Collagen hard/soft tissues

Since the collagen of mineralized connective tissues is the predominating organic constituent, it might be expected to differ substantially from the collagen of soft tissues, such as skin and tendon. In fact, hard and soft tissue collagens are surprisingly alike in their main structural aspects and amino add composition. 

Sarkar, S. K., Sullivan, C. E., and Torchia, D. A. (1983). Solid state 13C NMR study of collagen molecular dynamics in hard and soft tissues./. Biol. Chem. 258, 9762-9767. 

Modification of Collagenous Surfaces by Grafting Polymeric Side Chains to Collagen and Soft and Hard Tissues... 

Collagen 0.002-0.2 Enzymatic Hard and soft tissue repair Drug delivery [5,79,81,83]... 

Teeth, the hard conical structures embedded in their jaws that vertebrate animals use to chew food, consist of two layers of compact matter surrounding a core of soft, living tissue. The inner layer is composed of dentine, also known as ivory, whose composition is similar, but not identical, to that of bone it contains less collagen and is harder than bone. The thin outer layer of the teeth, the teeth s enamel, includes even less collagen and other organic matter than dentine and is the hardest substance produced by animals (Hilson 1986a Kurten 1986b 1982). 

In contrast to soft biologies, whose mechanical properties primarily depend upon the orientation of collagen fibers, the mechanical properties of mineralized tissues, or hard biologies, are more complicated. Factors such as density, mineral content, fat content, water content, and sample preservation and preparation play important roles in mechanical property determination. Specimen orientation also plays a key role, since most hard biologies such as bone are composite structures. For the most part, we will concentrate on the average properties of these materials and will relate these values to those of important, man-made replacement materials. 

Reconstituted acid-soluble collagen from various mineralized and unmineralized tissues have been examined for their potential to pick up calcium and phosphate from buffered solutions, and for their capacity to induce nucleation of a mineral phase426-434. Some collagens were good, others poor catalysts428,429 and apatite deposition proceeded in the presence of soft as well as of hard tissue collagens. The uptake of calcium ions requires the presence of phosphate ions and vice versa the Ca/P ratio is close to that of apatite (1.5—1.8)431. Study of exchange reactions by isotope tracers between solvent und substrate revealed that in absence of either... 

In invertebrates, collagen is uncalcified, whereas in vertebrates it occurs in the form of soft and hard tissue. Remains of the earliest vertebrates — bony armour — are found in sediments of the Ordovician (ca. 500 million years). At about that time, conodonts appeared in the stratigraphic column mineralogically they are carbonate apatite. Conodonts are small tooth-shaped fossils 0.2 to 3 mm in size whose origin is in doubt they are most likely remains of some unknown chordata that became extinct in Triassic time516. ... 

Phosphates are found in soft organic tissues as phosphate esters, and in hard tissues, notably bones and teeth, as solid calcium orthophosphates see Biomineralization). Hard tissues are composites of Apatite and an organic matrix collagen in bone, dentin, and dental cement, and keratin in dental enamel. The Apatite phases are defective with Ca/P ratios of 1.6-1.8 and can incorporate other cations (Na+, K+, Mg +) or anions (F , d , COs ", citrate). 

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