Epidermal polypeptide chains

Figure 2.19 Organization of polypeptide chains into domains. Small protein molecules like the epidermal growth factor, EGF, comprise only one domain. Others, like the serine proteinase chymotrypsin, are arranged in two domains that are required to form a functional unit (see Chapter 11). Many of the proteins that are involved in blood coagulation and fibrinolysis, such as urokinase, factor IX, and plasminogen, have long polypeptide chains that comprise different combinations of domains homologous to EGF and serine proteinases and, in addition, calcium-binding domains and Kringle domains.

Domains that are homologous to the epidermal growth factor, EGF, which is a small polypeptide chain of 53 amino acids. 

Figure 8.8 Proposed assembly of keratin polypeptide chains to form keratin filaments. (Reproduced by permission from Eichner R, Rew P, Engel A, Aebi U. Human epidermal keratin filaments studies on their structure and assembly. Ann NY Acad Sri 455 381-401, 1985.)...

Prekeratin is the protein of the epidermal tonofilaments and the bovine material has now been characterized in some detail Many features of its molecular architecture are known and, most importantly for the purposes of this study, it has been shown to consist of three different polypeptide chains which can be readily detected on sodium dodecyl sulphate (SDS)-polyacrylamide gels. 

Murine epidermal growth factor is a polypeptide containing 53 residues. Its molar mass is 6040 g/mol. Chromatography on diethylaminoethyl cellulose produced a single peak. The isocratic RPC of this seemingly homogeneous material on a C 18 column (300 x 7.8 mm) yielded two clearly separated peaks (Fig. 19)77). The eluent was water — acetonitrile (74 26), 0.04 M in triethylamine acetate, pH = 5.6. The structure of the p component is identical with that of the a component but does not possess the Asn residue at chain position 1. 

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