Answer- Case study- Epilepsy

Question of the day

A 12-year-old boy develops convulsions. After running an electroencephalogram (EEG), a neurologist determines that the child has epilepsy. He is started on Benzodiazepine, which promotes the activity of GABA. GABA is derived from the amino acid glutamate via which of the following biochemical reactions?

A. Deamination

B. Decarboxylation

C. Hydroxylation

D. Iodination

E. Methylation

Answer- The correct answer is B- Decarboxylation, Glutamic acid undergoes decarboxylation to yield GABA. The reaction is catalyzed by Glutamic acid decarboxylase that requires vitamin B6-P as a coenzyme. GABA is an inhibitory neurotransmitter and is thus helpful in controlling convulsions.

Deamination is the process of removal of amino group of amino acid as ammonia. Removal of amino group is a prerequisite for the catabolism of amino acids. Ammonia thus released is converted to urea and the carbon skeleton is used for the conversion to glucose, ketone bodies or energy.

Hydroxylation is carried out by mono oxygenases, e.g. Hydroxylation of phenyl alanine produces tyrosine. The reaction is catalyzed by phenyl alanine hydroxylase enzyme. Similarly hydroxylation of tyrosine yields DOPA (dihydroxy phenyl alanine).

Iodination is the process of incorporation of iodine into the substrate. The synthesis of thyroid hormone requires iodination of tyrosine.

Methylation is mostly carried out by S-Adenosyl Methionine, which is an important methyl group donor in the body. A number of biologically important compounds are synthesized by methylation reactions. To name a few, e.g.the conversion of nor epinephrine to epinephrine; guanido acetic acid to methyl guanido acetic acid (creatine); uracil to thymine and N-acetyl serotonin to melatonin etc.

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