- 作者： 曾義雄; 翁淑芬
- 作者服務機構： 國立中興大學植物學系
- 中文摘要：
Xanthomonas campestris pv. oryzae 之蔗糖分解?存在於其細胞質內。此?受蔗糖刺激誘生達基底含量之4 至10
倍，但不受葡萄糖之降解壓制，亦不受環狀腺?之刺激而增加合成。其比活性隨細胞生長階段而異：在對數期間，隨生長
而升高，但至進入靜止期則開始下降。本研究曾將此?予以部份純化達208倍。對7.0，最適溫度為29°C；二者均窄狹，過此
範圍即顯著減低活性。此?以蔗糖為作用基質時，其Km約為5.3mM。經Sephadex G-200分子篩測估，得其分子量約為
152,000。本文並描述此?之熱穩定性及一些非專一性調節劑對其之影響。本研究中之酵素製備液是否夾雜α-glucosidase，
其可能性並未完全排除。
比 - 英文摘要： Invertase activity is shown to be present in the cytoplasm of Xanthomonas campestris pv. oryzae.It is induced to synthesize by sucrose to about 4 to 10 fold above the basal levels, and the specific activityincreases during the log phase, then declines at the onset of the stationary phase. The enzyme does notappear to be catabolically repressed by glucose nor stimulated to synthesize by 1.25mM adenosine-3', 5'-cyclic monophosphate. This enzyme has been partially purified and shown to hydrolyze surose, turanose, raffinose, melezitose and maltose with relative activities of 100%, 77%, 44% 22% and 12%, respectively.The glucose analogue α-methyl-D-glucoside and fructose act as potent inhibitors; the former was particular-ly shown to be a competitive one. The enzyme has a pH optimum at 7.0 and exhibits maximal activityat 29°C; beyond these values activity decreases rapidly. The Km for sucrose was calculated as approximate-1y 5.3 mM under standard assay conditions. A molecular weight of approximately 152,000 was estimatedfor the enzyme. Stability under heat and effects of some non-specific modulators are also described.The possibility of contaminantion of an α-glucosidase in the enzyme preparation is not completely exclud-ed out.
- 中文關鍵字： --
- 英文關鍵字： --
