| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 97 === Cyanophycin is a water-insoluble reserve polymer of cyanobacteria, and is a product of nonribosomal peptide synthesis. We used recombinant Escherichia coli to produce cyanophycin, and extracted cyanophycin from the cells by the acid extraction method, and then analyzed its amino acids composition by high performance liquid chromatography.
In order to increase the cyanophycin yield, we supplemented additional amino acids in the medium when induction. After the addition of amino acids, the yield increased from 1.3~1.4% (w/w) to nearly 3.5% (w/w).
The results of high performance liquid chromatography analysis showed that the composition of amino acids is arginine : aspartic acid approximately 1 : 1, and the content of lysine is very low, almost undetectable.
Another aim of this study is to measure the physical properties of cyanophycin. We used differential scanning calorimeter, fourier transform infrared spectrometer and thermogravimetry analysis. We found the melting point of cyanophycin is approximately 196°C, and pyrolysis temperature is 246°C.
We also used cyanophycin to prepare membranes, and used fourier transform infrared spectrometer to analyze its function groups. We found that the spectra of the cyanophycin powder and membrane are almost the same. The contact angle of cyanophycin membrane prepared with 0.1N HCl is 63°, and the contact angle of cyanophycin membrane prepared with 0.1N HCl / methanol is 66°.
We also added amino acids in different ratios. The analysis of differential scanning calorimeter and sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that different ratios had no effect on the structure of chyanophycin.
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