The Structure of Gelatin

The dissociation of the polypeptide chains of collagen by thermal or chemical processes leads to products variously termed gelatin. In the present section we propose to consider certain of the physicochemical properties of gelatin, looking toward a deeper understanding of the structure and chemistry of collagen. 

However, despite the expected heterogeneity, studies of gelatin systems have made possible a much deeper insight into the molecular properties of collagen and, indeed, have made substantial contributions to other areas of polymer and protein chemistry. 

The second process involves soaking skin, bone, or tendon in dilute acid. 

The Molecular Properties of Gelatin at Room Temperature and Above 1. Size and Shape 

The presence of covalent cross-linkages in the neutral-salt and citrate- 

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BlO. Bergmann, M., Complex salts of amino acids and peptides. II. Determination of f-proline with the aid of rhodanilic acid. The structure of gelatin. J. Biol. Chem. 110, 471-479 (1935). 

The obtained results on chemiluminescence emission from gelatine materials confirmed that this technique can be a useful tool to characterize the solid state of gelatines. It can be applied to different commercial grades and applications for oxidation control during the manufacture and use of gelatines, and is able to quantify the oxidation that is produced by microorganism in the structure of gelatine due to... 

The fringed-micelle model was an early attempt to inter-relate long molecules, small crystals and a sea of amorphous material. It was proposed in 1930, by Hermans and others, to explain the structure of gelatin and was subsequently applied to natural rubber. It is now believed to be incorrect as the basic model for polymer crystallites, but it is worth describing for historical reasons and because it may be a good approximation to the true structure in special cases. The essentials of the model are illustrated in fig. 5.2. 

If gelatine, or starch, etc., is placed in water, it absorbs the latter and produces a flabby mass. At the same time heat is evolved. This is supposed to result from the work done hy an unknown tension P, which tends to open out the structure of the colloid. 

Murata, K. J. (1946). The significance of internal structure of gelatinizing silicate minerals. Contributions to Geochemistry, 1942-5. In Geological Survey Bulletin, No. 950, 25-33. 

The Structure of Collagen and Gelatin William F. Harrington and Peter H. Von Hippel... 

Lippens (48) has studied the texture of the catalytically active aluminas by means of diffraction and adsorption techniques. He concluded that the structure of tj-alumina formed from bayerite consists of lamellae with an average thickness of about 15 A and a distance of about 25 A. y-Alumina prepared from gelatinous boehmite is composed of fibrillar-shaped particles of about 30 X 30 A. Both structures can easily account for the pseudosolvent effect of alumina, which will be referred to in more detail in the forthcoming discussion. 

Nature often uses cystine knots of variable complexity to assemble polypeptide chains in the correct order and to stabilize the structure of the resulting proteins. Classical examples are proteins of the extracellular matrix with collagens and gelatines as the main components. This simple cystine-knot approach has been applied to synthetic constructs to ligate in a desired order helix bundles. [166 170 194-1%] It has also been used to mimic natural multiple-chain containing proteins like collagen.[83 1691971... 

For this purpose it has been found necessary to destroy entirely the structure of the original cellulose by thoroughly gelatinizing it... 

Gelatin structures have been studied with the aid of an electron microscope (23). The structure of the gel is a combination of fine and coarse interchain networks the ratio depends on the temperature during the polymer-polymer and polymer-solvent interaction leading to bond formation. The rigidity of the gel is approximately proportional to the square of the gelatin concentration. Crystallites, indicated by x-ray diffraction pattern, are believed to be at the junctions of the polypeptide chains (24). 

The above bis ester (2.5 g) was refluxed with sodium bicarbonate (1.64 g) in ethanol (100 ml) and water (50 ml) for 1.5 hours. The whole was poured into water and acidified to precipitate a gelatinous solid. This was collected by filtration, refluxed with ethanol and the product was separated by centrifugation (1.4 g), mp 303°-304°C dec. The structure of the product was confirmed by mass and NMR evidence. 

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