322
the “[Gly-3Hyp-4Hyp] motif is predisposed for silica precipitation, and provides a
novel template for biosilicifi cation in nature,” (Ehrlich et al. 2010 ).
Intriguingly, the deep-sea glass sponges habituate in aquatic niches with temperatures between −1.5 and 4 °C. Therefore, we can hypothesize that hydroxylated collagen could play an important role as a scaffold and/or as a template for biosilicifi cation
at temperatures near 0 °C; i.e., in extremely cold aquatic environments. However, the
mechanism of this “ psychrophilic biosilicifi cation ” is still unknown. It is well
accepted that antifreeze proteins (AFPs) enable organisms to avoid freezing under
extreme conditions. These proteins have been reported in bacteria, insects, fi sh, and
other organisms that need to survive in cold temperatures (see for review Venkatesh
and Dayananda 2008 ). AFPs protect the organisms by arresting the growth of ice
crystals in their bodies. Interestingly, there are no reports on possible role of these
proteins in biomineralization phenomena, including both collagen- based biosilicifi -
cation and calcifi cation. While the amino-acid composition and thermal stability of
the skin collagen of the Antarctic ice-fi sh is well known (Rigby 1968 ), there is a lack
of knowledge regarding the role of this collagen in biomineralazation. From this
point of view, different species of Antarctic ice fi shes seems to be appropriate model
organisms to study collagen-based calcifi cation under extremely cold conditions.
If we understand the principles of collagen chemistry, as well as the structural
organization underlying survival at these freezing temperatures, then it is almost
certain that we will understand how to create and establish the principles of Extreme
Biomimetics using collagenous templates (Ehrlich 2012 ).
Thus, we can defi ne three main categories of marine collagens: collagens of
invertebrate origin, fi sh collagens, and marine mammal collagens. Marine fi sh collagens isolated from skin, meat, scales, fi ns and waste materials are especially of
interest from industrial point of view (see also Chap. 12.1 in this work).
8.1 Isolation and Properties of Fish Collagens
Type I, type II, type V/XI and type XVIII genes encoding collagens have been identifi ed in fi sh (see for review Guellec et al. 2004 ). “The number of published
sequences is still limited, but additional sequences are available in databases. The
comparison between fi sh and tetrapod collagen sequences indicates that the main
characteristics of collagens were conserved during vertebrate evolution. In skin and
intramuscular connective tissue of fi sh, type I and type V collagens have been identifi ed as the major and minor collagen respectively,” (Guellec et al. 2004 ). As
reviewed by Eastoe ( 1957 ), amino acid analyses of fi sh collagens have been reported
by Beveridge and Lucas ( 1944 ), who used mainly gravimetric methods, for isinglass from the swim bladder of hake (Urophyci); by Block, Horwith and Bolling in
1949 for the scales of herring (Clupea) and by Neuman in 1949, who used microbiological- assay techniques, for halibut skin and for gelatin prepared from the scales
of an unspecifi ed fi sh. Amino acid composition of fi sh collagens has been also studied by Piez and Gross ( 1960 ). Fish collagens and gelatins resemble those of mammals (Eastoe 1957 ) in that they contain the same amino acids in, broadly speaking,
8 Marine Collagens
the “[Gly-3Hyp-4Hyp] motif is predisposed for silica precipitation, and provides a
novel template for biosilicifi cation in nature,” (Ehrlich et al. 2010 ).
Intriguingly, the deep-sea glass sponges habituate in aquatic niches with temperatures between −1.5 and 4 °C. Therefore, we can hypothesize that hydroxylated collagen could play an important role as a scaffold and/or as a template for biosilicifi cation
at temperatures near 0 °C; i.e., in extremely cold aquatic environments. However, the
mechanism of this “ psychrophilic biosilicifi cation ” is still unknown. It is well
accepted that antifreeze proteins (AFPs) enable organisms to avoid freezing under
extreme conditions. These proteins have been reported in bacteria, insects, fi sh, and
other organisms that need to survive in cold temperatures (see for review Venkatesh
and Dayananda 2008 ). AFPs protect the organisms by arresting the growth of ice
crystals in their bodies. Interestingly, there are no reports on possible role of these
proteins in biomineralization phenomena, including both collagen- based biosilicifi -
cation and calcifi cation. While the amino-acid composition and thermal stability of
the skin collagen of the Antarctic ice-fi sh is well known (Rigby 1968 ), there is a lack
of knowledge regarding the role of this collagen in biomineralazation. From this
point of view, different species of Antarctic ice fi shes seems to be appropriate model
organisms to study collagen-based calcifi cation under extremely cold conditions.
If we understand the principles of collagen chemistry, as well as the structural
organization underlying survival at these freezing temperatures, then it is almost
certain that we will understand how to create and establish the principles of Extreme
Biomimetics using collagenous templates (Ehrlich 2012 ).
Thus, we can defi ne three main categories of marine collagens: collagens of
invertebrate origin, fi sh collagens, and marine mammal collagens. Marine fi sh collagens isolated from skin, meat, scales, fi ns and waste materials are especially of
interest from industrial point of view (see also Chap. 12.1 in this work).
8.1 Isolation and Properties of Fish Collagens
Type I, type II, type V/XI and type XVIII genes encoding collagens have been identifi ed in fi sh (see for review Guellec et al. 2004 ). “The number of published
sequences is still limited, but additional sequences are available in databases. The
comparison between fi sh and tetrapod collagen sequences indicates that the main
characteristics of collagens were conserved during vertebrate evolution. In skin and
intramuscular connective tissue of fi sh, type I and type V collagens have been identifi ed as the major and minor collagen respectively,” (Guellec et al. 2004 ). As
reviewed by Eastoe ( 1957 ), amino acid analyses of fi sh collagens have been reported
by Beveridge and Lucas ( 1944 ), who used mainly gravimetric methods, for isinglass from the swim bladder of hake (Urophyci); by Block, Horwith and Bolling in
1949 for the scales of herring (Clupea) and by Neuman in 1949, who used microbiological- assay techniques, for halibut skin and for gelatin prepared from the scales
of an unspecifi ed fi sh. Amino acid composition of fi sh collagens has been also studied by Piez and Gross ( 1960 ). Fish collagens and gelatins resemble those of mammals (Eastoe 1957 ) in that they contain the same amino acids in, broadly speaking,
8 Marine Collagens