Globular proteins biological function

In the field of biology, the effects of hydration on equilibrium protein structure and dynamics are fundamental to the relationship between structure and biological function [21-27]. In particular, the assessment of perturbation of liquid water structure and dynamics by hydrophilic and hydrophobic molecular surfaces is fundamental to the quantitative understanding of the stability and enzymatic activity of globular proteins and functions of membranes. Examples of structures that impose spatial restriction on water molecules include polymer gels, micelles, vesicles, and microemulsions. In the last three cases since the hydrophobic effect is the primary cause for the self-organization of these structures, obviously the configuration of water molecules near the hydrophilic-hydrophobic interfaces is of considerable relevance. 

Many globular proteins are enzymes They accelerate the rates of chemical reactions m biological systems but the kinds of reactions that take place are the fundamental reactions of organic chemistry One way m which enzymes accelerate these reactions is by bringing reactive func tions together m the presence of catalytically active functions of the protein... 

Because of the structure-function relationship for (globular) proteins, adsorption-induced changes in the molecular structure are likely to affect the biological activity of the protein, e.g., the enzymatic activity. In soils, as well as in a wide variety of other systems, the impact on biological... 

Table 4-2 shows the proportions of a helix and J8 conformation (expressed as percentage of residues in each secondary structure) in several small, single-chain, globular proteins. Each of these proteins has a distinct structure, adapted for its particular biological function, but together they share several important properties. Each is folded compactly, and in each case the hydro-... 

Typically, proteins fold to organize a very specific globular conformation, known as the protein s native state, which is in general reasonably stable and unique. It is this well-defined three-dimensional conformation of a polypeptide chain that determines the macroscopic properties and function of a protein. The folding mechanism and biological functionality are directly related to the polypeptide sequence a completely random amino acid sequence is unlikely to form a functional structure. In this view, polypeptide sequence... 

Intramolecular hydrogen bonds between different components of molecules stabilize conformation. They are among the most important interactions in small and in large biological molecules because they require particular molecular conformations to be formed, and when formed, they confer additional rotational stability to these conformations. They ultimately help to determine and to define the three-dimensional structures of the molecules, and are therefore involved in their functional aspects. These bonds are of major importance in the globular proteins, where all the secondary and tertiary structure hydrogen bonds are of this type. In polypeptides, the NH 0=C bonds between peptide bonds (n) and (n+3) give rise to / -turns and to 310 helices, and between bonds (n) and (n+4) to a-helices (see Part III, Chapt. 19). 

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