Amino Acids
Writer’s view
about Amino Acid.
Consider a universe. In which there are a number of
planets. In these planets consider the earth. In the earth are many countries
and in countries are cities and in cities are many buildings. When we consider a
single building we come to know that it is made up of many bricks that are the
basic building block.
Now let us imply this to human body. Our body is composed of many chemical substances. But we are only interested in proteins.
Proteins consist of many protein fibers that are “the countries of earth”. The protein fibers in turn consist of many polypeptide chains. A single polypeptide is made of groups of building blocks. When a group of those building blocks is examined it is revealed that each of them has a basic unit that is the AMINO ACID. Amino acid is the” brick”, basic structural entity for proteins.
Importance of
amino acids.
Amino
acids help in performing the very vital functions of body like carrying oxygen (as
hemoglobin), protecting the body (as antibodies) etc.
Occurrence and introduction.
Up till
now about 500 amino acids have been found out of which 170 are present in body
cells.
But only
20-26 are required by humans. Out of those 20 amino acids, 10 are prepared by
the body itself but called non-essential amino acids (Ghar ki murghii daal
brabar XD).
Our body
requires the ones which are not synthesized by it, hence essential amino acids
and as the name says it all “essential”, without them body can face many
diseases.
Structure.
These
belong to the organic class of compounds with a central carbon atom to which is
attached a ----COOH (carboxyl
group), a ----NH2 (amino group) , a hydrogen atom and a
R-group. This R may be any maaja gaama from the organic family or hydrogen in a
single case this would be explained later in the topic.
For the
time being let’s understand the concept of
acidic and basic amino acids.
This
depends upon the two main functional groups attached to the carbon i.e. the
amino group and carboxyl group.
When two NH2---- groups are
attached to the central carbon atom then it is called basic amino acid.
When two COOH----groups are attached to the
central carbon atom then it is called acidic
amino acid.
*Reason*
Amino group resembles ammonium which is a base, two such
groups increase the pKa value and nitrogen tends to accept proton, making it a
base.
Similarly carboxyl
groups resemble carboxylic acids, which are acidic in nature. This lowers the
pKa value and proton is removed.
Zwitter ion:
Now when a
neutral amino acid is subjected to a
system of varied pH , certain changes occur in them.
FOR EXAMPLE:-
When a
neutral amino acid is subjected to a system having lower pKa value the proton
from amino group is transferred to the carboxyl group of the same amino acid
i.e. within the same molecule. This gives a positive charge to the amino group and
a negative charge on carboxyl group. On the whole there is no net electrical charge on the molecule. This is called zwitter ion or internal salt.
NOTE: on
the basis of position of amino group attached to the central/alpha carbon we
can name the amino acids as α-β-γ amino acids.
Entry # 9
By Ahmad Azeem
0 comments:
Post a Comment