Protein Facts: Fibrous Proteins in Cultural and Natural History Artifacts Mary-Lou E. Florian

Contents Preface Acknowledgements Introduction The manual Why group heritage artifacts and natural history specimens together? Why is it important to study the basic information on the cellular tissue structure and the protein chemistry of these materials? Hierarchy of structure of the fibrous protein material Basic structure of the different fibrous proteins in the materials The structural strength and other physical-chemical characteristics of proteinaceous materials The colloidal nature of the proteins An interdisciplinary approach The structure of the skin and its derivatives, and other collagenous tissues used in heritage objects The skin of vertebrates Introduction Epidermis Dermis Colours in the skin Fish skins General structure Epidermis Dermis Reptile skins Introduction Snakes and lizards Crocodiles and alligators Turtles Birds Structures of epidermal skin and extensions (scales, claws, beaks and feathers) Structural colours Mammalian skins and structures of epidermal origin Hair structure, species identification, colour, moulting, modified hairs and deterioration Horn Claws, nails and hooves Skin of marine mammals Gut, ligament and tendons Biologically mineralized tissue: mammalian teeth and bones Enamel and dentin structures: teeth and ivory Bony structures: bones and antlers Amino acids: the building blocks of fibrous proteins General structure of fibrous proteins Amino acids What is the role of amino acids? General characteristics of amino acids Amino acid reactions and changes Agents of protein deterioration Introduction Water and hydrolysis Water as a liquid and vapour Some reactions involving water Oxygen, light and lipids Oxygen Free radicals, light and lipids Air pollution gases: ozone, sulphur dioxide, nitrogen dioxide and carbon dioxide Ozone Sulphur dioxide Nitrogen dioxide Carbon dioxide Metals and salts Heat Water in fibrous protein materials Introduction The nature of water The states of water and energy of change Vapour pressure and the activity of water Water vapour in the air Relative humidity (RH), absolute humidity (AH) and temperature The importance of the dew point and microenvironments The characteristics of water in fibrous and colloidal materials Location and properties of water in the protein materials Release of water from drying materials Equilibrium moisture content (EMC) and regain ability of materials Hysterical hysteresis Chemicals in materials: changes in water activity (a(W)) in materials Colloids What are colloids? Gelatin and the importance of the glass transition point The role of water and biodeterioration Collagen structure Introduction Molecular organization Polypeptide chain: the protein molecule Three-chained molecule: tropocollagen Water in the collagenous material: inside and outside Tanning: processes, deterioration and interaction with collagen Introduction Pre-tanning processes Tanning processes Smoking Oil process and chamois tannage Alum tawing Vegetable tanning Chrome tanning Chewing Finishing processes Parchment Deterioration of collagen Bonds in collagen: sites of deterioration Chemical changes in deterioration in dry collagen and leather Chemical deterioration of collagen polymer into peptides Amino acid changes in deteriorated leather Physical changes due to hydration of collagen in wet skins, leather and natural history specimens The water in wet skins Swelling of collagen Influence of salts and others deteriorating agents on hydrated collagen Acid and alkaline conditions: pH Neutral salts Non-electrolytes Radiation Biodeterioration Denaturation and shrinkage temperature of hydrated collagen Denaturation Shrinkage temperature Shrinkage temperature as a method of assessment of the deterioration state of collagenous materials Collagen changes in natural history specimens due to preservation methods Effects of alcohols on hydrated collagen in liquid storage of natural history specimens Effects of aldehydes on hydrated collagen in liquid storage of natural history specimens Reported interactions of many natural history preparation methods on collagen Keratin Molecular organization: coiled coils Cellular organization: keratinization of tissue Keratin as a colloid Chemical reactivity of keratin Introduction Chemical deterioration Biodeterioration Silk Source Structure of fibroin Reactivity of fibroin Deterioration by metals used in weighting silk Analysis of deterioration of fibroin polymer Striated muscle and elastin in fluid-preserved natural history specimens The fluids and their chemicals Striated muscle proteins Muscle tissue and function Myosin and actin Elastin Post-mortem changes Bibliography Index