Hetmann Anna, Kowalczyk Stanisław
Nicolaus Copernicus University, Institute of General and Molecular Biology, Department of Biochemistry, Toruń, Poland.
Acta Biochim Pol. 2009;56(1):143-53. Epub 2009 Mar 4.
Nucleoside diphosphate kinase (NDPK) (EC 2.7.4.6), the enzyme transferring the phosphate residue from ATP to nucleoside diphosphates, is localized mainly in the cytoplasm and mitochondria and in smaller amounts in cell nuclei and the microsomal fraction. Exposure of etiolated oat seedlings to red light causes an increase of the enzyme activity by about 42% in nuclear fraction, 7% in etioplastic and 14% in postetioplastic fraction. Endogenous phytochrome A, as visualized by an immunochemical method, translocates from the cytoplasm into the nucleus upon red, far-red or white light activation. Nuclei purified from oat seedlings contain two, and the postnuclear fraction four easily separated forms of NDPK. One of the nuclear isoforms (I(n)) and one isoform isolated from the postnuclear fraction (II(pn)) are activated by red light in the presence of phytochrome A purified from etiolated oat coleoptiles. Both phytochrome A-activated NDPKs purified to electrophoretic homogeneity have the same molecular mass (17-18 kDa) determined by SDS/PAGE. Both enzymes in the native form have similar molecular masses (71 and 63 kDa).
核苷二磷酸激酶（NDPK）（EC 2.7.4.6），即一种将磷酸残基从ATP转移至核苷二磷酸的酶，主要定位于细胞质和线粒体中，在细胞核和微粒体部分中的含量较少。将黄化燕麦幼苗暴露于红光下，会使该酶活性在细胞核部分增加约42%，在黄化质体部分增加7%，在黄化质体后部分增加14%。通过免疫化学方法可视化的内源性光敏色素A，在红光、远红光或白光激活后，会从细胞质转运至细胞核。从燕麦幼苗中纯化得到的细胞核含有两种，而核后部分含有四种易于分离的NDPK形式。一种核异构体（I(n)）和一种从核后部分分离得到的异构体（II(pn)）在从黄化燕麦胚芽鞘中纯化得到的光敏色素A存在的情况下会被红光激活。通过SDS/PAGE测定，纯化至电泳均一性的两种光敏色素A激活的NDPK具有相同的分子量（17 - 18 kDa）。两种天然形式的酶具有相似的分子量（71和63 kDa）。
