KCET2026ChemistryBiomolecules
Incorrect statement about -amino acids of proteins among the following is
Options
- AMethionine is an essential amino acid
- BGlycine doesn't exhibit enantiomerism
- CGlycylalanylglycine has three amide linkages
- DZwitterion of valine exhibits amphoteric behaviour
Correct answer
C. Glycylalanylglycine has three amide linkages
Step-by-step solution
Methionine is an essential amino acid, so the first statement is correct. Glycine is the simplest amino acid with the formula H₂N-CH₂-COOH . Since its -carbon is attached to two identical hydrogen atoms, it is achiral and does not exhibit enantiomerism. Thus, the second statement is correct. Glycylalanylglycine is a tripeptide formed by the condensation of three amino acids (glycine, alanine, and glycine). The number of peptide (amide) linkages in a peptide is equal to the number of amino acid residues minus one. T