Explain the Metabolism of amino acids in a human body

When energy intake is adequate, the amino acids derived from the dietary protein are
used first for synthesizing body proteins. Those amino acids in excess of needs for
growth and maintenance lose their characteristic NH2 group and enter the same
metabolic pathways as carbohydrates and lipids, to be used as sources of energy. First
the amino acids are deaminated (lose their nitrogen) and then they are catabolized in a
variety of ways.

Deamination
This is the process of removing the nitrogen containing amino groups from an amino
acid. Two products result from deamination, one is the structure without its amino
group and is usually a keto acid. The other product is ammonia, a toxic compound
which is released in the blood stream to the liver where it is converted to urea a (less
toxic compound) and returned into the blood. The kidney then filters the urea out of
the blood.

Glucogenic amino acids
These are amino acids capable of producing glucose and include alanine, serine,
glycine, cycteine, methionine and tryptophan. Other amino acids including
phenylalanine, tyrosine, leucine, isoleucine and lycine can be broken down like fat
into two 2-carbon fragments that eventually form acetyl coenzyme (CoA). These
amino acids like fat are capable of forming compounds called ketones, which can be
used as a source of energy. They are therefore known as ketogenic amino acids.

Synthesis of nonessential amino acids
Only some amino acids are essential and are obtained from the diet. Others can be
made in the body, given a source of nitrogen; these are the non-essential amino
acids. The body does this by transferring an amino group from one amino acid to its
corresponding keto acid, producing a new amino acid and a new keto acid through the
process called transamination. Through many such reactions involving many keto
acids, the liver cells can synthesize the non-essential amino acids.

Using amino acids for energy
Needs for energy and for glucose has priority than an amino acid to build a vital
protein. Without energy cells die: without glucose brain and nervous systems falter.
Cells are forced to use amino acids for glucose and energy when concentrations of
glucose and fatty acids are low. Body proteins are broken down to meet energy and
glucose needs. This can lead to muscle wasting. One must therefore take a diet
adequate in carbohydrates and fats to spare amino acids from being used for energy.

Amino acids to fats.
The body cannot store surplus amino acids. If a person eats excess protein, the amino
acids are deaminated, their nitrogen excreted and the remaining carbon fragments are
converted to fat and stored for later use. In this way proteins can contribute to
obesity.

Protein turn over
Refers to the degradation and synthesis of endogenous protein. When proteins break
down, they free amino acids to join the general circulation. Some of these amino
acids may be promptly recycled into other proteins, others may be stripped of their
nitrogen and used for energy. Together the constant synthesis and degradation of
body proteins are known as protein turn over. The protein that participates in these
function are endogenous protein (protein in body).

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Titany answered the question on November 5, 2021 at 09:34