Unformatted text preview: 20.  Name an amino acid among the repertoire of 20 amino acids found in proteins that can absorb
light with a wavelength of 280 nm. Lt Wm$IM 21.  Which amino acid from the set of 20 has a cyclic structure in which its side chain is covalently
bonded to both the amino group and the a carbon atom? Lt @mww. 22.  Draw the complete chemical structure of histidine (His). Make sure that your structure shows
the major ionic species present in an aqueous solution at pH 4.5. O
@Ham» C ’ C(@
o 23.  Examine the sequence of the ﬁve peptides shown below and answer the following questions
about their properties using the numbers assigned to each peptide: 1aALg=Lys-Met 2- Gly-Asn-Arg ‘S-Aep-ﬁp-Ala 4—Asp—Gl-n—Ala—Gflu ﬁrteu-VaisAla A. Which e tidep: most posrtlvel char dat pH 7? AQ' 1\
77 B. Which peptidea ha m'no aci with an a omatic side chain? are 969—61" 0t C. Which peptide contains the argest number of nonpolar R groups? 4‘5 LUJI \lmv Mar D. Which peptide contains sulfur?
4* I: M03 Lxls met
24. }xplain why the peptide bond' Is planar?
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’V mien WI OIA 0W%lef$ OP 0: "a W. \l’ =1 +85 , i f -5-
Fort/mi aouble bond characlcec- /O ...
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- Fall '10