Antihistaminics

Antihistaminics – drugs which antagonize the effects of histamine.

6 Branched-chain amino acids
Valine,Leucine and Isoleucine
are all essential, their final metabolites are different:
valine is glucogenic,
leucine is ketogenic,
isoleucine both gluco- and ketogenic.
These amino acids are taken up from the blood predominantly by skeletal muscles and their catabolism (transamination) begins there.
The three initial catabolic reactions are common to all three
branched-chain amino acids:
– transamination to corresponding 2-oxoacids,
– oxidative decarboxylation catalyzed by 2-oxoacid dehydrogenase producing corresponding acyl-CoA thioesters, and
– the second dehydrogenation between carbons ? and ? catalyzed by flavin dehydrogenase resulting in corresponding 2-alkenoyl-CoA thioesters:
The resulting 2-alkenoyl-CoAs after three initial reactions:

The following reactions differ (expected addition of water, hydration, occurs as the next reaction only in the case of valine and isoleucine).