<prompt> FIGLU is intermediate product of metabolism ofHistidineGlutamineAlanineTryptophan  <response>: Ans. a Histidine Ref. Harpers Biochemistry 28thpg. 16. Figlu or N-formimino glutamate - is formed during catabolism of Histidine. During process, transfer of the formimino group of Figlu to tetrahydrofolate H4 folate forms glutamine. In folic acid deficiency, this reaction is partially or totally blocked and figlu is excreted in the urine. Excretion of Figlu following a test dose of Histidine therefore provides a diagnostic test for folic acid deficiency. Figlu test and Histidine test: Formimino-glutamate figlu, a catabolite of Histidine, transfers its formimino group to H4- folate to form N5 formimino-H4 folate.In folate deficiency, Figlu will accumulate after oral challenges with Histidine.Histidine: maximum buffering capacity- Maximum pH regulation seen has no charge at neutral pH- proteinate and deproteinate at neutral pH In folic acid deficiency, group transfer to THF is impaired and Figlu is excreted. 