Chapter 2
Protein Structure and Properties
Biosensors are chemical sensors that recognize target molecules by means of materials of biological origin, including proteins. Two categories of protein are of particular relevance to biosensors, namely enzymes and antibodies. Another type of biomaterial with broad applications in biosensors is polynucleotides that are also known as nucleic acids.
Enzymes, antibodies and nucleic acids have been designed by nature to perform particular tasks that rely on specific interactions with other chemical species. Such compounds can be advantageously used to impart selectivity to biomaterial-based sensors.
In this chapter a short survey of the structure and properties of proteins is given to aid understanding of their behavior in sensor applications. Enzymes, antibodies and nucleic acids are presented in subsequent chapters.
Protein molecules are polymers consisting of a sequence of 
-amino acids residues. Such molecules display a high degree of organization, involving weak and strong bonding interactions between different regions along the length of the molecule as well as bonding interaction between distinct molecules [1, 2].
2.1 Amino Acids
-amino acids have the general structure shown in Figure 2.1. Each molecule has a hydrogen atom, a carboxyl ...
