C

Protein A Protein C Less stable complex

Protein A Protein B Stable complex

Protein A Protein C Less stable complex

▲ FIGURE 2-10 Molecular complementarity and the binding of proteins via multiple noncovalent interactions. The complementary shapes, charges, polarity, and hydrophobicity of two protein surfaces permit multiple weak interactions, which in combination produce a strong interaction and tight binding. Because deviations from molecular complementarity substantially weaken binding, any given biomolecule usually can bind tightly to only one or a very limited number of other molecules. The complementarity of the two protein molecules on the left permits them to bind much more tightly than the two noncomplementary proteins on the right.

Depending on the number and strength of the noncova-lent interactions between the two molecules and on their environment, their binding may be tight (strong) or loose (weak) and, as a consequence, either long-lasting or transient. The higher the affinity of two molecules for each other, the better the molecular "fit" between them, the more non-covalent interactions can form, and the tighter they can bind together. An important quantitative measure of affinity is the binding dissociation constant Kd, described later.

As we discuss in Chapter 3, nearly all the chemical reactions that occur in cells also depend on the binding properties of enzymes. These proteins not only speed up reactions but also do so with a high degree of specificity, a reflection of their ability to bind tightly to only one or a few related molecules. Indeed, the binding specificity of large biological molecules, particularly proteins and nucleic acids, is one of the distinctive features that distinguish biochemistry from typical solution chemistry. Clearly, molecular complementarity and noncovalent interactions underlie the structures of bio-molecules and many processes critical to life.

10 Ways To Fight Off Cancer

10 Ways To Fight Off Cancer

Learning About 10 Ways Fight Off Cancer Can Have Amazing Benefits For Your Life The Best Tips On How To Keep This Killer At Bay Discovering that you or a loved one has cancer can be utterly terrifying. All the same, once you comprehend the causes of cancer and learn how to reverse those causes, you or your loved one may have more than a fighting chance of beating out cancer.

Get My Free Ebook


Post a comment