Lernmark U., Gardestrom P.
Department of Plant Physiology, University of Umea, S-901 87 Umea, Sweden.
Plant Physiol. 1994 Dec;106(4):1633-1638. doi: 10.1104/pp.106.4.1633.
Protoplasts from barley (Hordeum vulgare), pea (Pisum sativum), wheat (Triticum aestivum), and spinach (Spinacia oleracea) leaves were fractionated into chloroplast- and mitochondrion-enriched fractions. Pyruvate dehydrogenase complex capacities in mitochondria (mtPDC) and chloroplasts (cpPDC) were measured in appropriate fractions under conditions optimal for each isozyme. The total cellular capacity of PDC was similar in barley and pea but about 50% lower in wheat and spinach. In pea a distribution of 87% mtPDC and 13% cpPDC was found on a cellular basis. In barley, wheat, and spinach the subcellular distribution was the opposite, with about 15% mtPDC and 85% cpPDC. cpPDC activity was constant at about 0.1 nmol cell-1 h-1 in cells from different regions along the developing barley leaf and showed no correlation with developmental patterns of photosynthetic parameters, such as increasing Chl and NADP-glyceraldehyde-3-phosphate dehydrogenase activity. Similarly, the capacity of the mitochondrial isoform did not change during barley leaf development and had a developmental pattern similar to that of citrate synthase and fumarase. Differences in subcellular distribution of PDCs in barley and pea are proposed to be due to differences in regulation, not to changes in isozyme proportions during leaf development or to species-specific differences in phosphorylation state of mtPDC after organelle separation.
将大麦（Hordeum vulgare）、豌豆（Pisum sativum）、小麦（Triticum aestivum）和菠菜（Spinacia oleracea）叶片的原生质体分离成富含叶绿体和线粒体的组分。在每种同工酶的最佳条件下，于合适的组分中测定线粒体（mtPDC）和叶绿体（cpPDC）中的丙酮酸脱氢酶复合体活性。大麦和豌豆中PDC的总细胞活性相似，但小麦和菠菜中的约低50%。在豌豆中，基于细胞水平发现mtPDC占87%，cpPDC占13%。在大麦、小麦和菠菜中，亚细胞分布情况相反，mtPDC约占15%，cpPDC约占85%。在发育中的大麦叶片不同区域的细胞中，cpPDC活性恒定在约0.1 nmol·细胞⁻¹·小时⁻¹，且与光合参数的发育模式无相关性，如叶绿素增加和NADP - 甘油醛 - 3 - 磷酸脱氢酶活性增加。同样，线粒体同工型的活性在大麦叶片发育过程中没有变化，其发育模式与柠檬酸合酶和延胡索酸酶相似。大麦和豌豆中PDC亚细胞分布的差异被认为是由于调节差异，而非叶片发育过程中同工酶比例的变化或细胞器分离后mtPDC磷酸化状态的物种特异性差异。
