in this lecture we will start talking about the metabolism of amino acids.
The structure of amino acids
A carbon compound that has a central carbon atom called the carbon and this
carbon is connected to 4 different groups which are :
1- Carboxyl group
2- Amino group
3- Hydrogen atom
4- “ R ” group, which differs between amino acids
In protein structures we have only 20 amino acids, but there
are other amino acids in our body that do functions other than
protein synthesis.
The 20 amino acids are present in our body in 2 conformations : D&L ( as an
enantiomers ).
L : is the conformation present in proteins structures
Note : our cells can deal with D amino acids via a certain pathway we will get to it
in later lectures
Peptides are made by the interaction of the carboxyl group of the first amino acid
with the amino group of the second amino acid which forms a peptide bond and
the free sides make up the C & N terminuses.
, Amino Acid Pool
Amino acids can’t be stored in cell ( unlike sugars which can be stored as
glycogen) so we have a fixed amount of amino acids in our body that is called “
Amino Acids pool ” which makes up about 90-100 grams in our
body, this pool can be supplied but also constantly consumed
by different pathways so there is an “ in &out ” movement to
maintain this pool.
Amino acids are an important source of nitrogen, and this
nitrogen is released as ammonia (NH3) which is a very toxic
compound that may affect the CNS if it reaches toxicity
concentrations in the blood, so we need to maintain a balance
of amino acids.
Although almost 60% of our body is made up from water, but it
can’t dilute NH3 to reach non-toxic concentrations ( we will
discuss the elimination of NH3 in future lectures ).
Sources of amino acids :
1- Exogenous: proteins / Amino Acids form Diet
2- Endogenous: protein degradation which is constantly
taking place to eliminate misfolded, non-functional
proteins or a protein that has finished its function.
3- Non-essential amino acids synthesized from metabolic
pathway.
Amino acids depletion routes:
1- Synthesis of proteins
2- Amino acids consumed as precursors of nitrogen
containing small molecules ( ex : heme groups,
hormones, etc. )
3- Conversion of Amino Acids to α-keto acids, glucose,
glycogen, fatty acids, ketone bodies, or CO2 + H2O.
The structure of amino acids
A carbon compound that has a central carbon atom called the carbon and this
carbon is connected to 4 different groups which are :
1- Carboxyl group
2- Amino group
3- Hydrogen atom
4- “ R ” group, which differs between amino acids
In protein structures we have only 20 amino acids, but there
are other amino acids in our body that do functions other than
protein synthesis.
The 20 amino acids are present in our body in 2 conformations : D&L ( as an
enantiomers ).
L : is the conformation present in proteins structures
Note : our cells can deal with D amino acids via a certain pathway we will get to it
in later lectures
Peptides are made by the interaction of the carboxyl group of the first amino acid
with the amino group of the second amino acid which forms a peptide bond and
the free sides make up the C & N terminuses.
, Amino Acid Pool
Amino acids can’t be stored in cell ( unlike sugars which can be stored as
glycogen) so we have a fixed amount of amino acids in our body that is called “
Amino Acids pool ” which makes up about 90-100 grams in our
body, this pool can be supplied but also constantly consumed
by different pathways so there is an “ in &out ” movement to
maintain this pool.
Amino acids are an important source of nitrogen, and this
nitrogen is released as ammonia (NH3) which is a very toxic
compound that may affect the CNS if it reaches toxicity
concentrations in the blood, so we need to maintain a balance
of amino acids.
Although almost 60% of our body is made up from water, but it
can’t dilute NH3 to reach non-toxic concentrations ( we will
discuss the elimination of NH3 in future lectures ).
Sources of amino acids :
1- Exogenous: proteins / Amino Acids form Diet
2- Endogenous: protein degradation which is constantly
taking place to eliminate misfolded, non-functional
proteins or a protein that has finished its function.
3- Non-essential amino acids synthesized from metabolic
pathway.
Amino acids depletion routes:
1- Synthesis of proteins
2- Amino acids consumed as precursors of nitrogen
containing small molecules ( ex : heme groups,
hormones, etc. )
3- Conversion of Amino Acids to α-keto acids, glucose,
glycogen, fatty acids, ketone bodies, or CO2 + H2O.
