Characteristics of collagen from the skin of clown featherback (Chitala ornata)

Acid soluble collagen (ASC) and pepsin soluble collagen (PSC) from the skin of clown featherback (Chitala ornata) were isolated and characterised. Yields of ASC and PSC were 27.64 and 44.63% (dry weight basis) with total collagen recovery of 82.08%. Both collagens contained glycine as the major amino acid with relatively high content of proline, hydroxyproline and glutamic acid/glutamine. Nevertheless, they had the low content of cysteine, histidine and tryrosine. The collagen was characterised as type I, comprising (α1)₂α2‐heterotrimer. Pepsin‐aided process did not affect triple‐helical structure of PSC as determined by FTIR spectra. Thermal transition temperature of ASC (36.28 °C) was slightly higher than that of PSC (35.23 °C). However, no differences in isoelectric point (5.54–5.68) between ASC and PSC were observed. Therefore, collagen from the skin of clown featherback could be successfully extracted for further applications.     

Temperature effects on type I pepsin‐solubilised collagen extraction from silver‐line grunt skin and its in vitro fibril self‐assembly

BACKGROUND: Fish skin is a potential source of collagen. Increasing the extraction temperature increases the yield of collagen. However, it may also result in degradation of the peptide chains, thus damaging the 3D structure of collagen that is vital for its application as a biomaterial. This work investigated the effects of extraction temperature on the yield and characteristics, including fibril self‐assembly, of type I pepsin‐solubilised fish skin collagen. RESULTS: Pepsin‐solubilised collagens were extracted from fresh skin of silver‐line grunt at 4, 10, 20 and 28 °C for 6 h. Extraction at 10 °C gave the highest yield of collagens (439.32 ± 96.43 mg g^?1 fresh skin, dry basis), which were identified as type I and comprised β, α1 and α2 subunits. Extraction at higher temperatures (20 and 28 °C) resulted in the formation of low‐molecular‐weight peptide fragments, thus reducing the yield of the resultant type I collagen. The denaturation temperatures of collagens extracted at 4 and 10 °C, as determined by thermal analysis using differential scanning calorimetry, were 39.5 and 37.5 °C respectively. In vitro fibril self‐assembly of 1 mg mL^?1 collagen solution (pH 6) incubated at 25 °C was only observed with collagens extracted at 4 and 10 °C. The 10 °C collagen not only showed a higher rate of self‐assembly, but its matrix also had a larger fibril diameter of 0.50 ± 0.07 µm (compared with 0.41 ± 0.07 µm for the 4 °C collagen) after 4 h of incubation. CONCLUSION: The results indicated strong effects of extraction temperature on the yield and characteristics of the collagen obtained. Extraction of pepsin‐solubilised collagen from silver‐line grunt skin at 4–10 °C gave a high yield of type I collagen with molecular integrity suitable for tissue‐engineering applications. Copyright © 2010 Society of Chemical Industry