Malate Dehydrogenase Isozymes in Plants: Preparation, Properties, and Biological Significance

Ting, Irwin P.; Führ, Irene; Curry, Russell A.; Zschoche, William C.

doi:10.1016/b978-0-12-472702-1.50028-1

Cited by 22 publications

(22 citation statements)

References 48 publications

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“…Gradient fractions were assayed for ATPase (pH 6.5 and 9), NADH-malic dehydrogenase, latent IDPase, and NADH-Cyt c reductase. Malic dehydrogenase is a sensitive marker for mitochondria in corn roots (24). Latent IDPase and NADH-Cyt c reductase are believed to be markers for Golgi apparatus membranes and ER, respectively (19).…”

Section: Methodsmentioning

confidence: 99%

Plasma Membrane-associated Adenosine Triphosphatase Activity of Isolated Cortex and Stele from Corn Roots

Leonard

Hotchkiss²

1978

Plant Physiol.

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The psma membrane fractions from separated cortex and stele of prumy roots of corn (Zea mays L. WF9 x M14) contained cation ATPase activity at similar levels but with somewhat different properties. ATPase activity from cortex was optimum at pH 6.5, showed a simple Michaelis-Menten saturation with increasing ATP Mg, and showed complex kinetic data for K+ stimlation dmiar in character to the kinetic data for K+-ATPase and K+ influx in primy roots. The results for cortex indicate that homogenates of pri_may roots are dominated by membranes from cortical cells.ATPae activity from stele was optimum at pH 6.5 and showed another mxmum at pH 9. At pH 6.5, activity from stele had properties simiar to that from cortex except that the kinetics of K+ stimolation dosely approached that expected for a Michaelis-Menten enzyme. At pH 9, the enzyme actvity from stele was inhibited by 5 g/ml oligomycin, sggesting that a s nt portion of the activity was of mitochondrial origin. Sucrose density gradient analysis indicated some contamination of mitochondrial membranes in the plsma membrane fraction from stele. The results for stele are consistent with the view that stelar parenchyma cells are not deficient in ion pumps.

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Section: Methodsmentioning

confidence: 99%

Plasma Membrane-associated Adenosine Triphosphatase Activity of Isolated Cortex and Stele from Corn Roots

Leonard

Hotchkiss²

1978

Plant Physiol.

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“…Multiple alleles at each locus have been reported. Gene products from the same subcellular compartment form interlocus and intralocus heterodimers, but no heterodimers are formed between cytosolic and mitochondrial subunits (4,5 (3,5)]. Thus these double-nulls lack cytosolic MDH activity and do not represent merely electrophoretically unstable isozymes.…”

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confidence: 99%

“…The mitochondrial isozymes of NAD-specific malate dehydrogenase (MDH; L-malate:NAD' oxidoreductase, EC 1.1.1.37) are associated with the tricarboxylic acid cycle and, in conjunction with the cytosolic MDH isozymes, may also participate in a proposed "malate-aspartate shuttle" for transferring reducing equivalents between the cytoplasm and mitochondria (1)(2)(3). Genetic studies have shown that the mitochondrial MDH isozymes in sporophytic tissues of maize are encoded by three independently inherited nuclear loci (Mdhl, Mdh2, and Mdh3) located on chromosomes 8, 6, and 3, respectively (4,5); the cytosolic MDHs are encoded by two loci (Mdh4 and Mdh5) located on chromosomes 1 and 5, respectively (4)(5)(6).…”

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confidence: 99%

Malate dehydrogenase: viability of cytosolic nulls and lethality of mitochondrial nulls in maize.

Goodman¹,

Newton²,

Stuber³

1981

Proc. Natl. Acad. Sci. U.S.A.

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Five independently inherited loci on five distinct chromosomes encode the mitochondrial and cytosolic isozymes of NAD-dependent malate dehydrogenase (MDH; L-malate:NAD' oxidoreductase, EC 1. 1. 1.37). Multiple alleles, including electrophoretic nulls, occur for each locus. However, a single allele of normal activity at one of the three loci encoding the mitochondrial MDHs is sufficient for normal development, whereas plants with essentially no cytosolic MDH activity function normally. The requirement of a normal activity allele at one of the three structural loci encoding the mitochondrial MDHs demonstrates in plants that a commonly studied dehydrogenase enzyme is essential for normal embryogenesis.Coleoptile sheaths from 5-day-old seedlings were used for routine electrophoretic analyses, following published procedures (4). Scutellar samples were obtained from mature kernels that had been soaked overnight; they were analyzed by published procedures (5). Immature kernel extracts were homogenized in a sucrose/sodium ascorbate buffer (4) after removal of the pericarp; they were subjected to the same conditions of electrophoresis and staining as were the coleoptilar extracts.Mitochondrial MDH antiserum was prepared against purified MDH2 homodimer from the H25 line (7).The mitochondrial isozymes of NAD-specific malate dehydrogenase (MDH; L-malate:NAD' oxidoreductase, EC 1.1.1.37) are associated with the tricarboxylic acid cycle and, in conjunction with the cytosolic MDH isozymes, may also participate in a proposed "malate-aspartate shuttle" for transferring reducing equivalents between the cytoplasm and mitochondria (1-3). Genetic studies have shown that the mitochondrial MDH isozymes in sporophytic tissues of maize are encoded by three independently inherited nuclear loci (Mdhl, Mdh2, and Mdh3) located on chromosomes 8, 6, and 3, respectively (4, 5); the cytosolic MDHs are encoded by two loci (Mdh4 and Mdh5) located on chromosomes 1 and 5, respectively (4)(5)(6). Multiple alleles at each locus have been reported. Gene products from the same subcellular compartment form interlocus and intralocus heterodimers, but no heterodimers are formed between cytosolic and mitochondrial subunits (4, 5). Electrophoretic null or near-null alleles, which fail to produce either electrophoretically detectable homo-or heterodimers, exist at each locus. Here we report our attempts to produce plants lacking cytosolic and mitochondrial MDH activities in order to test whether or not either function is essential for plant growth and development. MATERIALS AND METHODSNull alleles for Mdhl, Mdh2 and Mdh5 were obtained from inbred lines Ky2l, H25, and Tx325, respectively (4). Null alleles for Mdh3 and Mdh4 were extracted from Latin American collections (Gua 159 and Bov 1032, respectively). By intercrossing stocks homozygous for nulls at different loci and by selecting appropriately among the various F2 progeny, we developed four distinct stocks, each of which was simultaneously homozygousnull at two loci: (i) Mdhl, Mdh2; (ii) Mdhl, M...

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“…Ting et al (12) have previously postulated that MDH isozymes are specific to particular organelles, which in higher plants, serve to regulate by compartmentation, separate biochemical pathways, containing common enzymic reactions. This is in contrast with procaryotes, where isozymes control the separate pathways by their different characteristics such as differential feedback inhibition.…”

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confidence: 99%

“…For example, microbody MDH in the glyoxysomes functions in the glyoxylate cycle, and in the peroxisomes, according to Tolbert's scheme of photorespiration, functions in supplying NAD or NADH for the reversible reaction between hydroxypyruvate and glycerate (13). The latter MDH reaction is considered to operate by means of a shuttle with the cytoplasmic form(s) of MDH (12).…”

mentioning

confidence: 99%

Microbody Malate Dehydrogenase Isozyme in Cotyledons of Cucumis sativus L. during Development

Wainwright¹,

Ting²

1976

Plant Physiol.

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The properties of the microbody malate debydrogenase (EC 1.1.1.37) (MDH) isozyme from cotyledons of Cucumus sativus L. were compared during development. It is conduded that the isozyme remains unaltered, despite the transition from glyoxysomal to peroxisomal function that occurs during greening of the cotyledons. This condusion is based on electrophoretic behavior, chromatographic elution from DEAE-cellulose, molecular weight, kinetic behavior, and immunological identity. In most cases, the distinct properties of the other MDH isozymes in the tissue during development provide additional support for an unchanging microbody isozyme. A method for assaying specifically the microbody isozyme was developed; a diluted preparation was assayed spectrophotometrically before and after complete immunological precipitation. The turnover of the microbody MDH isozyme was investigated by a radioactive labeling study. There is incorporation into both glyoxysomal and peroxisomal MDH. Degradation rates do not correspond with either decline of glyoxysomal activity or the continuation of peroxisomal activity. Apparently, the microbody MDH isozyme is continually turned over throughout cotyledon development.The transition, during the development of epigeal cotyledons, from a primary function of fat metabolism (nongreen cotyledons) to one of photosynthesis (green cotyledons) has been correlated with a parallel transition in microbody function. In particular, the development of microbodies in cucumber cotyledons has been well documented by electron microscopy (14).This work has substantiated earlier findings on sunflower cotyledons (4, 10) that the microbodies are first associated with the lipid bodies (for lipid catabolism), whereas later they are associated with chloroplasts and contain peroxisomal enzymes (functioning in photorespiration) (13). A previous study on catalase indicated that during the transition, the three-band isozyme pattern on electrophoresis is supplemented by an additional nine bands (3). By contrast, evidence is presented here that the microbody MDH isozyme is not altered during the transition in microbody function. The isozyme is organelle-specific rather than being adapted to the particular metabolic pathway in which it is involved. In addition, radioactive labeling experiments have given some insight into the turnover (synthesis and degradation) of the isozyme during glyoxysomal and peroxisomal function. This work is more fully detailed in a thesis dissertation (15). MATERIALS AND METHODSPlant Material and Preparation of the Homogenates. Seeds of a Burpee hybrid and the Straight Eight variety (6033-5) of cucumber (Cucumis sativus L.) were grown in vermiculite in a dark chamber (30 C) for the first 4 days and then transferred to a growth chamber with a 12-hr light/dark regime, with corresponding temperatures of 26.5 C and 15.5 C, respectively.The washed cotyledons were homogenized in 2 volumes of cold grinding medium (0.1 M tris or K phosphate at pH 7.5, containing 1 mM EDTA and 1 mm DTF) at 4 C, either ...

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Malate Dehydrogenase Isozymes in Plants: Preparation, Properties, and Biological Significance

Cited by 22 publications

References 48 publications

Plasma Membrane-associated Adenosine Triphosphatase Activity of Isolated Cortex and Stele from Corn Roots

Plasma Membrane-associated Adenosine Triphosphatase Activity of Isolated Cortex and Stele from Corn Roots

Malate dehydrogenase: viability of cytosolic nulls and lethality of mitochondrial nulls in maize.

Microbody Malate Dehydrogenase Isozyme in Cotyledons of Cucumis sativus L. during Development

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