title: Collagens from the skin of arabesque greenling (Pleurogrammus azonus) solubilized with the aid of acetic acid and pepsin from albacore tuna (Thunnus alalunga) stomach.
abstract: BACKGROUND
  Due to the low extraction efficiency of collagen from fish skin by the typical acid solubilization process, pepsin has been widely used to aid further extraction of collagen from the residue. The aim of this study was to characterize collagen from the skin of arabesque greenling extracted with the aid of albacore tuna pepsin, in comparison with collagen obtained from the acid solubilization process.
  
  
  RESULTS
  Acid-solubilized collagen (ASC) from the skin of arabesque greenling was extracted with acetic acid. Pepsin-solubilized collagen (PSC) was further extracted from the skin residue with the aid of pepsin from albacore tuna. The yields of ASC and PSC were 303 and 140 g kg(-1) (dry weight), respectively. Both collagens contained alpha- and beta-chains as their major components and were characterized as type I collagen. Both collagens contained glycine as a major amino acid and had imino acid content of 157-159 residues per 1000 residues. The degradation induced by lysyl endopeptidase and V8-protease was more pronounced in PSC compared with ASC. Maximal transition temperatures of both collagens were in the range of 15.4-15.7 degrees C. Fourier transform infrared spectra revealed some differences in molecular order between ASC and PSC. Nevertheless, the triple-helical structure of PSC was still predominant. Based on zeta-potential, pI of ASC and PSC was estimated to be 6.31 and 6.38, respectively.
  
  
  CONCLUSIONS
  Isolation of collagens from the skin of arabesque greenling could be achieved by acid or albacore tuna pepsin solubilization. However, there was a slight difference in properties between ASC and PSC.
authors.affiliation: Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
authors.forename: Sitthipong
authors.initials: S
authors.lastname: Nalinanon
authors.forename: Soottawat
authors.initials: S
authors.lastname: Benjakul
authors.forename: Hideki
authors.initials: H
authors.lastname: Kishimura
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D024042:Collagen Type I / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D029941:Fish Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D005511:Food Handling / Q000379:methods; D007220:Industrial Waste / Q000032:analysis / Q000191:economics; D007526:Isoelectric Point; D008970:Molecular Weight; D010434:Pepsin A / Q000302:isolation & purification / Q000378:metabolism*; D010449:Peptide Mapping; D010473:Perciformes; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry; D012867:Skin / Q000737:chemistry*; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013270:Stomach / Q000201:enzymology*; D044366:Transition Temperature; D014413:Tuna
chemical_list: D000596:Amino Acids; D024042:Collagen Type I; D029941:Fish Proteins; D007220:Industrial Waste; D021122:Protein Subunits; D010434:Pepsin A; D019342:Acetic Acid