Effect of heat on amino acids
α-Amino acids on heating → diketopiperazine
β-Amino acids on heating → α,β-unsaturated acids
γ-Amino acids on heating → lactam
δ-Amino acids on heating → lactam
(α-Amino acids on heating give diketopiperazine (cyclic diamide

β-Amino acids on heating give α,β-unsaturated acids

(γ-Amino acids on heating give lactam (five-membered cyclic ester

(δ-Amino acids on heating give lactam (six-membered cyclic ester
