Answer the following eight questions (a through h) based upon a tripeptide seque
ID: 779636 • Letter: A
Question
Answer the following eight questions (a through h) based upon a tripeptide sequence of the following amino acids (one-letter codes are given): Q A D
a) What is the full name of each of the three amino acids? Spelling counts, but capitalization does not. If one of the answers is an acidic amino acid, use the %u2013ate ending instead of the %u2013ic acid ending.
b) What is the three-letter code for each of the amino acids?
c) What is the overall charge on the tripeptide at physiological pH (pH 7.4)?
d) For each of the amino acids, is the side chain (R group) hydrophobic, polar but uncharged, positively ( ) charged, or negatively (%u2013) charged at physiological pH?
e) What is the overall charge of the tripeptide below pH 1.0?
f) What is the overall charge of the tripeptide at pH 12?
g) What type of intermolecular attractions could the side chains of the amino acids make with the solvent (water) at pH 7.4? (Note that these are attractions with water, not with other amino acids.)
h) If the tripeptide was dissolved in a buffer that is pH 8.5, what would be the net charge on the most abundant chemical species?
Explanation / Answer
One letter code Three letter code Amino acid Possible codons A Ala Alanine GCA, GCC, GCG, GCT B Asx Asparagine or Aspartic acid AAC, AAT, GAC, GAT C Cys Cysteine TGC, TGT D Asp Aspartic acid GAC, GAT E Glu Glutamic acid GAA, GAG F Phe Phenylalanine TTC, TTT G Gly Glycine GGA, GGC, GGG, GGT H His Histidine CAC, CAT I Ile Isoleucine ATA, ATC, ATT K Lys Lysine AAA, AAG L Leu Leucine CTA, CTC, CTG, CTT, TTA, TTG M Met Methionine ATG N Asn Asparagine AAC, AAT P Pro Proline CCA, CCC, CCG, CCT Q Gln Glutamine CAA, CAG R Arg Arginine AGA, AGG, CGA, CGC, CGG, CGT S Ser Serine AGC, AGT, TCA, TCC, TCG, TCT T Thr Threonine ACA, ACC, ACG, ACT V Val Valine GTA, GTC, GTG, GTT W Trp Tryptophan TGG X X any codon NNN Y Tyr Tyrosine TAC, TAT Z Glx Glutamine or Glutamic acid CAA, CAG, GAA, GAG * * stop codon TAA, TAG, TGA