus percent protein, as suggested by De Duve et al [32]. The supernatant fraction has the highest specific activity and contains 60% of the total PC-transfer protein, but considerable amounts are present in the other fractions as well.…”

Platinum complexes inhibit ATP‐driven basic dye uptake in lysosomes from rat liver

“…In other trials, highly purified lysosomes were obtained by centrifuging the F II fraction (practically identical to the L fraction in [18], and prepared as before except that EDTA was absent in the sucrose medium) in a discontinuous metrizamide gradient, according to [19]; only the L2 subfraction described in the above paper was used in these studies. Enrichment in specific activity of acid phosphatase over the homogenate in the best preparations was -60-70-fold; these values are very similar to those reported.…”

“Free” Enzymic Activity of Mitochondrial Fractions from Liver Tumours

“…enzyme-containing particles present in mitochondrial fractions but distinct from mitochondria (Duve, Pressman, Gianetto, Wattiaux and Appelmans, 1955). If, however, these particles from rats fed azo-dye were already damaged at the time of the mitochondrial centrifugation, acid phosphatase would have become soluble (cf.…”