THIS CHAPTER IN CONTEXT
Most of an organism’s genetic information directs the synthesis of proteins,
which are the molecules that carry out virtually all the metabolic work of the
organism. In this chapter, we take a close look at the oxygen-binding proteins
myoglobin and hemoglobin. Myoglobin is an intracellular protein that gives vertebrate
muscles their red color, and hemoglobin is the major protein of red blood cells.
These two proteins provide a wealth of information on how molecular structure
is related to biological function. The chapter first looks at the chemical properties
of the amino acid components of proteins, along with methods for determining the
sequence of amino acids in a protein. Next comes a discussion of how the protein
backbone and side chains fold into a unique three-dimensional shape stabilized
by noncovalent forces. Detailed structural information about proteins such as
myoglobin and hemoglobin leads to an understanding of how these proteins bind
oxygen and how their physiological function is modulated by other factors. A comparison
of the molecular structures of these protein also sheds light on how proteins
evolve.
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