Occurrence and Subcellular Distribution of Enzymes Involved in the Glycolate Pathway and Their Physiological Function in a Bleached Mutant of<i>Euglena gracilis</i>z

Yokota, Akiho; Kitaoka, Shôzaburô

doi:10.1080/00021369.1981.10864471

Cited by 1 publication

(2 citation statements)

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“…In these experiments, we used a bleached mutant of Euglena, obtained by removing chloroplasts from the wild-type cells with streptomycin (Buetow, 1968;Mego, 1968) to remove interference by broken chloroplasts with accurate subfractionation of mitochondria. The mutant gives cell functions quite similar to those of the wild-type cells in the enzymic constitution of the glycollate pathway (Kitaoka et al, 1985;Yokota & Kitaoka, 1981). Glyoxylate reductase (NADP+) and glycollate dehydrogenase are localized in mitochondria to constitute the functional glycollate-glyoxylate cycle, as in the wild-type cells (Yokota & Kitaoka, 1981).…”

Section: Resultsmentioning

confidence: 94%

“…The mutant gives cell functions quite similar to those of the wild-type cells in the enzymic constitution of the glycollate pathway (Kitaoka et al, 1985;Yokota & Kitaoka, 1981). Glyoxylate reductase (NADP+) and glycollate dehydrogenase are localized in mitochondria to constitute the functional glycollate-glyoxylate cycle, as in the wild-type cells (Yokota & Kitaoka, 1981). Rotenone-insensitive NADPH-cytochrome c reductase, adenylate kinase, lactate dehydrogenase (cytochrome) and malate dehydrogenase (NAD+) were used as marker enzymes for outer membrane, intermembrane space, inner membrane and matrix respectively (Isegawa et al, 1984).…”

Section: Resultsmentioning

confidence: 94%

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Purification and some properties of glyoxylate reductase (NADP+) and its functional location in mitochondria in Euglena gracilis z

Yokota¹,

Haga²,

Kitaoka³

1985

Biochemical Journal

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Euglena mitochondria contain both glyoxylate reductase (NADP+) and glycollate dehydrogenase to constitute the glycollate-glyoxylate cycle [Yokota & Kitaoka (1979) Biochem. J. 184, 189-192]. Euglena glyoxylate reductase (NADP+) was purified and its submitochondrial location was determined in order to elucidate the cycle. The purified glyoxylate reductase was homogeneous on polyacrylamide-gel electrophoresis. Difference spectra of the purified enzyme revealed that the enzyme was a flavin enzyme. The Mr of the enzyme was 82 000. The enzyme was specific for NADPH, with an apparent Km of 3.9 microM, and for glyoxylate, with an apparent Km of 45 microM. It was 30% as active with oxaloacetate as with glyoxylate. NADH and hydroxypyruvate did not support the activity at all. The optimum pH was 6.45. Submitochondrial fractionation of purified mitochondria showed that the enzyme was located in the intermembrane space and loosely bound to the outer surface of the inner membrane. These properties and the submitochondrial localization of NADPH-glyoxylate reductase facilitate the operation of the glycollate-glyoxylate cycle in combination with glycollate dehydrogenase, which is tightly bound to the inner membrane of Euglena mitochondria.

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Section: Resultsmentioning

confidence: 94%