Section 3 Biological Compounds

This section covers compounds that were reported relatively recently. The mechanism of action of these compounds is reasonably understood. The compounds in this section have been sorted by their biological activity and their potential utility in the clinic. The class of compounds include immunosuppressants (rapamycin and FK506), antitumor agents (geldanamycin to echinomycin), antiinflammatory agents (efomycin), antiobesity agents (lipstatin), and antibiotics (streptogramins to platensimycin). 

Finally in this section, a Raman spectroelectrochemical microcell [17] is shown in Fig. 7. Having a total volume of 80 pi, this cell is particularly well suited to work with rare and/or expensive samples, such as biological compounds. Its design enables it to be used with a microscope objective as the laser focusing and Raman collection element. Such an arrangement... 

In the following, we classify dioxygen adducts according to the type of ligand involved, and review typical results obtained for each type. For dioxygen adducts of biological compounds, see Section V. 

The CNMRofNa+ and K+ ions in biological compounds will be discussed in the section on biological applications (see Section VII). Sodium cyclopen-tadienyls are included in Section IV Na diketone complexes in section VI. 

Alcohols can also form esters by reacting with inorganic acids such as phosphoric acid, objective 9 (Section 5.8), Exercise 5.56 Phosphate esters represent some of the most important biological compounds. 

Most evident to the modern biochemist, apart from the body of knowledge of the chemistry and metabolism of biological substances, is the extent to which he must draw from recent concepts of physical and organic chemistry, and in turn project into the vast field of biology. Thus in the organization of Comprehensive Biochemistry, the middle three sections. Chemistry of Biological Compounds, Biochemical Reaction Mechanisms, and Metabolism may be considered classical biochemistry, while the first and last sections provide selected material on the origins and projections of the subject. 

The research for new fungicidal compounds forms the second part of this section. Some compounds having nematocidal activity were isolated by preparative TLC from leaves of Piper beetle (piperacae). Their biological activity was checked on the same layer using Phithium ultimum and Cladosporium cucumerinum strains (108) (Table 8). 

To enhance the properties of carbon nanostructures, several strategies have been developed. For example, carbon surfaces are functionalized, modified, and customized to selectively detect molecules, chemicals, and biological compounds in liquid or gas phases. Noncovalent attachment can be utilized to preserve the structure of CNTs by adsorbing the material onto their surface. However, covalent attachment needs the surface of CNTs to have defect sites, often requiring the surface to be chemically activated to bind molecules to their surface. Alternatively, CNTs can be embedded or filled with material, as we will discuss later in this section. 

What other measurements can be made which offer a comparison between model and biological compounds Iron is an element which can be studied by Mossbauer spectroscopy (Section 12.5.3). Mossbauer spectroscopy provides a way of determining whether, for instance, the electric field gradient at the iron is similar in model and biological species. The comparison is detailed in Table 16.2. Without going into a detailed discussion of the meaning of the quantities in this table (although Sections 12.5.2 and 12.5.3 provide an indication), it is evident that a reasonable accord exists and this conclusion is confirmed by a more detailed analysis—the iron atoms, indeed, are in similar environments. 

Amino acids are biological compounds that link together to form proteins, the workhorse molecules in living organisms. The skeletal structures of several simple amino acids are shown here. For each skeletal structure, complete the Lewis structure, determine the geometry and hybridization about each interior atom, and make a sketch of the molecule, using the bond conventions of Section 10.4. 

---