title: Tuna pepsin: characteristics and its use for collagen extraction from the skin of threadfin bream (Nemipterus spp.).
abstract: Pepsin from the stomach of albacore tuna, skipjack tuna, and tongol tuna was characterized. Pepsin from all tuna species showed maximal activity at pH 2.0 and 50 degrees C when hemoglobin was used as a substrate. Among the stomach extract of all species tested, that of albacore tuna showed the highest activity (40.55 units/g tissue) (P < 0.05). Substrate-Native-PAGE revealed that pepsin from albacore tuna and tongol tuna consisted of 2 isoforms, whereas pepsin from skipjack tuna had only 1 form. The activity was completely inhibited by pepstatin A, while EDTA (ethylenediaminetetraacetic acid), SBTI (soybean trypsin inhibitor), and E-64 (1-(L-trans-epoxysuccinyl-leucylamino)-4-guanidinobutane) exhibited negligible effect. The activity was strongly inhibited by SDS (sodium dodecyl sulfate) (0.05% to 0.1%, w/v). Cysteine (5 to 50 mM) also showed an inhibitory effect in a concentration dependent manner. ATP, molybdate, NaCl, MgCl(2), and CaCl(2) had no impact on the activity. When tuna pepsin (10 units/g defatted skin) was used for collagen extraction from the skin of threadfin bream for 12 h, the yield of collagen increased by 1.84- to 2.32-fold and albacore pepsin showed the comparable extraction efficacy to porcine pepsin. The yield generally increased with increasing extraction time (P < 0.05). All collagen obtained with the aid of tuna pepsin showed similar protein patterns compared with those found in acid-solubilized collagen. Nevertheless, pepsin from skipjack tuna caused the degradation of alpha and beta components. All collagens were classified as type I with large portion of beta-chain. However, proteins with molecular weight (MW) greater than 200 kDa were abundant in acid-solubilized collagen.
authors.affiliation: Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, 90112, Thailand.
authors.forename: S
authors.initials: S
authors.lastname: Nalinanon
authors.forename: S
authors.initials: S
authors.lastname: Benjakul
authors.forename: W
authors.initials: W
authors.lastname: Visessanguan
authors.forename: H
authors.initials: H
authors.lastname: Kishimura
mesh_terms: D000818:Animals; D003094:Collagen / Q000737:chemistry / Q000187:drug effects* / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes; D008970:Molecular Weight; D010434:Pepsin A / Q000494:pharmacology*; D010473:Perciformes; D011489:Protein Denaturation / Q000187:drug effects; D013270:Stomach / Q000201:enzymology*; D013696:Temperature; D014361:Trypsin Inhibitors / Q000494:pharmacology*; D014413:Tuna / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D014361:Trypsin Inhibitors; D003094:Collagen; D010434:Pepsin A