1. Figure: 22.1
Title:
Table Examples of the many functions of proteins in biological systems.
Caption:
The functions of proteins are described.

2. Figure: UN
Title:
D-Glyceraldehyde and L-glyceraldehyde.
Caption:
Naturally occurring monosaccharides have the D-configuration. Naturally occurring amino acids have the L-configuration.

5. Figure: UN
Title:
Structures of amino acids at different pH values.
Caption:
At a low pH value, the amino group and the carboxyl group are protonated. At a high pH value, the amino group is not protonated and the carboxyl group has lost a proton.

6. Figure: UN
Title:
Histidine at different pH values.
Caption:
The structure of histidine depends upon the pH value.

7. Figure: UN
Title:
Tripeptides.
Caption:
A tripeptide is formed from three amino acids.

8. Figure: UN
Title:
Resonance contributors in a peptide bond.
Caption:
The trans configuration is more stable.

9. Figure: UN
Title:
A thiol is oxidized to a disulfide.
Caption:
A common oxidizing agent is bromine or iodine in a basic solution.

10. Figure: UN
Title:
Mechanism for the oxidation of a thiol to a disulfide.
Caption:
The acidic hydrogen is removed by base. The nucleophilic sulfur attacks bromine. Another sulfide group attacks the sulfur, expelling the bromide. A disulfide is formed.

11. Figure: UN
Title:
A disulfide can be reduced to a thiol.
Caption:
The number of S-H bonds increases in a reduction reaction.

12. Figure: UN
Title:
Cysteine is oxidized to cystine.
Caption:
A disulfide bridge is formed.

13. Figure: 22.6
Title:
Figure A segment of a polypeptide chain.
Caption:
Colored squares indicate the plane defined by each peptide bond.

14. Figure: 22.7
Title:
Figure Disulfide bridges cross-linking portions of a peptide.
Caption:
Disulfide bridges contribute to the overall shape of the protein.

15. Figure: UN
Title:
Intrachain and interchain disulfide bridges.
Caption:
Intrachain disulfide bridges bond together different parts of the same polypeptide molecule. Interchain disulfide bridges bond together different polypeptide molecules.

16. Figure: UN
Title:
Bradykinin, vasopressin, and oxytocin.
Caption:
Bradykinin, vasopressin, and oxytocin are peptide hormones.

17. Figure: UN
Title:
Aspartame.
Caption:
Aspartame is Nutrasweet. Aspartame is the methyl ester of a dipeptide of L-aspartate and L-phenylalanine.

18. Figure: UN
Title:
Combinations of glycine and alanine.
Caption:
Four possible dipeptides can be formed from glycine and alanine.

19. Figure: UN
Title:
Secondary structure of proteins.
Caption:
Secondary structure includes hydrogen bonding between peptide bonds.

20. Figure: 22.8a
Title:
Figure 22.8a. A segment of a protein in an a-helix.
Caption:
Each hydrogen attached to an amide nitrogen is hydrogen bonded to a carbonyl oxygen of an amino acid four amino acids away.

21. Figure: 22.8b
Title:
Figure 22.8b. The helix is stabilized by hydrogen bonding between the peptide groups.
Caption:
Each hydrogen attached to an amide nitrogen is hydrogen bonded to a carbonyl oxygen of an amino acid four amino acids away.

22. Figure: 22.8c
Title:
Figure 22.8c. Looking at the longitudinal axis of an -helix.
Caption:
Each hydrogen attached to an amide nitrogen is hydrogen bonded to a carbonyl oxygen of an amino acid four amino acids away.

23. Figure: 22.9
Title:
Figure Segments of b-pleated sheets drawn to illustrate their pleated character.
Caption:
Note that the first is parallel and the second is antiparallel.

24. Figure: 22.10
Title:
Figure The backbone secondary structure of carboxypeptidase A.
Caption:
a-Helical sections are purple. b-Sheet sections are indicated by flat green arrows pointing toward the carboxy terminus of the protein.

25. Figure: 22.11
Title:
Figure Three-dimensional structure of carboxypeptidase A.
Caption:
The tertiary structure of a protein is the three-dimensional arrangement of all the atoms in the protein.

26. Figure: 22.12
Title:
Figure Stabilizing interactions involved in maintaining the tertiary structure of a protein.
Caption:
Tertiary structure is maintained by interactions between side chains of different amino acids within the same protein molecule.

27. Figure: UN
Title:
Possible quaternary structure for a hexamer.
Caption:
The quaternary structure describes the way the subunits are arranged in space.

28. Figure: 22.13
Title:
Figure A representation of the quaternary structure of hemoglobin generated by computer graphics.
Caption:
The orange and green represent the polypeptide chains.