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Proteins
Lucie Kubalová
A protein (in Greek πρωτεϊνη = first element)


is
a
complex,
high
molecular weight organic
compound that consists
of amino acids joined
by peptide bonds.
is
essential
to
the
structure and function
of all living cells and
viruses. Many proteins are
enzymes
or
subunits
of enzymes.
A peptide bond

is a chemical bond formed
between two molecules
when the carboxyl group
of one molecule reacts
with the amino group
of the other molecule,
releasing
a
molecule
of water (H2O). This is
a dehydration synthesis
reaction,
and
usually
occurs
between
amino
acids.
Primary Structure


A
protein
can
be
considered
to
have
primary,
secondary,
tertiary, and quaternary
structures.
primary structure:
the
linear amino acid sequence
of a protein
Secondary

regular
(pravidelný)
repeating
structures
arising
(vznikají)
when
hydrogen bonds between
the
peptide
backbone
amide
hydrogens
and
carbonyl oxygens occur
at regular intervals within
a given linear sequence
(strand) of a protein (as
in
the
alpha
helix)
or between two adjacent
strands (as in beta sheets
and reverse turns)
Tertiary

the overall three dimensional shape of a protein, often
represented by a backbone trace
Quaternary

oligomeric
structure
of
a
multisubunit
protein
in which separate proteins chains associate to form dimers,
trimers, tetramers, and other oligomers. The different
chains in the oligomers may be the same protein
(homooligomers)
or
a
combination
of different protein chains (heteroliogomers).
The
different chains within the oligomer may be held together
by noncovalent intermolecular forces or may also contain
covalent interchain disulfides.
held(hold) = držet
Protein nutrition in humans


proteins come in two forms: complete proteins contain all
eight of the amino acids (threonine, valine, tryptophan,
isoleucine, leucine, lysine, phenylalanine, and methionine)
that humans cannot produce themselves, while incomplete
proteins lack or contain only a very small proportion of one
or more
Humans' bodies can make use of all the amino acids they
extract from food for synthesizing new proteins, but the
inessential ones themselves need not be supplied by the
diet, because our cells can make them ourselves.
proportion = podíl
supply = zásobovat
References:



http://en.wikipedia.org
http://www.healthepic.com
http://employees.csbsju.edu
Thank you very much for your kind
attention