Extraction and characterization of pepsin-soluble collagen from different mantis shrimp species

Abstract

The objective of this study was to investigate the yield and characteristics of collagen protein extracted from the muscle of four different species of mantis shrimp: Miyakella nepa, Harpiosquilla harpax, Erugosquilla woodmasoni, and Odontodactylus cultrifer. Mantis shrimp muscle was extracted by using a pepsin-solubilization technique, with 0.5 M acetic acid and 5% pepsin enzyme. The highest collagen yield was from M. nepa muscle (0.478 ± 0.06%), which was significantly greater (p < 0.05) than that from H. harpax, O. cultrifer, and E. woodmasoni (0.313 ± 0.03%, 0.123 ± 0.02%, and 0.015 ± 0.00%, respectively). The freeze-dried collagen appeared as thin fibers, and formed an opaque film. The pepsin-soluble collagen (PSC) from four mantis shrimp species was analyzed by gel electrophoresis. The results showed that all species of mantis shrimp contained type I collagen, consisting of β, α1, and α2 subunits with average molecular weights of 250, 145, and 118 kDa, respectively. The study of the solubility of collagen showed that, for NaCl, collagen had the highest relative solubility in 2% NaCl (80.20 ± 4.95%). In contrast, the solubility decreased at higher NaCl concentrations. However, in terms of pH, collagen had the highest relative solubility at pH 3 (91.32 ± 5.14%), and its solubility decreased at higher pH. FT-IR spectroscopy was used to compare the collagen with a model compound. Five wavenumbers in the spectrum for model collagen were identified: Amide A (3,406–3,421 cm−1), amide B (2,916–2,940 cm−1), amide I (1,639–1,640 cm−1), amide II (1,539–1,570 cm−1), and amide III (1,234–1,250 cm−1).