Use of pepsin for collagen extraction from the skin of bigeye snapper (Priacanthus tayenus)

Extraction and some properties of pepsin-solubilised collagens from the skin of bigeye snapper (Priacanthus tayenus) were investigated. Addition of bigeye snapper pepsin (BSP) at a level of 20 kUnits/g of defatted skin resulted in an increased content of collagen extracted from bigeye snapper skin. The yields of collagen from bigeye snapper skin extracted for 48 h with acid and with BSP were 5.31% and 18.74% (dry basis), respectively. With pre-swelling in acid for 24 h, collagen extracted with BSP at a level of 20 kUnits/g of defatted skin for 48 h had a yield of 19.79%, which was greater than that of collagen extracted using porcine pepsin at the same level (13.03%). The skin collagen was characterised to be type I with no disulfide bond. Electrophoretic study revealed slight differences in molecular weight between acid-solubilised collagen and all pepsin-solubilised collagens. The molecular weights of al and alpha 2 chains in acid-solubilised collagen were estimated to be 120 and 112 kDa, respectively, whereas a I and a2 chains of pepsin-solubilised collagens had molecular weights of 118 and I I I kDa, respectively. The result suggested that these pepsin-solubilised collagens might undergo partial cleavage in the telopeptide region by pepsin treatment. The maximum transition temperature (T-max) of acid-solubilised collagen was observed at 32.5 degrees C which was slightly higher than that of pepsin-solubilised collagens (by about 1 degrees C). Generally, all collagens were highly solubilised in the pH range of 2-5 and sharply decreased at the neutral pH. No changes in solubility were observed in the presence of NaCl up to 3% (w/v) and the decrease was more pronounced with increasing NaCl concentration. (C) 2006 Elsevier Ltd. All rights reserved.