amino acids are converted to succinyl – CoA, except Histidine

039. All of the following amino acids are converted to succinyl – CoA, except:

1. Methionine

2. Isoleucine

3. Valine

4. Histidine

Answer

4. Histidine

Reference:

Harper 26^th Edition Pages 249, 262

Lippincott 3^rd Edition Page 261 to 263

Chaterjee 6^th Edition Page 457

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Discussion

Amino acids that forms Succinyl CoA are

1. Methionine through Propionyl CoA

2. Valine through L-Methyl Malonyl CoA

3. Isoleucine through Propionyl CoA

4. Threonine through Propionyl CoA (Threonine undergoes non oxidative deamination to become Propionyl CoA)

Propionyl CoA is converted to Succinyl CoA. Other sources of Propionyl CoA are

1. Beta oxidation of odd chain fatty acids

2. Oxidative decarboxylation of alpha keto glutarate

3. Activation of Succinic Acid

Explanation

Histidine metabolism yield

1. Urocanic acid

2. 4-imidazolone-5-propionate

3. Formiminoglutamic acid (Fliglu)

4. Glutamate

Comments

Histidine also forms

1. Ergothioneine

2. Carnosine

3. Anserine

Tips

Carnosine is a dipeptide of histidine with beta-alanine (b-alanyl histidine). It is present in skeletal muscle