Heritable disorders of connective tissue

Publisher Summary This chapter reviews that collagen constitutes the major protein component of skin, bone, tendon, and all the other forms of connective tissue. An understanding of collagen seems to the clinician to be a necessary prerequisite to a rational attack on many and diverse connective tissue disorders currently lumped together as “collagen diseases.” The unusual amino acid composition of collagen had also been recognized for some time. One-third of the residues of all collagens seemed to be glycine, while about one-fourth were proline and hydroxyproline. However, the stereochemical consequences of the presence of these residues has only become clear as a result of the detailed studies of synthetic homo- and copolymers of glycine and proline. Consideration of such synthetic polypeptides as simplified models of certain features of collagen and gelatin has been extremely helpful in recent years, and constitutes the rationale for the inclusion of a section dealing specifically with these synthetic polypeptides in this chapter. It also reviews that the collagen ⇆ gelatin transformation in solution has been recognized as a reversible first-order phase transition, subject to the same physical laws which govern the crystalline ⇆ amorphous phase transitions observed in systems of linear polymers. The direct relationship between the transition in solution and the well-known thermal shrinkage phenomenon exhibited by collagen fibers has also been established.

The structure of collagen and gelatin.

All multicellular organisms contain a framework of solid material which in part maintains their shape. The commonest of the materials used to make such frameworks are long chain carbohydrate polymers, for example cellulose, found in plants. In animals, however, these simple materials are not used to any extent, though cellulose has been recorded in ascidians (Schmidt, 1845; Ranby, 1952; van der Wyk & Schmorak, I 953). Materials of primarily carbohydrate origin are certainly concerned and may sometimes form a large part of the structural material, for example chitin in invertebrates, but the dominant structural materials are proteins; and of these the collagens appear to be the most important and widely distributed. There are other proteins of structural importance, found, for example in the arthropod cuticle (' arthropodine', see Fraenkel & Rudall, 1947; Duchateau & Florkin, 1954); in the hard skeletons of insects (see Richards, 1951; Wigglesworth, 1957); keratin in vertebrate hair and epidermis (see Kendrew, 1954; Ward & Lundgren, 1954); but these, with the exception of keratin, are as yet poorly defined and are restricted in distribution. The collagens appear to be characteristic structural proteins of soft tissues of all animals, but are perhaps typically the dominant structural materials in vertebrates, in which they may constitute up to a quarter of all the body protein. Collagen is a fibrous protein; that is to say, the individual molecules are thread-like, and are arranged together in threads of higher orders of size to form a continuous framework throughout the body. This fibrous framework is closely associated with other materials filling spaces within it and cementing it together. Such materials include crystalline solids, as in bone, but generally they appear to be gels containing a high proportion of water, associated with acid mucopolysaccharides, that is,

Biological functions of collagen

Excerpt Essentially all the hydroxyproline in the tissues of vertebrates is found in collagen, and, except for the small amount of hydroxyproline in elastin, no other animal protein contains signif...

Relationship of Hydroxyproline Excretion in Urine to Collagen Metabolism

Relationship of Hydroxyproline Excretion in Urine to Collagen Metabolism: Biochemistry and Clinical Applications

1. The presence of astaxanthin in the shell of Ophidiaster ophidianus is confirmed, and that of #-carotene and cryptoxanthin demonstrated. neop-Carotene B and y-carotene are also probably present. 2. Three new pigments are reported: two are probably keto-carotenoids. 3. The quantitative distribution of carotenoids in the shell of 0. ophidianus is recorded. 4. A possible biosynthetic route from ,-carotene to astaxanthin is discussed.

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A. M. Marko

Papers

The metabolism of collagen and other proteins of the skin of rabbits.