Problem 1
Translate the following amino acid sequence into one-letter code: Glu-Leu-Val- Ile-Ser-Ile-SerLeu-Ile-Val-Ile-Asn-Gly-Ile-Asn-Leu-Ala-Ser-Val-Glu-GlyAla-Ser.
Problem 2
Pyrrolysine (Pyl, O) and selenocysteine (Sec, U) are two uncommon amino acids. Knowing that these amino acids exist, translate the following amino acid sequence into one-letter code: Thr-Trp-Ile-Thr-CysHis-Tyr-Leu-Ile-Thr-Thr-Ile- Glu-Phe-Glu-Arg-Arg-GluThr-Ala-Arg-Glu-Asn-Thr-Tyr-Pyl-Sec-Met-Ala-LeuPhe-Pyl- Tyr.
Problem 5
Match each amino acid in the left-hand column with the appropriate side-chain type in the right-hand column. \(\sqrt{1}\). (a) Leu____________________ (b) Glu__________________ (c) Lys_____________ (d) Ser_________________ (e) Cys_____________ (f) Trp________________ 1\. hydroxyl-containing 2 . acidic 3\. basic 4\. sulfur-containing 5 . nonpolar aromatic 6 .nonpolar aliphatic
Problem 6
In each of the following pairs of amino acids, identify which amino acid would be most soluble in water: (a) Ala, Leu; (b) Tyr, Phe; \((c)\) Ser, Ala; (d) Trp, His.
Problem 7
What is the net charge on the amino acid glycine at \(\mathrm{pH}\) 7? At pH \(12 ?\)
Problem 8
The isoelectric point (pI) is the pH at which a molecule has no net charge. The amino acid glycine has two ionizable groups: (1) a carboxylic acid group with a \(\mathrm{p} K_{\mathrm{a}}\) of 2.72 and (2) an amino group with a \(\mathrm{p} K_{\mathrm{a}}\) of \(9.60 .\) Calculate the pI of glycine.
Problem 9
Which amino acids have positively charged \(R\) groups at \(\mathrm{pH} 7 ?\)
Problem 10
Differentiate between a nonessential and an essential amino acid.
Problem 11
What three amino acids have aromatic components in their side chains? \(\sqrt{1}\).
Problem 12
Which amino acid side chains are capable of ionization?
