Food Biochemistry and Food Processing (2 edition)

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20 Fish Collagen 377

205 kDa

Nonreducing Reducing

γγ

β

α 1 (α 3 )

116 kDa α 2

97.4 kDa

66 kDa

MIIISB SB III V

Figure 20.5.SDS–PAGE patterns of collagen from the skin (S) and bone (B) of bigeye snapper under reducing and nonreducing conditions.

M, I, II, III, and V denote high molecular weight protein markers, and collagens type I, II, III, and V, respectively (Kittiphattanabawon et al.

2005).

18-month steer was 3.2%. Similar trends were also noted in neu-

tral salt-soluble (NSC) and pepsin-treated, acid-soluble (PSC)

fractions. The greater resistance to degradation in biologically

older bovine collagen is thought to be directly related to in-

creased cross-link formation. Gel permeation chromatography,

using a newly developed 03BC-Bondagel column, was found

to provide a rapid means for separation and determination

of molecular size distribution (Miller et al. 1983). Chomarat

et al. (1994) compared the effectiveness of two proteolytic en-

zymes, pepsin and proctase (isolated fromAspergillus niger),

for the solubilization of collagen from bovine skin. Pepsin-

and proctase-solubilized collagens had the similar yields (75%

and 76% of total collagen as calculated from hydroxyproline).

However, proctase-extracted collagen exhibited a decrease in

high-MW components compared with pepsin-extracted colla-

gen (Chomarat et al. 1994).

Collagen was prepared from common minke whale unesu

and characterized (Nagai et al. 2008). The yield of collagen

was high, about 28.4% (wet weight basis). By SDS–PAGE and

TOYOPEARL©RCM-650M column chromatography, the colla-

gen was classified as type I collagen. The denaturation temper-

ature of the collagen was 31.5◦C, about 6–7◦C lower than that

of porcine collagen. Attenuated total reflectance-FTIR analysis

indicated that ASC from common minke whale unesu held its

triple-helical structure well, but the structures of porcine skin

collagen and pepsin-solubilized collagen from common minke

whale were changed slightly because of the loss ofN-and

C-terminus domains (Nagai et al. 2008).

Fish Collagen

Fish collagen from different sources can have different compo-

nents. This may affect the properties of those collagens. Gener-

ally, fish collagens, from both finfish and shellfish, are classified

to be types I and V as a major and minor component, respec-

tively.

Protein Components

Both collagens, from the skin and bone of bigeye snapper

(P. tayenus), comprised at least two differentα-chains,α1 and

α2 (see Fig. 20.5). Theα3-chain, if present, could not be sep-

arated under the electrophoretic conditions employed because

α3(I) migrates electrophoretically to the same position asα1(I)

(Kimura and Ohno 1987, Matsui et al. 1991). Collagen of skin

and bone from other fish species showed the similarity (Kimura

and Ohno 1987, Matsui et al. 1991, Nagai and Suzuki 2000).

The electrophoretic patterns of collagens from the skin and

bone under nonreducing and reducing conditions were simi-

lar, indicating the absence of the disulfide bonds in those col-

lagens. However, peptide maps of collagen from the skin and

bone of bigeye snapper, digested by V8 protease and lysyl