• 作者： 曾義雄; 彭國証
• 作者服務機構： 國立中興大學植物學系
• 中文摘要： 植物病原細菌 Xanthomonas campestris pv. campestris能在以澱粉為唯一碳源之培養基上生長良好，係因在此菌誘
  生胞外 -澱粉　?。麥芽糖誘生的　-澱粉?量比澱粉誘生者更高。經查此菌除　-澱粉?外，另具胞內麥芽糖?。本研究
  由培養液中經超微過瀘， DEAF-cellulose與Sephadex柱層分析，純化　-澱粉?達純一。此?分子量較小，經估計約為
  20,000道爾頓，且由單一種多胜所構成。此?之最適作用pH在7.0，在45　C時活性最強。在酵素動力學上之探討顯示
  ，其以可溶澱粉當作受質時， Km 約為0.023%。經以Ca ，Cu ，Mg ，Zn ，Mn ，Ba ，Co 及數種其他離子（
  最終濃度5.0 mM）測試，未發現有其反應所必需者。
  K
• 英文摘要： The phytopathogenic bacterium Xanthomonas campestris pv. campestris grows very well in a me-dium containing starch as the sole carbon source. The ability of the microorganism to grow on starch isdue to the induction of an extracellular -amylase. Maltose induces it to synthesize even higher levels ofthe enzyme than those in starch-grown cells; however, a distinct maltase activity is present intracellularly.The -amylase activity was recovered from the culture fluid and purified to apparent homogeneity by u1-trafiltration, DEAE-cellulose and Sephadex column chromatographies. A relatively small molecular weightof the enzyme was calculated to be approximately 20,000 and contains only one kind of peptide chain.The enzyme has a pH optimum at 7.0 and exhibits maximal activity at 45 C. Measurements of substratesaturation kinetics showed that the enzyme has a Km of 0.023% with soluble starch as the substrate understandard assay conditions. Ca , Cu , Mg , Zn , Mn , Ba , Co and other ions (at 5.0 mM final con-centration) were tested and none were found to be required for the enzyme activity.
• 中文關鍵字： α-amylase; sharch; maltose; induction; culture fluid; purified; column chromatography; Km; enzyme activity.
• 英文關鍵字： --