quaternary structure definition by American Heritage Dictionary
nounThe American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The structure formed by the noncovalent interaction of two or more macromolecules, such as that formed by four globin protein molecules to make hemoglobin or that formed by histones interacting with DNA to make a nucleosome.