4. The melanocyte-stimulating peptide hormone a- melanotropin has the following sequence:
Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val
a. Write the sequence using the one-letter abbreviations.
b. Calculate the molecular weight of a -melanotropin, using data in Table 5.1.
In Table 5.1

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TABLE 5.1 Name Properties of the common amino acids found in proteins pKa of lonizing Residue Mass Occurrence Side Chain Abbreviations 1- and 3-letter codes aCOOH Group A, Ala R, Arg N, Asn pKa of pKa of -NH3 Group (daltons) in Proteins (mol %) 9.7 Alanine Arginine Asparagine Aspartic acid D, Asp Cysteine Glutamine Glutamic acid E, Glu Glycine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine F, Phe Proline Serine Threonine Tryptophan yrosine Valine 71.08 156.20 114.11 115.09 103.14 128.14 129.12 57.06 137.15 113.17 113.17 128.18 131.21 147.18 97.12 87.08 101.11 186.21 163.18 99.14 2.3 2.2 12.5 8.8 9.8 10.8 5.0 4.2 5.9 1.3 3.7 3.9 8.3 C, Cys O, Gln 2.2 2.2 2.3 9.7 9.6 9.2 9.7 9.6 9.0 9.2 4.2 G, Gly 7.9 2.4 5.5 IS 2.4 L, Leu K, Lys M, Met 2.2 10.0 2.0 4.0 P Pro S, Ser T, Thr W, Trp Y, Tyr V Val 10.6 9.2 10.4 9.4 5.6 2.4 1.5 10.1