The purification of aconitase

Abstract

ACTION OF oc-AMYLASES 99 3. Nevertheless, under these conditions, some maltotriose, maltose and glucose are formed by fission of longer chains. The yield of glucose is far below that expected from a random fission. 4. The action of these enzymes on dilute amylopectin yielded, in the early stages, negligible traces of fission products of shorter chain length than 6-8 units. Salivary and fungal (A8pergillu8 oryzae) amylases under the same conditions yielded products of chain length of 3 units and upwards. 5. Dilute amylose in corresponding reactions yielded appreciable quantities of fission products of chain length of 2 units and upwards (malt and salivary) or 3 units and upwards (bacterial and fungal). 6. Salivary amylase does not readily attack the first two, and the bacterial and malt cx-amylases the first five linkages from the non-reducing end. 7. Salivary and malt oc-amylases readily attack the second and bacterial amylase the third linkage from the reducing end, other linkages nearer this end with increasing difficulty. It is concluded that linkages other than those near the ends here specified are attacked at random. 8. The action of the x-amylases on shorter linear chains, such as maltohexaose and maltotriose, is restricted as regards linkages near the non-reducing end so that fission must often take place nearer to the reducing end than is normal, and more glucose may be formed. 9. A hypothesis is suggested to explain the actions of the a-amylases. One of us (R. B.) is indebted to the Department of Scientific and Industrial Research for a grant, for which we express our thanks.

Investigations of the Role of Iron in Chlorophyll Metabolism. II. Effect of Iron Deficiency on Chlorophyll Synthesis

“…The reduced incorporation of citrate and isocitrate into b-AL in iron-deficient blood (17) may be due in part to the requirement of animal aconitase for iron (9,16). Recently DeKock (3) and co-workers reported that iron deficiency greatly reduced the aconitase activity of mustard leaves, but they were unable to demonstrate a direct association of iron with the enzyme.…”

“…2 Contribution from the Botany and Bacteriology Department (14) and in avian blood (5,6,17) lhas been suggested. The reaction mediated by aconitase may limit the rate of b-AL synthesis in iron-deficient tissues of animals (9,16) and plants (3).…”

The Kinetics of the Reactions Catalyzed by Aconitase

“…As the studies on the kinetics of aeonitase had been made with crude or partially purified jireparations of the enzyme, the previous work was repeated with a more highly purified enzyme preparation (Morrison, 1954a). The question of the lag period was investigated, also the relative rates of the reactions catalyzed by aeonitase.…”

Parallel Partial Purification of Cytoplasmic and Mitochondrial Aconitate Hydratases from Rat Liver

“…A partial purification of aconitate hydratase from different sources has been reported [12,14,16]; Villafranca and Mildvan [17] have recently obtained 76-fold purification of the pig heart enzyme, which appeared 95O/, pure. These methods resulted probably in the purification of the cytoplasmic enzyme only, also when total homogenates were used: a t least in the case of rat liver mitochondria, the use of highly hypotonic conditions is not sufficient to allow a notable release of the mitochondrial enzyme, but freezing and thawing or sonication are required (Buffa and Guarriero-Bobyleva, unpublished observation).…”