Protein aggregation and biological water

In this chapter we have introduced the concept that water in biological systems is quite different from bulk water that we are so familiar with and that has been studied extensively over many decades. In contrast, the study of water in biological systems has just begun. The reason for such a late start is not any lack of interest. Rather, experimental systems (water in and around proteins, DNA hydration later, etc.) were not amenable to study even in vitro. In vivo study of water in important systems is still largely an unexplored area. 

Reeent studies in different systems seem to reveal certain commonalities that have motivated the use of the term biological water to distinguish water in biologieal systems. First and foremost, the extended hydrogen-bond network present in bulk water is mostly lost near a biomolecular surface. Second, water can exist in different states. These molecules differ in their coordination with other water moleeules and with the surface of proteins or DNA or tissues. The term biological water serves to emphasize this difference between water in biology and the one we 

The attempt to classify the behavior of water in biological systems under one common umbrella is an effort not devoid of ambiguity. Unlike bulk water, here properties can vary substantially from system to system, as we shall see in the chapters to follow. 

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