Protein: structure, classification,function and assay methods
Proteins & amino acids (ulivina pratini)
1. AMINO ACIDS &
PROTEINS
Ulivina Pratini
127795086
Science Education
Post Graduate Program
The State University Of Surabaya
2. Learning objectives
1. Understanding the meaning of protein and
amino acids as well as its function
2. Explain review the outline of the
decomposition of proteins for the body
3. Describes several types of metabolic
reactions of amino acids
4. Describes the urea cycle
5. Understanding the biosynthesis of proteins
3. Introduction of Proteins
The proteins in the cells of the body is formed by amino
acids.
The Structure Of Amino Acids
in other words, amino acids are the monomers (units of
Shaper) protein
4. The Structure Of
Amino Acids
From this general formula can be seen that the α-
carbon atom is an asymmetric carbon atom.
consisting of an amine group, a carboxyl group, and a
group of -R (side chain ) that are bound to the same
carbon atom.
5. The Fischer
projection formulas
D-gliseraldehid
Due to the asymmetric carbon, then the amino acid molecule has two
configurations D and L. it can be compared to the molecular configuration
of monosaccharides.
• D (destrorotatory )configuration when the position of the -NH2 group
on the right of the α-carbon atom
• L (levorotatory) configuration when the position of the -NH2 group on
the Left of the α-carbon atom
These amino acids found in proteins generally have configuration L
6. Properties of Amino Acids
When the amino acid is soluble in water, a carboxylic group will release H+
ions, whereas amine groups will receive the H+ ions, as written below.
By the presence of both the Group of amino acids in aqueous solution can
form a positively charged ions and negatively charged ions (zwitterionic)
or an amphoteric substance.
7. The State of this ion strongly depends on the pH
of the solution.
In a State of bases, amino acids will form as
shown below:
because of the concentration of OH- are
high which is able to bind H + ions that are
present in the – NH3 + groups
In a State of Acid, amino acids will form as shown below:
Because the concentration of H + ion is
high, it is able to bind with ion – COO-,
Thus was formed –COOH groups
8. Classification
Based on the formation of amino acids can be divided into two
classes:
1. Essential amino acids (which cannot be produced by the body)
2. Non-essential amino acids (which can be made in the body)
In addition these amino acids can also be grouped according to
the structure of the side chains i.e.
1. the carbon-chain aliphatic
2. Contain hydroxyl groups
3. Contain sulfur atoms
4. Containing acid groups or amida groups
5. Contain a base groups
6. Contain aromatic rings
7. form a bond with the amino group on the N atom
15. 7. Form a bond with the amino group on the N atom
16. Peptide
Some amino acid molecules can bind to one another to form a compound
called peptide.
When the amount of amino acids that are formed more than ten then it is
called polypeptide
Protein is a polypeptide comprising more than a hundred amino acids
18. Example
The name of the peptide is given based on the type of
amino acid that formed it.
Amino acids which the carboxyl group react with the NH2
group – given the suffix “il” in their names,
while the order of naming is based on amino acid
sequence, starting from the ends of the amino acid which
still have the -NH2 group.
or it can be abbreviated as follows : gly-ala-OH
19. Protein
Protein is a polypeptide has a molecular weights vary
widely, from 5000 to over one million. In addition to
different molecular weight proteins have different
properties.
Protein Structure
There are four levels of the basic structure of the
protein, i.e.,
-primary structure,
-secondary,
-tertiary, and
-kuartener.
20. Primary
Structure Primary structure indicate the number, types and
order of amino acids in protein molecules.
The primary structure of the enzyme Ribonuclease
21. Secondary Structure
Polypeptide chains composed of many
>C=O and >N-H groups.
Both of these groups can remain bound to
each other due to the formation of
hydrogen bonds between the oxygen atoms
of the > C = O with a hydrogen atom from
the >N-H group.
When these hydrogen bonds formed
between the cluster-cluster which is
contained in a single polypeptide chain, will
form the structure of the Helix.
as it looks on the picture beside: The structure of a polypeptide Alpha Helix
22. Secondary Structure
These hydrogen bonds can also occur between two or more polypeptide
chains and will form a configuration of α is not a form of parallel helical
winding but chains and called pleated sheet structure
There are two forms of pleated sheet structure, i.e. parallel and anti
parallel
Parallel forms occur when the
polypeptide chains bonded
through hydrogen bonding that is
parallel and in the same direction,
Pleated sheet structure parallel
23. Secondary Structure
Pleated sheet structure non parallel
The non-parallel form occurs if
monomers bound in a position
parallel but opposite in
direction.
24. Tertiary Structure
Tertiary structure shows a tendency to form the polypeptide folds
or rolls, and thus form a more complex structure. The structure is
established by the existence of multiple bonds between R group of
amino acids that make up proteins.
Some types of bonds are for
example:
(a) electrostatic bonding,
(b) hydrogen bonding,
(c) the interaction between the
hydrophobic side chains of non
polar,
(d) the interaction of Dipole-
Dipole and
(e) bonds of disulfide which is a
covalent bond
25. Kuartener Structure
Three-dimensional Model appears as in Figure 1.6 indicates the degree of
participation of units of protein. Most of the globular proteins consist of
several separate polypeptide chains.
This polypeptide chains interacting to form
Alliance, The Figure 1.7 shows a model of
the structure of kuartener which consists of
two globular protein units
Figure 1.6.
Globular protein complex folds
Figure 1.7. The structure of the globular
protein complex kuartener
26. Classification of proteins
Review of the structure of proteins can be divided into major groups, namely
the simple proteins and combined protein
1. Simple proteins are proteins made up of amino acid molecules
Simple Proteins can be divided in two parts according to the shape of the
molecule, namely protein fiber and protein globular. Protein fiber has long
molecular shape as fiber or protein fibers, whereas globular round.
Figur 1.8. The triple helix structure
2. Combined protein is a protein consisting of protein and non protein group.
This group is called prosthetic group and consists of carbohydrates, lipids, or
nucleic acids. Such as: Mukoprotein, glycoproteins, lipoproteins,
nukleoprotein
27. METABOLISM OF PROTEINS AND
AMINO ACIDS
The proteins in our bodies undergoes certain changes with different speeds for
each protein. Daily, 1.2 grams the average of protein per kilogram of body
weight is converted into other compounds.
There are three possible mechanisms of conversion of the protein that is:
1. Dead cells, then its components undergoes decomposition or
catabolism and formed new cells
2. Each protein undergoes the process of decomposition and occur a
new protein synthesis, without any cells that die.
3. Protein secreted from the cell is replaced with a new protein
synthesis
29. Digestion Of Proteins
1. Protein digestion starts in the
stomach with the help of pepsin,
proteolytic enzymes that hydrolyze
peptide bonds on the phenylalanine
residues of amino, tyrosine and
tryptophan
2. The resulting short polypeptide
then enters into the small intestine
where digestion of protein is
continued by trypsin, chymotrypsin,
aminopeptidase, and carboxy-
peptidase that produced amino acids.
3. The resulting amino acid is then
transported through the membrane
of the small intestine into the
bloodstream.
4. Blood distributes amino acids to peripheral tissues for synthesis of proteins and to the
liver to untangle.
30. Metabolism of Amino Acid
The early stages of the reaction of amino acid metabolism involves:
1. Release of the amino group, and then
2. Changes to a new framework on carbon molecules of amino acids.
1. Two core processes of Release the amino group i.e. Transamination and
deamination will be discussed as follows:
1.a. Transamination is the process of catabolism of amino acids that
involves the transfer of amino acids from one amino acid to another amino
acid.
In this transamination reaction of the amino group of an amino acid is
transferred to one of three keto compound, namely pyruvic acid, Alpha
ketoglutarate or oksaloasetat, so this keto compound converted into amino
acids, whereas the original amino acid is converted into an acid keto.
31. Transamination
There are two important enzyme in reactions of
transaminasi i.e. alanin transaminase reactions and
glutamate transaminase reactions that works as a catalyst
in the following reaction:
This reaction occurs in the mitochondria or in liquid cytoplasm
32. Oxidative Deamination
In this process the amino group of glutamic acid release in
the form of NH4+, in addition to NAD+ glutamate
dehidrogenasi can also use NADP+ as an electron acceptor.
Because glutamate is the end result of the process of
transamination, then the glutamate dehydrogenase is an
enzyme which is essential in the metabolism of amino
acids.
33. 2. Changes to a new framework on carbon of
amino acids molecules.
The picture shows the carbon chains of amino acid metabolism associated
with the citric acid cycle
34. The Formation Of Acetyl Coenzyme A
In Figure looks that Acetyl
Coenzyme A is connector
compounds between the
amino acid metabolism and
the citric acid cycle.
There are two metabolic
pathways that lead to the
formation of Acetyl Coenzyme
A, i.e.
-through the pyruvic acid and
-through acetoacetate acid
35. Amino acids that undergoes metabolic pathways through the
pyruvic acid is alanin, cysteine, glycine, serine, and threonine.
Alanin produces pyruvic acid by direct
reaction with transaminasi α
ketoglutarate.
Serin undergoes dehydration and
deamination by the enzyme of serine α
dehidratase.
Threonine is converted to glycine and
asetaldehid by the enzyme of threonine
aldolase.
Glycine is then converted into Acetyl Coenzyme A via the serine formation with
the addition of one atom of carbon, such as methyl hydroxyl and formyl.
Coenzyme that works here is tetrahidrofolat.
37. Alanine
Transamination process:
These reaction is reversible
Pyruvic acid is a compound that is formed on the carbohydrate
metabolism. Thus the metabolic reaction alanin is the relationship
between metabolism of proteins with carbohydrate metabolism
38. Valin
Through a few stages of the reaction, valin can be converted
into suksinil KoA which then enter into the citric acid cycle
isobutril KoA
suksinil KoA
41. Reaction 1. Synthesis of Karbamil Phosphate
In reaction to the formation of karbamil phosphate, one mole
of ammonia reacts with one mole of carbon dioxide with the
help of the enzyme karbamilfosfat synthetases. This reaction
requires energy, so this reaction involves two moles of ATP is
converted into ADP
In addition as a cofactor required Mg ++ and N-acetyl-
glutamate.
42. Reaction 2. The formation of sitrulin
Karbamil phosphate formed reacts with ornitin to form
sitrulin. In this reaction the karbamil join ornitin and separate
the phosphate groups. As a catalyst to the formation of sitrulin
is ornitin transkarbamilase found in the mitochondria of liver
cells.
43. Reaction 3. The formation of arginosuksinate acid.
Sitrulin reacts with aspartic acid forming argininosuksinat acid.
This reaction takes place with the help of the enzyme
argininosuksinat synthetases.
In the reaction of ATP is a source of energy by way of releasing
the phosphate group and turned into AMP
44. Reaction 4. Decomposition of Argininosuksinat acid.
Argininosuksinat acid in this reaction is outlined to be arginine and
fumaric acid. This reaction takes place with the help of the enzyme
argininosuksinase, an enzyme in the liver and kidneys.
45. Reaction 5. Decipherment of arginine
This last reaction phase complete reaction of the urea cycle. In
this reaction the arginine outlined being urea and ornitin. An
enzyme that works as a catalyst in the reaction of this
decomposition is arginase in liver.
Ornitin formed in the reaction of this hydrolysis react again with
karbamilphosphete to form sitrulin (In reaction 2)
This reaction take place repeatedly form a cycle. As for urea removed from the
body through the urine.
46. The overall reaction of Urea cycle is as follows:
Chemical process in urea cycle
occurs in the liver because of
the enzymes work as catalysts
are primarily found in the
mitochondria of liver cells
47. Biosynthesis of Protein
In the process of protein biosynthesis, DNA molecule serves
as a mold for the formation of RNA, and RNA molecule then
directs the sequence of amino acids in the formation of
protein molecules, which occurs in Ribosomes.
Thus the flow of genetic information in cells is as follows:
48. DNA (Deoxyribo Nucleic Acid)
The DNA molecule is a chain of polinukleotida which has some
kind of purin base and primidin, and the form is double helix.
Among one chains with the
partner in the double helix there
are hydrogen bonds, i.e. bonds
that occurs between adenine with
thymine (A-T) and between
guanine and cytosine (G-C)
In the process of protein biosynthesis, DNA
molecule serves as a mold for the formation of
RNA
50. Kinds of RNA
1. rRNA (ribosomal RNA) together with proteins are
components that form Ribosomes in the cell.
even though it is the main component of the rRNA
Ribosome, however his role in protein synthesis takes
place in the Ribosomes is not yet known
2. mRNA (massanger RNA)
3. tRNA (transfer RNA)
51. 2. mRNA (massanger RNA) is produced within the cell nucleus
and RNA is the least amount, i.e. approximately 5% of all RNA
within the cell.
formation of mRNA in the cell nucleus uses a DNA molecule as a
molecule of mold and order of bases on the mRNA complement
is one of a chain of DNA molecules.
Thus the sequence of bases purin
and primidin one of the chains of
the DNA molecule, where the base
thymine (T) is replaced by uracil
(U).
mRNA that has been formed in the
cell nucleus and then out of the
cell nucleus and into the cytoplasm
and are bound to Ribosomes
52. 3. tRNA (Transfer RNA)
The primary function of tRNA is to bring the amino acid in
translation process of mRNA codon into a sequence of amino
acids that form a protein
1. Stem of the amino acids.
2. The stem and loop UH2 or
dihydro uridin
3. Stem and loop of antikodon
4. Extra Stem
5. Stem and loop the U or
pseudoridin.
54. Two Process in the synthesis of proteins is:
1. Transcription
transcription is the formation of RNA molecules
according to the messages given by DNA. At this
stage of genetic information was given to the
RNA molecule that is formed as an intermediate
in the synthesis of proteins
2. Translation
NA molecules translate genetic information into
protein formation process