Purification and characterization of glucose-6-phosphate dehydrogenase from Cryptococcus neoformans: identification as "nothing dehydrogenase".
Purification and characterization of glucose-6-phosphate dehydrogenase from Cryptococcus neoformans: identification as "nothing dehydrogenase".
复制标题
新型隐球菌中葡萄糖-6-磷酸脱氢酶的纯化和表征：鉴定为“无脱氢酶”。
DOI：
10.1006/abbi.1994.1392
复制
发表时间：
1994
影响因子：
3.9
通讯作者：
Mallett,TC
中科院分区：
文献类型：
--
作者：
Niehaus,WG;Mallett,TC
Glucose-6-phosphate dehydrogenase (EC 1.1.1.49) was purified fromCryptococcus neoformans, a basidiomyceteous yeast that is an opportunistic pathogen of AIDS patients. The enzyme had a subunit molecular weight of 5 × 104, a specific activity of 50 units mg−1, andKmvalues for NADP and glucose-6-phosphate of 1.6 and 24 μM, respectively. The enzyme catalyzed the dehydrogenation of glucose, in the presence of dimethylsulfoxide, withKmof 5 mM andVmax10% of that with glucose-6-phosphate. pH profiles indicated the presence of a group with pKaof 6.6 that is involved in catalysis, and groups with pKas of about 8.8 that are involved in binding of NADP and glucose-6-phosphate. The enzyme was inhibited by NADPH, competitive versus NADP, withKiof 1 μM, and by zinc ion, competitive versus glucose-6-phosphate, withKiof 2 μM. Crude enzyme extract catalyzed an appreciable rate of reduction of NADP in the absence of added substrate, a "nothing dehydrogenase" activity. This activity was shown to be due to the presence of glucose-6-phosphate in the crude extract. It was calculated that cells ofC. neoformanscontain about 25 μmol of glucose-6-phosphate per gram, wet weight.
