Kutum (Rutilus frisii Kutum) is the most
important fish caught around Caspian Sea coastal. It
takes over 50% of the total bony fish catch (5 to 6 thousand tons per year), and provided more than 60% of the
fisherman’s income and is considered
one of the most valuable fishes in the country (ABD &
Ghaninezhad, 2007; Arabi, Sedaghat,
Hoseini, & Fakhri, 2012; Bandpei et al., 2010)
This fish also contributes significantly to the commercial fishery of other
countries bordering the Caspian Sea (Kuliev, 1997).
Kutum is a migratory anadromous fish (Berg, 1962). In March and April, R.
f. Kutum migrates from Iranian Caspian Sea waters into the rivers to
Spawn (Arabi et al., 2012; BAndpei, MAshhor,
Abdolmalaki, & El-Sayed, 2009). This species has a life span of 9-10 years in southern part
of Caspian Sea with males and females attaining sexual maturity between 2-3 and
3-4 years, respectively (ABD & Ghaninezhad, 2007).
Rutilus frisii Kutum is a short lived fast growing species. This
species is normally a medium-sized fish, typically reaching 45-70 cm in length,
weighing up to 5 kg. This fish is harvested commercially (Valipour, Kanipour, KhadiviNiaMoghaddam, & Valinassab,
2011) and due to large amounts of
catch, a significant amount of viscera is produced and generally dumped in-land
or disposed into rivers.
Fish viscera, as a by-product including 5% of
total mass, have wide biotechnological potential as a source of digestive
enzymes like trypsin (Ben Khaled et al., 2008; Bezerra et al., 2005; Castillo-Yánez, Pacheco-Aguilar,
García-Carreño, & de los Ángeles Navarrete-Del, 2005; Khantaphant & Benjakul, 2010; Kishimura & Hayashi, 2002; Lu et al., 2008; Shahidi & Kamil,
2001; Sila et al., 2012).
Various digestive proteases such as aspartic protease pepsin and serine
proteases – trypsin, chymotrypsin, and elastase – are isolated and
characterized from a wide range of cold-water and warm-water fishes including Grey triggerfish
(Balistes capriscus): (Jellouli et al., 2009) ; the spleen of skipjack tuna
(Katsuwonus pelanis): (Sappasith Klomklao, Benjakul, Visessanguan, Kishimura, & Simpson,
2007); true sardine (Sardinops
melanostictus): (Kishimura, Hayashi, Miyashita, & Nonami, 2006); Monterey
sardine (Sardinops sagax caerulea): (Castillo-Yánez et al., 2005); chinook
salmon (Oncorhynchus tshawytscha): (Kurtovic, Marshall, & Simpson, 2006);
walleye pollock (Theragra chalcogramma): (Kishimura, Klomklao, Benjakul, & Chun, 2008) and etc. Proteases represent an
important class of industrial enzymes, accounting about 50% of the total sale
of the enzymes in the world (Souza, Amaral, Santo, Carvalho, & Bezerra, 2007).
(EC 126.96.36.199) is one of the important serine proteases. This endopeptidase
hydrolyzes peptide bonds at the carboxylic end of lysine and arginine residues (S. Klomklao, Kishimura, & Benjakul, 2009). It has a molecular weight ranging from 22 to 28
kDa. Trypsin has practical applications in different industries—such as the
food industry comprising baked foods, beer, wine, cereal, meat and fish
products, production of protein hydrolysates and flavor extract; pharmaceutical;
in diabetes diagnosis and therapy; detergents; leather and silk industry; cell
culture and the production of recombinant proteins (Khantaphant & Benjakul, 2010).