Research Article Characteristics of Pepsin-Solubilised Collagen from the Skin of Splendid Squid (Loligo formosana) Phanat Kittiphattanabawon, 1 Sitthipong Nalinanon, 2 Soottawat Benjakul, 3 and Hideki Kishimura 4 1 Department of Food Science and Technology, Faculty of Technology and Community Development, Taksin University, Phatthalung Campus, Phatthalung 93210, Tailand 2 Faculty of Agro-Industry, King Mongkut’s Institute of Technology Ladkrabang, Ladkrabang, Bangkok 10520, Tailand 3 Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90112, Tailand 4 Laboratory of Marine Products and Food Science, Research Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan Correspondence should be addressed to Sitthipong Nalinanon; sitthipong.na@kmitl.ac.th Received 12 October 2015; Accepted 7 December 2015 Academic Editor: Murat Senturk Copyright © 2015 Phanat Kittiphattanabawon et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Pepsin-solubilised collagen from the skin of splendid squid (SC) was isolated, partially purifed by salt precipitation and dialysis prior to characterisation. Te yield of SC was 75.3% (dry weight basis). SC with high purity was obtained as shown by the distinct UV absorption peak at 232nm and high hydroxyproline content. Total sugar content of SC was 4.70% (dry weight basis), which was higher than that of collagen from calf skin (CC) (1.45% dry weight basis) ( < 0.05). Based on SDS-PAGE and elution profle, SC might contain the mixed types of collagen (type SQ-I and type SQ-II), in which - and -chains were the major components. SC was rich in glycine and had high content of imino acids (189 residues/1000 residues). Te degradation induced by chymotrypsin and lysyl endopeptidase was more pronounced in CC, compared with SC. Te maximum transition temperature ( max ) of SC was 34.1 ∘ C, which was about 7 ∘ C lower than that of CC. Fourier transform infrared spectra revealed that the triple-helical structure of SC was predominant with the copresence of carbohydrate moieties. Terefore, the skin of splendid squid, a byproduct from squid processing, can be an alternative source for collagen production. 1. Introduction Collagen is the fbrous protein that contributes to the unique physiological functions of connective tissues in skins, ten- dons, bones, cartilages, and so forth and is associated with toughness of mammalian muscle [1–3]. Te structural unit of collagen is tropocollagen, a rod-shaped protein consisting of three polypeptides units (called  chains) intertwined to form a triple-helical structure [4]. Each polypeptide chain forms a lef-handed helix and consists of repeating triplets (Gly-- ) n , where  and  are, with a high possibility, proline or hydroxyproline [5]. Generally, pig and cow skins and bones are the main sources of collagen and gelatin. Te outbreak of bovine spongiform encephalopathy (BSE) has resulted in anxiety among users of cattle gelatin. Additionally, the collagen and gelatin obtained from pig skin and bones cannot be used due to the religious constraint [6]. As a consequence, the increasing attention of alternative sources for replacement of mammalian collagen has been paid. Seafood processing byproducts, particularly the skins, are alternative sources for collagen preparation. Collagens from several fsh and cephalopods such as unicorn leatherjacket [7], arabesque greenling [8], brownbanded bamboo shark [2], cod [9], deep- sea redfsh [10], bigeye snapper [11, 12], black drum [5], sheephead seabream [5], octopus [13], and cuttlefsh [14] have been isolated and characterised. Squids have become an important fshery product in Tailand as well as other Southeast Asian countries and are mainly exported worldwide [15]. From the squid processing, Hindawi Publishing Corporation Journal of Chemistry Volume 2015, Article ID 482354, 8 pages http://dx.doi.org/10.1155/2015/482354