離胺酸異構酶與鳥胺酸異構酶S次單元之交互作用

The interaction between lysine 5,6-aminomutase and the S subunit of D-ornithine 4,5-aminomutase

曾振興(Cheng-Hsing Tseng)

指導教授 ： 陳灝平

國立臺北科技大學/工程學院/生物科技研究所/碩士(2007年)

https://doi.org/10.6841/NTUT.2007.00050

摘要

Clostridium sticklandii此菌株內的離胺酸異構酶（lysine 5,6-aminomutase）可將D-α-lysine催化成2,5-diaminohexanoic acid。離胺酸異構酶目前已有二個基因，kamD與kamE被選殖出來，KamD由516個胺基酸所組成，分子量為51,000 Da；KamE由262個胺基酸所組成，分子量為30,000 Da。KamDE在催化的過程中，需要B6及B12兩個輔酶參與反應。前人的研究結果顯示，ATP、金屬離子、丙酮酸 ( pyruvate ) ….等分子對離胺酸異構酶皆有異位調節之功能。但近期的研究卻發現，ATP對於重組酵素KamDE並沒有異位調節的效果。本篇論文的結果顯示，KamDE與鳥胺酸異構酶S次單元（OraS）能夠形成複合體。此外，當ATP及OraS存在的情況之下，可以提高離胺酸異構酶催化活性，並且也使離胺酸異構酶對輔酶B6及B12之Km值分別由3.9降至2.4 μM；6.1降至1.9 μM。在研究中也發現，銨根離子可進一步提高OraS-KamDE這個重組複合體酵素的催化活性。

關鍵字

輔酶B12 ； 離胺酸異構酶鳥胺酸異構酶OraS

並列摘要

Lysine 5,6-aminomutase from Clostridium sticklandii catalyzes the 1,2-rearrangement of D-α-lystine to 2,5-diaminohexanoic acid. Two different genes, kamD and kamE, have been coloned, sequenced and over-expressed in E. coli. The kamD gene, which encodes a protein of 516 amino acid residues with Mr 51,000, and kamE gene, which encodes a protein of 262 amino acid residues with Mr 30,000. Two different coenzymes, pyridoxal phosphate (PLP) and adenosylcobalamin (Ado-Cbl), are involved in this enzymatic reaction. According to pervious studies, lysine aminomutase is an ATP-dependent allosteric enzyme, but recent studies have indicated that ATP no longer has a regulatory effect on the recombinant enzyme, KamDE. In this study, my results demonstrate that the S subunit of D-ornithine aminomutase, OraS, is capable of forming complex with KamDE. ATP and OraS not only lowered the Km of lysine 5,6-aminomutase for AdoCbl from 6.1 to 1.9 μM, and Km for PLP from 3.9 to 2.4 μM, respectively, but also enchanced the enzymatic activity. Finally, the experimental result showed that the activity of reconstituted OraS-KamDE can also be activated by ammonium ion.

並列關鍵字

AdoCbl ； lysine aminomutase ； ornithine aminomutase ； OraS

參考文獻

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