Physical Properties of fractionated cyanophycin prepared with recombinant Escherichia coli at different temperatures
碩士 === 國立臺灣科技大學 === 化學工程系 === 104 === Cyanophycin is a nonribosomally synthesized biopolymer, and was originally discovered in cyanobacteria about 100 years ago. The structure of natural cyanophycin consists of aspartic acid and arginine, and is arranged as an aspartic acid backbone with an arginine...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2016
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| Online Access: | http://ndltd.ncl.edu.tw/handle/46845520592873094079 |
| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 104 === Cyanophycin is a nonribosomally synthesized biopolymer, and was originally discovered in cyanobacteria about 100 years ago. The structure of natural cyanophycin consists of aspartic acid and arginine, and is arranged as an aspartic acid backbone with an arginine side chain which is linked to the β-carboxyl group of each aspartate by its α-amino group. The gene transformed into microorganisms can be used to produce large amounts of cyanophycin.
In this study, we used Escherichia coli containing Synechocystis sp. PCC 6803 cphA on BL21-CodonPlus(DE3)-RIL to produce cyanophycin. E. coli was cultivated at different temperatures in order to find an optimal condition for cyanophycin production. The molecular weight distribution of cyanophycin has a wide range. We used solvents with different polarity to separate cyanophycin. Soluble cyanophycin was further separated in a solution containing ethanol. Insoluble cyanophycin are further separated at different pH values. The analysis of physical properties of the fractionated cyanophycin was also carried out.
The results showed that the yield of soluble/insoluble cyanophycin ratio at 27 oC is higher than at other temperatures. Fractionated cyanophycin by a low polarity solution showed that the amino acid compositions as Asp：Arg：Lys = 52.62±0.55% : 23.68±1.00% : 23.70±0.76%; fractionated cyanophycin by a high polarity solution showed the amino acid compositions as Asp：Arg：Lys = 50.79±0.78% : 21.21±0.56% : 28.01±0.41%. However fractionated cyanophycin by pH 4 solution showed that the amino acid compositions as Asp：Arg：Lys = 52.15±0.82% : 41.82±0.68% : 6.03±0.40%; fractionated cyanophycin by pH 5 solution showed that the amino acid compositions as Asp：Arg：Lys = 51.21±0.32% : 40.52±0.09% : 8.27±0.25%. Both the soluble and insoluble cyanophycin are thermoresponsive polymers. The phase transitions were observed at different temperatures.
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