TOPICAL primary structure

This chapter is concerned with aspects of the structure of polymeric materials outside those of simple chemical composition. The main topics covered are polymer stereochemistry, crystallinity, and the character of amorphous polymers including the glass transition. These may be thought of as arising from the primary structure of the constituent molecules in ways that will become clearer as the chapter progresses. 

The primary level of structure in a protein is the linear sequence of amino acids as joined together by peptide bonds. This sequence is determined by the sequence of nucleotide bases in the gene encoding the protein (see Topic HI). Also included under primary structure is the location of any other covalent bonds. These are primarily disulfide bonds between cysteine residues that are adjacent in space but not in the linear amino acid sequence. These covalent cross-links between separate polypeptide chains or between different parts of the same chain are formed by the oxidation of the SH groups on cysteine residues that are juxtaposed in space (Fig. 4). The resulting disulfide is called a cystine residue. Disulfide bonds are often present in extracellular proteins, but are rarely found in intracellular proteins. Some proteins, such as collagen, have covalent cross-links formed between the side-chains of Lys residues (see Topic B5). 

In an essay or review, the structure of your writing should help the reader to assimilate and understand your main points. Sub-divisions of the topic could simply be related to the nature of the subject matter (e.g. levels of organization of a protein) and should proceed logically (e.g. primary structures, then secondary, etc.). 

The primary structure of the fluids that are bound to undergo freeze-drying is, of course, of great interest. In that wake, the structure of water itself is a determinant item. This is why two chapters in this book relate directly to that topic (Watts and Bellissent-Funel/Teixeira). Accordingly, we will not deal with it. However, we would like to share with our readers and colleagues some ideas that evolved from recent experiments that we have carried out on the low-temperature thermoluminescence of different systems and, in particular, on water itself. 

The discussion of primary structures is not the main topic of this chapter therefore only a short overview is provided. A roof system consists of the primary structure which has to carry all loads and must be stable in itself without depending upon the membrane. The primary structure forms the... 

References to the primary literature are provided for specific issues of structure, reactivity, and mechanism. These have been chosen to illustrate the topic of discussion and, of course, cannot be comprehensive. The examples and references chosen do not imply any priority of concept or publication. References to general reviews which can provide a broader coverage of the various topics are usually given. 

Searching journal information continues to be the primary use of SciFinder for the medicinal chemist. One finds it especially useful for searching various topics, for instance, anti-inflammatory treatments. When performing structure/reaction-based searches, many chemists also use Beilstein CrossFire in conjunction with SciFinder. The reaction information from these systems is often complementary, and it is quite useful to have both SciFinder and CrossFire in a medicinal chemistry group. However, companies with restricted budget may have to choose one or the other. 

The statistical distribution of r values for long polymer chains and the influence of chain structure and hindrance to rotation about chain bonds on its root-mean-square value will be the topics of primary concern in the present chapter. We thus enter upon the second major application of statistical methods to polymer problems, the first of these having been discussed in the two chapters preceding. Quite apart from whatever intrinsic interest may be attached to the polymer chain configuration problem, its analysis is essential for the interpretation of rubberlike elasticity and of dilute solution properties, both hydrodynamic and thermodynamic, of polymers. These problems will be dealt with in following chapters. The content of the present... 

Systemic therapy with a variety of (3-lactams, macro-lides and lincosamides (clindamycin) has been the cornerstone of skin infection therapy for many years [17]. However, topical antibiotics can play an important role in both treatment and prevention of many primary cutaneous bacterial infections commonly seen in the dermatological practice [18], Indeed, while systemic antimicrobials are needed in the complicated infections of skin and skin structure, the milder forms can be successfully treated with topical therapy alone [18], The topical agents used most often in the treatment of superficial cutaneous bacterial infections are tetracyclines, mupirocin, bacitracin, polymyxin B, and neomycin. 

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