Question

................ and, ............... are present at the N and C terminal of the β-chain of threonine

A) Phenylalanine and alanine

B) Glycine and asparagine

C) Leucine and isoleucine

D) Methionine and tryptophan

Answer 1

Hint:Threonine (symbol Thr or T) is an amino acid that is used in the biosynthesis of proteins. It comprises an α-amino group (which is in the protonated −NH
3 form underneath organic conditions), a carboxyl crew (which is in the deprotonated −COO− structure beneath organic conditions), and an aspect chain containing a hydroxyl group, making it a polar, uncharged amino acid.

Complete- Step-by Step-Answer:

A peptide is a chain of amino acids in which the α-amino of one amino acid is bonded to the α-carboxyl team of the next. Thus, every bond linking the amino acids is a secondary amide, referred to as a peptide bond. If a peptide made from two amino acids is a dipeptide, one made from three is a tripeptide, and so forth.
 As we have viewed many times, the prefixes, di-, tri-, tetra-, etc., point out the range of amino acid devices from which the chain is made. Peptides that include completely a few amino acids— up to about fifty— are referred to as oligopeptides; peptides with greater than 50 amino acids are called polypeptides, a period synonymous with protein.

A peptide has two ends: the end with a free amino team is referred to as the N-terminal amino acid residue. The end with a free carboxyl team is referred to as the C-terminal amino acid residue. Peptides are named from the N-terminal acid residue to the C-terminal amino acid.


Hence, the correct option is (A ) Phenylalanine and alanine.

Note: Phenylalanine, an essential amino acid, is a derivative of alanine with a phenyl substituent on the β carbon. Phenylalanine is quite hydrophobic and even the free amino acid is not very soluble in water.