This document discusses the nutritional qualities of fish and the role of peptides in fish. It defines peptides as short chains of amino acids linked by peptide bonds. It describes several types of peptides found in fish, including antifreezing peptides, natriuretic peptides, and antimicrobial peptides. The document discusses the roles of these peptides, such as antifreezing peptides inhibiting ice crystal growth to allow fish to survive in subzero temperatures. The document also discusses collagen, squalene, and other biochemical components found in fish and their functions.

1. ASSIGNMENT PRESENTATION
OF
FISH IN NUTRITION

3. INTRODUCTION
 The biochemical composition of fish finds application
in several areas today there is an ever increasing
awareness about healthy food and fish is finding more
acceptance because of it special nutritional qualities in
this context a proper understanding about the
biochemical constituents of fish has become a primary
requirement for the nutritionists and dieticians.

4.  Another vital area where accurate information on
biochemical composition is must in processing and
preservation of fish and fishery products fish is an
easily perishable commodity and deterioration in
quality is due to the changes taking place to the
various constituents like protein , lipids etc.
information on the biochemical constituents will help
a processing technologist to define the optimum
processing & storage conditions, so that the quality is
preserved to the maximum extent.

6. PEPTIDES

7. DEFINITION
Peptides (from Gr.: peptós "digest
ed"; derived from péssein "to
digest") are natural biological or
artificially manufactured short
chains of amino
acid monomers linked
by peptide (amide) bonds.

8. A tetrapeptide (example Val-Gly-Ser-Ala)
with green marked amino end (L-Valine) and
blue marked carboxyl end (L-Alanine).

9. CLASSES OF PEPTIDES
Milk peptides
Ribosomal peptides
Non-ribosomal peptides
peptones

10. ROLE OF PEPTIDES IN FISHES
 There are several kind of peptides which are very
necessary & plays an important role in biological
functioning of fishes. These are-
 ANTI-FREEZING PEPTIDE
 NATRIURETIC PEPTIDE
 ANTI-MICROBIAL PEPTIDE

11. ANTI-FREEZING PEPTIDE
 Antifreeze proteins (AFPs) or ice structuring
proteins (ISPs) refer to a class
of polypeptides produced by
certain vertebrates, plants, fungi and bacteria that
permit their survival in subzero environments. AFPs
bind to small ice crystals to inhibit growth
and recrystallization of ice that would otherwise be
fatal. There is also increasing evidence that AFPs
interact with mammalian cell membranes to protect
them from cold damage. This work suggests the
involvement of AFPs in cold acclimatization.

12. The three faces of Type I AFP

13. ANTI-MICROBIAL PROTEIN
 Antimicrobial peptides (AMPs), also called host
defense peptides (HDPs) are part of the innate immune
response found among all classes of life. Fundamental
differences exist between prokaryotic and eukaryotic cells
that may represent targets for antimicrobial peptides.
These peptides are potent, broad
spectrum antibiotics which demonstrate potential as novel
therapeutic agents. Antimicrobial peptides have been
demonstrated to kill Gram negative and Gram
positive bacteria, enveloped viruses, fungi and even
transformed or cancerous cells.Unlike the majority of
conventional antibiotics it appears as though antimicrobial
peptides may also have the ability to enhance immunity by
functioning as immunomodulators.

15. Various structures of antimicrobial peptides Various structures of
antimicrobial peptides

16. Marine fish sources have high
levels of antimicrobial
compounds with in vivo testing
confirming the efficacy of fish
peptides used in food/feed
ingredients.

17. NATRIURETIC PEPTIDE
. Natriuretic peptides exist in the fishes as a family of
structurally-related isohormones including atrial
natriuretic peptide (ANP), C-type natriuretic peptide
(CNP) and ventricular natriuretic peptide (VNP); to
date, brain natriuretic peptide (or B-type natriuretic
peptide, BNP) has not been definitively identified in
the fishes.

18. COLLAGEN

19.  Collagen is the main structural protein in
the extracellular space in the various connective
tissues in animal bodies. As the main component of
connective tissue, it is the most abundant protein in
mammals,making up from 25% to 35% of the whole-
body protein content.

20.  Fish collagen is a protein extracted from fish that is
mainly used as a cosmetic aid to decrease the
appearance of wrinkles. Collagen makes up 30 percent
of the protein in human bodies and can be found in
the skin, joints, teeth, bones, tendons, and blood
vessels. It makes up 70 percent of the protein in the
skin and helps keep it elastic. Collagen also helps keep
the joints fluid, and teeth and bones strong.

21. Fish collagen is extracted from fish skin
& scales.(marine fish collagen)

22. Three polypeptides coil to form tropocollagen. Many
tropocollagens then bind together to form a fibril, and many of
these then form a fibre.

23. Anti-aging tablets

24. SQUALENE

25. Squalene is a natural 30-
carbon organic compound
originally obtained for
commercial purposes primarily
from shark liver oil (hence its
name, as Squalus)

26.  Shark liver oil is an oil obtained from the livers of sharks.
It has been used for centuries as a folk remedy to promote
the healing of wounds and as a remedy for respiratory tract
and digestive system problems. It is still promoted as
a dietary supplement, and additional claims have been
made that it can treat other maladies such as cancer, HIV,
radiation illness, swine flu and the common cold. To date,
none of these claims has been medically validated and
shark liver oil (alone) is not a medication prescribed or
utilized by American physicians.[7] However, it is a
component of some moisturizing skin lotions,[6]and some
hemorrhoid medications.

27. Sharks typically targeted for their liver oil include
the school and gulper shark, and the basking shark

28. Function in the Shark
 Many fish maintain buoyancy with swim bladders.
However sharks lack swim bladders, and maintain
their buoyancy instead with large livers that are full of
oil. This stored oil may also function as a nutrient
when food is scarce. Deep sea sharks are usually
targeted for their oil, because the livers of these
species can account for up to 5-10% of their total
weight.[

29. Medicinal use
 Most shark liver oil supplements have not been tested
to find out if they interact with medicines, foods, or
other herbs and supplements. Even though some
reports of interactions and harmful effects may be
published, full studies of interactions and effects are
not often available. Although many people have taken
shark liver oil, the issue of potential toxicity at the
usual doses has not been well studied. Some mild
digestive problems such as nausea, upset stomach, and
diarrhea have been reported. The safe range of doses
for shark liver oil has not yet being determined,
though overdosing can have toxic consequences

31.  Some animal studies have found that shark liver oil
and its components may raise blood cholesterol levels.
A Japanese study found some shark liver oil
supplements to be contaminated with polychlorinated
biphenyls (PCBs) and polybrominated diphenyl
ethers (PBDEs).PCBs can have harmful effects in
humans, and may increase the risk of some types of
cancer. People with seafood allergies may also react to
shark liver oil.

32.  Shark liver oil has been misleadingly promoted as a
treatment for cancer. Despite claims that the alkoxy-
glycerols derived from shark liver oil could reduce
tumor growth, there is not sufficient evidence to prove
this to be a viable treatment option.