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Chapter

Cover Pharmaceutical Chemistry

Proteins and Enzymes  

Alex White and Helen Burrell

This chapter talks about proteins. These make up a highly important class of macromolecules in biochemistry and are considered to be biopolymers constructed from amino acid monomers. Compared with nucleic acids, proteins have varied and complex three-dimensional structures, due in part to the greater variety of monomers used to construct them. The chapter describes the unique three-dimensional structure of protein which is directly related to the function it performs. The chapter covers the detail of the structures, citing a myriad of functions in cells and organelles, such as antibodies, collagen, membrane-bound receptors, and enzymes. Enzymes and receptors are of particular importance to pharmacy as many drugs interact with them to bring about their therapeutic activity.

Chapter

Cover An Introduction to Medicinal Chemistry

Enzymes: structure and function  

This chapter discusses the structure and function of enzymes, which are proteins that act as the body's catalysts by binding substrates and participating in the reaction mechanism. It examines the active site of an enzyme. This is usually a hollow or cleft in the protein. Here, important amino acids are present and these either bind substrates or participate in the reaction mechanism. The chapter also explains substrate binding, showing how this involves an induced fit where the shape of the active site alters to maximize binding interactions. The chapter reviews the Michaelis constant, which is equal to the substrate concentration at which the rate of the enzyme-catalysed reaction is half of its maximum value. The chapter finally mentions the Lineweaver–Burk plot and illustrates that this provides more accurate values for the maximum rate and K M.

Chapter

Cover An Introduction to Medicinal Chemistry

Protein kinase inhibitors as anticancer agents  

This chapter discusses protein kinases, which are enzymes that phosphorylate specific amino acid residues in protein substrates. It aruges that protein kinases are important targets for anticancer drugs as they are involved in signal transduction pathways controlling cell growth and division. It also highlights the hinge region of a protein kinase that links two distinct lobes of the protein kinase and is often involved in the binding of kinase inhibitors. The chapter analyzes gatekeeper residue, which is an amino acid residue located at the entrance of a hydrophobic pocket and is important in binding some kinase inhibitors. It describes the size of the gatekeeper residue and its importance for selectivity as it determines whether inhibitors can access the hydrophobic pocket.

Chapter

Cover An Introduction to Medicinal Chemistry

Protein structure and function  

This chapter focuses on primary structure, which is the order in which amino acids are linked together in a protein. The secondary structure of a protein refers to regions of ordered structure within the protein. The chapter highlights proteins that contain two or more subunits and have a quaternary structure that defines how the subunits are arranged with respect to each other. It also looks at secondary, tertiary, and quaternary structures. These are formed to maximize favourable intramolecular and intermolecular bonds and to minimize unfavourable interactions. The chapter analyzes amino acids with polar residues. These are favoured on the outer surface of a protein because this allows hydrogen-bonding interactions with water. The chapter talks about transport proteins which carry essential polar molecules across the hydrophobic cell membrane.