Biochemistry, 4th Edition P17. Continuing Garrett and Grisham's innovative conceptual and organizing framework, "Essential Questions," BIOCHEMISTRY guides students through course concepts in a way that reveals the beauty and usefulness of biochemistry in the everyday world. Streamlined for increased clarity and readability, this edition also includes new photos and illustrations that show the subject matter consistently throughout the text. New end-of-chapter problems, MCAT practice questions, and the unparalleled text/media integration with the power of CengageNOW round out this exceptional package, giving you the tools you need to both master course concepts and develop critical problem-solving skills you can draw upon. | Summary 123 mentary to the structure of the ligand its charge distribution and any H-bond donors or acceptors it might have. Structural complementarity within the binding site is achieved because part of the three-dimensional structure of the protein provides an ensemble of amino acid side chains and polypeptide backbone atoms that establish an interactive cavity complementary to the ligand molecule. When a ligand binds to the protein the protein usually undergoes a conformational change. This new protein conformation provides an even better fit with the ligand than before. Such changes are called ligand-induced conformational changes and the result is an even more stable interaction between the protein and its ligand. Thus in a general sense most proteins are binding proteins because ligand binding is a hallmark of protein function. Catalytic proteins enzymes bind substrates regulatory proteins bind hormones or other proteins or regulatory sequences in genes structural proteins bind to and interact with each other and the many types of transport proteins bind ligands facilitating their movement from one place to another. Many proteins accomplish their function through the binding of other protein molecules a phenomenon called protein-protein interaction. Some proteins engage in protein-protein interactions with proteins that are similar or identical to themselves so that an oligomeric structure is formed as in hemoglobin. Other proteins engage in protein-protein interactions with proteins that are very different from themselves as in the anchoring proteins or the scaffolding proteins of signaling pathways. SUMMARY The primary structure the amino acid sequence of a protein is encoded in DNA in the form of a nucleotide sequence. Expression of this genetic information is realized when the polypeptide chain is synthesized and assumes its functional three-dimensional architecture. Proteins are the agents of biological function. What Architectural Arrangements .
