METABOLISM OF CYTOKININ - DERIBOSYLATION OF CYTOKININ RIBONUCLEOSIDE BY ADENOSINE NUCLEOSIDASE FROM WHEAT-GERM CELLS
METABOLISM OF CYTOKININ - DERIBOSYLATION OF CYTOKININ RIBONUCLEOSIDE BY ADENOSINE NUCLEOSIDASE FROM WHEAT-GERM CELLS
复制标题
DOI：
10.1104/pp.68.5.1020
复制
发表时间：
1981-01-01
期刊：
影响因子：
7.4
通讯作者：
KRISTOPEIT, SM
中科院分区：
文献类型：
--
作者：
CHEN, CM;KRISTOPEIT, SM
从小麦胚芽中部分纯化腺苷核苷酶（腺苷核糖水解酶，EC 3.2.2.7），其催化N6-（Δ 2-异戊烯基）腺苷和腺苷的去糖基化以形成相应的碱基。这种酶（MW 59，000 ±. 3000）在4.7的最佳pH下使核糖核苷去糖基化。细胞分裂素核苷和腺苷的Km值在30 ℃下在50 mM Tris-柠檬酸盐缓冲液（pH 4.7）中分别为2.38和1.43 μ M。C.腺苷和其它细胞分裂素核苷的存在抑制N6-（Δ 2-异戊烯基）腺苷的水解，但该反应对鸟苷、尿苷或3 ″-脱氧腺苷不敏感。植物细胞中足够水平的活性细胞分裂素可以通过细胞分裂素核苷的去糖基化与其他细胞分裂素代谢酶协同作用来提供。
Adenosine nucleosidase (adenosine ribohydrolase, EC 3.2.2.7) which catalyzes the deribosylation of N6-(.DELTA.2-isopentenyl)adenosine and adenosine to form the corresponding bases was partially purified from wheat germ. This enzyme (MW 59,000 .+-. 3000) deribosylates the ribonucleosides at an optimum pH of 4.7. Km values for the cytokinin nucleoside and adenosine are 2.38 and 1.43 .mu.M, respectively, in 50 mM Tris-citrate buffer (pH 4.7) at 30.degree. C. The presence of adenosine and other cytokinin nucleosides inhibited the hydrolysis of N6-(.DELTA.2-isopentenyl)adenosine, but this reaction was insensitive to guanosine, uridine or 3''-deoxyadenosine. An adequate level of active cytokinin in plant cells may be provided through the deribosylation of cytokinin riboside in concert with other cytokinin metabolic enzymes.