Physicochemical Properties And Structural Characteristics Of Collagen From Grass Carp Of Swimming Bladder

In the process of grass carp, many swimming bladders are discard regard as wasteand scrap. There are large amounts of collagen in swimming bladder, which was widelyused in food, cosmetics as well as biomedical materials based on its natural low toxicity,biodegradability, low immunogenicity, moisture retention and nutrition. In this paper, theextraction process of collagen from swimming bladder of grass carp was explored. Thephysicochemical properties and structural characteristics of collagen were also studied inthe paper. The results provide a theoretical basis on utilization and development incollagen protein extracted from swimming bladder of grass carp. Research contents andresults are as follows:1. Determining the collagen content in swimming bladder. The standard curve ofcollagen was obtained using hydroxyproline. The results showed that there were0.0497g/g of hydroxypro. line and0.5518g/g of collagen in swimming bladder of grass carp.Selection of acetic acid, citric acid, pepsin and composite protease to extract collagenfrom swimming bladder of grass carp, the result showed that used pepsin as extractingreagent was better, reached16.65%.2. Optimizing extraction process of collagen from swimming bladder. Based onsingle factor experiment, response surface methodology was used to optimize the enzymeconcentration, extraction time and liquid-solid ratio in process of extracting PSC fromswimming bladder of grass carp. The optimization results showed that the optimumconditions for enzyme concentration were40mg/g, extraction time was48h, and liquid-solid ratio was80mL/g. The extraction rate of collagen reached17.82%at the optimumcondition. Through the method of salting out, solubilization and refolding of dialysis,pure collagen was available.3. Studying physical and chemical properties of collagen. Analysis of ultravioletscanning spectra showed that collagen from swimming bladder of grass carp has the largest absorb peak at235nm. Analysis of infrared spectroscopy showed that absorbpeaks at3325cm^-1,1653cm^-1, l235cm^-1and l080cm^-1. FT-IR pattern showed that thecollagen has special and complete three spiral structure. Using the analysis method ofSDS-PAGE, electrophoresis revealed extracted collagen has high pure. Collagencomprised a α1chain, a α2chain and a β chain, in which chain of α1was far wider thanchain of α2and the results reveal α3chain may be contained. Collagen was a typical of Icollagen. Viscosity of collagen decreased with temperature increasing and thermaldenaturation temperature of collagen is29.4℃. Through methodof differential scanningcalorimetry, the temperature of thermal shrinkage is42.11℃. Amino acid analysisshowed that glycine content is so high that it occupied21%of total amino acid. Theglutamic, alanine, proline and lysine content are11.03%,12.41%,9.87%and3.12%respectively. According to the results, the content of arginine and histidine is lowest andcysteine and tryptophan were not contained.4. Research on structural of collagen from swimming bladder. Scanning electronmicroscopy of collagen from swimming bladder of grass carp revealed its morphologyinto a fibrous, porous structure, and the aperture is not uniform. The result of X-raydiffraction patterns showed that collagen of swimming bladder has three peaks,indicating it exists two phase structure. The space of collagen molecular chain is1.21nm.Peptide mass fingerprinting showed that collagen from swimming bladder of grass carphas better matching to gi|227908757|ref|NP₀01153141.1|, matching degree up to33.30%, matching with6peptide segment.