Question

single letter abbreviation of all amino acids that correspond

4. Amino acids. The side chains of amino acids have a wide spectrum of chemical and physical properties. In each sp. provided below, write the single-letter abbreviations of all amino acids that match the description positively charged side chains at pH 7.4 negatively charged side chains at pH 7.4 negatively charged side chains at pH 12 achiral contains two chiral carbons side chain restricts the rotation of main chain contains carboxamide side chains often found in the active site of enzymes, where it can serve as either acid or base catalyst least soluble in water (Hint: see Table 12.2 in textbook.) most soluble in water contains hydroxyl groups N-terminal amino acid residue of proteins often found in B-turns, rarely found in a-helices can form disulfide crosslinks under oxidizing conditions, especially in extracellular proteins attachment sites of sugars in glycoproteins (Hint: see Chapter 11 in textbook.]

Answer 1

1. R, K and H are positively charged side chains at pH 7.4

Arginine, Lysine and Histidine are positively charged amino acids with side chains containing nitrogen. They bind protons and gain positive charge.

2. D and E are negatively charged side chains at pH 7.4

Aspartic acid (D) and Glutamic acid (E) are negtaively charged aminoacids with acidic side chains.

3. Y( Tyrosine), C( Cysteine), D(Aspartic acid) and Glutamic acid( E) are negatively charged at pH 12.

4. G( Glycine) is achiral.

All aminoacid except glycine are chiral. Glycine is achiral because it doesnot contain bulky side chain.

5. Isoleucine (I) and Threonine (T) contain two chiral centres.

They are the aminoacids which have two asymmetric carbon ie.,carbon with four different groups attached to it.

6. P(Proline) side chain restrict the rotation around main chain.

Poline is  an imino-acid with a five-member ring which sterically restrict rotation around the N-C(alpha) bond.

7. N ( Asparagine) and Q (Glutamine) contain carboxamide side chains.

8. H ( Histidine) is often found in active site of enzyme and act as general acid or base catalyst.

9. F( Phenylalanine) is least soluble in water.

10. Serine( S), Threonine(T), Cysteine(C) , Asparagine(N) and Glutamine( Q) are most soluble in water as they are polar.

11. S(Serine), T(Threonine) and Y( Tyrosine) contain hydroxyl group.

12. M(Methionine) forms the N-terminal amino acid residue of protein

13. P ( Proline) and G( Glycine ) are often found in beta turns.

14. C( Cysteine) can form disulfide bonds.

Thiol group of cysteine residues form disulfide bonds by process of oxidation.

15. N(Asparagine), S( Serine) and T(Threonine) are the attachment sites of sugars in glycoproteins.

In glycoproteins, sugars are attached either to the amide nitrogen atom in the side chain of asparagine known as an N-linkage or to the oxygen atom in the side chain of serine or threonine known as an O-linkage.