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Subcellular Location of NADPH-Dependent Hydroxypyruvate Reductase Activity in Leaf Protoplasts of Pisum sativum L. and Its Role in Photorespiratory Metabolism.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Kleczkowski, Leszek A. Givan, Curtis V. Hodgson, Jonathan M. Randall, Douglas D. |
| Copyright Year | 1988 |
| Abstract | Protoplasts purified from pea (Pisum sativum L.) leaves were lysed and fractionated to assess the subcellular distribution of NADPH-dependent hydroxypyruvate reductase (NADPH-HPR) activity. Rate-zonal centrifugation and sucrose-gradient experiments demonstrated that most (about 70%) of the NADPH-HPR activity was located in the supernatant or cytosol fraction. Detectable, but relatively minor activities were associated with the chloroplast fraction (up to 10% on a chlorophyll basis when compared to the lysate) and with peroxisomes. The minor NADPH-HPR activity in the peroxisomes could be fully accounted for by the secondary NADPH-dependent activity of NADH-dependent HPR. The subcellular distribution of NADPH-HPR followed closely that previously determined for NADPH-dependent glyoxylate reductase (NADPH-GR), an enzyme localized predominantly in the cytosol of pea leaf protoplasts (CV Givan et al. 1988 J Plant Physiol 132: 593-599). Low activities of both NADPH-HPR and NADPH-GR were also found in purified chloroplasts prepared by mechanical homogenization of Pisum and Spinacia leaves. In pea and spinach chloroplasts, rates of both NADPH-HPR and NADPH-GR were lower than the activity of the NADH-dependent GR. The results are discussed in relation to a possible role for NADPH-HPR in the oxidative carbon pathway of photorespiration. Both NADPH-HPR and the GRs could function as auxiliary reactions to photorespiration, utilizing hydroxypyruvate and/or glyoxylate ;leaked' or otherwise exported from peroxisomes. NADPH-HPR function might be especially significant under conditions of limiting NADH supply to peroxisomes, with extraperoxisomal reduced pyridine nucleotide acting as the reductant. |
| Starting Page | 19 |
| Ending Page | 30 |
| Page Count | 12 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.plantphysiol.org/content/plantphysiol/88/4/1182.full.pdf |
| PubMed reference number | 16666441v1 |
| Volume Number | 88 |
| Issue Number | 4 |
| Journal | Plant physiology |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Centrifugation Centrifugation, Zonal Chlorophyll Chloroplasts Cytoplasmic matrix Glyoxylates Gradient Hydroxypyruvate reductase Lysate Lysis NADH NADPH Dehydrogenase Nucleotides Peas - dietary Pisum sativum (pea) extract Plant Leaves Protoplasts Pyridines Spinach - dietary Spinacia Sucrose Supernatant haptoglobin-related protein peroxisome photorespiration pyridine nucleotide |
| Content Type | Text |
| Resource Type | Article |
