Characterization of the tetramer-dimer-monomer equilibrium of the enzymically active subunits of pigeon liver malic enzyme

The pH-induced reversible dissociation of pigeon liver malic enzyme (EC 1.1.1.40) was studied by combined use of chemical cross-linking and SDS/polyacrylamide-gel electrophoresis. The tetrameric enzyme showed a pH-dependent dissociation in an acidic environment. At pH values above 8.0 most molecules existed as tetramers. The enzyme was gradually dissociated at lower pH. When the pH was below 5.0 most of the enzyme was present as the monomeric forms. Reassociation of the subunits was accomplished by adjusting the pH to neutrality. The dissociation and reassociation were almost instantaneous. No trimer was detected. The pigeon liver malic enzyme was thus shown to have a double-dimer quaternary structure with D2 symmetry. In the presence of substrates, the monomer-dimer-tetramer equilibrium favours the direction of dissociation. Tartronate, an L-malate analogue, was found to be more effective than L-malate in this process. When the monomeric forms were immobilized, the enzyme subunits were found to be fully active in catalysis. A possible arrangement of the four identical subunits of the enzyme molecule is proposed to account for the results obtained in this investigation. The origin of the half-of-the-sites reactivity of pigeon liver malic enzyme is also discussed.

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Characterization of the NADP malic enzyme gene family in the facultative, single-cell C4 monocot Hydrilla verticillata

Photosynthesis Research ◽

10.1007/s11120-007-9212-y ◽

2007 ◽

Vol 94 (1) ◽

pp. 43-57 ◽

Cited By ~ 17

Author(s):

Gonzalo M. Estavillo ◽

Srinath K. Rao ◽

Julia B. Reiskind ◽

George Bowes

Keyword(s):

Gene Family ◽

Single Cell ◽

Malic Enzyme ◽

Hydrilla Verticillata ◽

Enzyme Gene ◽

Malic Enzyme Gene

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Cloning and characterization of a NADP+-malic enzyme gene fromBradyrhizobium japonicumUSDA110

Soil Science & Plant Nutrition ◽

10.1080/00380768.2002.10409261 ◽

2002 ◽

Vol 48 (5) ◽

pp. 711-717 ◽

Cited By ~ 2

Author(s):

Suphawat Sinsuwongwat ◽

Amane Kodera ◽

Takakazu Kaneko ◽

Satoshi Tabata ◽

Mika Nomura ◽

...

Keyword(s):

Malic Enzyme ◽

Enzyme Gene ◽

Malic Enzyme Gene

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Isolation and characterization of Schizosaccharomyces pombe mutants with defective NAD-dependent malic enzyme

Canadian Journal of Microbiology ◽

10.1139/m86-088 ◽

1986 ◽

Vol 32 (6) ◽

pp. 481-486 ◽

Cited By ~ 13

Author(s):

C. Osothsilp ◽

R. E. Subden

Keyword(s):

Schizosaccharomyces Pombe ◽

Malic Enzyme ◽

Pool Analysis ◽

Starch Gel Electrophoresis ◽

Wild Type ◽

Isolation And Characterization ◽

Starch Gel ◽

Colony Color ◽

Color Indicator

To obtain NAD-dependent malic enzyme mutants of Schizosaccharomyces pombe, a colony color indicator screening system was developed. Mutants defective for malic acid utilization (mau mutants) are yellow, while wild-type colonies are blue on the defined bromcresol green based indicator medium. NAD-dependent malic enzyme mutants were distinguished from other mau mutants by subsequent, starch gel electrophoresis, spectrophotometry, complementation tests, and intermediate pool analysis with cell-free extracts.

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