碩士 / 國立中興大學 / 植物學系 / 85 / Glutamine synthetase (GS) plays a key role in nitrogen
assimilation in filamentous N2-fixing cyanobacterium Anabaena
CH1. The enzyme was purified by four-step procedure involving
ammonium-sulfate fractionation , diethylaminoethyl (DEAE)-
Sepharose CL-6B chromatography , Sephacryl S-200 chromatography
, and affinity chromatography on Matrex Gel Red A. This
purification scheme resulted in a 35-fold and 19％recovery of
the initial specific and total activities.The native GS had a
approximate molecular mass of 619 kDa as estimated by non-
denaturing PAGE, and interpolation of the Ferguson plots. It was
composed of tweleve identical subunits of molecular mass 53.4
kDa.The pH optimum values were 7.4, 8.2 and 8.2 for the g-
glutamyltransfer, g-glutamylsynthetic and biosynthetic assays.
The temperature optimum of activity were 55, 60 and 60℃for the
g-glutamyltransfer, g-glutamylsynthetic and biosynthetic
activities, respectively. g-glutamyltransfer activity was
inhibited by L-methionine-DL-sulfoximine.Apparent Michaelis
constants (Km) for ATP and glutamate were 0.43 and 9.09 mM in g-
glutamylsynthetic assay, and 4.52 and 20 mM in biosynthetic
assay. That for ADP, glutamine and NH2OH were 0.03, 20.83 and
5.26 mM in g-glutamyltransfer assay, 0.11 mM for NH2OH in g-
glutamylsynthetic assay. The GS of Anabaena CH1 exhibited two Km
values which were 0.8 and 54.64 mM in the presence of ammonium
concentrations lower and higher than 7.5 mM.
| Identifer | oai:union.ndltd.org:TW/085NCHU0366023 |
| Date | January 1997 |
| Creators | Kao, Jia-Yin, 高嘉霠 |
| Contributors | Pei-Chung Chen, 陳伯中 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 78 |
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