Large Molecules Problem Set

Large Molecules Problem Set

Problem 7: Weak forces involved in interactions between macromolecules

Tutorial to help answer the question

Two macromolecules, such as proteins, can adhere tightly and specifically to each other. How can weak forces such as electrostatic attraction, van der Waals bonds, hydrogen bonds, and hydrophobic forces lead to such strong adherence?

Tutorial

Non-covalent bonds and other weak forces are important in biological structures.

Electrostatic bonds (ionic) result from the electrostatic attraction between two ionized groups of opposite charge, such as carboxyl (-COO-) and amino (-NH3+). In water, these bonds are very weak, but in a hydrophobic environment such as a protein-protein contact, they are stronger.

Hydrogen bonds result from electrostatic attraction between an electronegative atom (O or N) and a hydrogen atom that is bonded covalently to a second electronegative atom.
(N-H ----- O=C-) or (-O-H----- O=C-)

Van Der Waals bonds are short range attractive forces between chemical groups in contact. They are caused by slight charge displacements that allow the electrons of one atom to be attracted by the protons of another atom.

Hydrophobic attractions cause non-polar groups such as hydrocarbon chains to associate with each other in an aqueous environment.

Multiple weak bonds or forces can cause strong interactions Biological recognition results from a three dimensional structure that allows multiple weak forces between molecules.

The Biology Project
Department of Biochemistry and Molecular Biophysics
The University of Arizona
Revised: February 5, 2003
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