Beta-keratin 75-80% of the amino acids in silk, another 10-15% is serine and the final 10% contain bulky side chains such as in tyr, arg, val, asp, and glu. Beta-keratin β-keratin or beta-keratin is a member of a structural protein family found in the epidermis of reptiles and birds . β-keratins were named so because they are components of epidermal stratum corneum rich in stacked β pleated sheets, in contrast to alpha-keratins, intermediate-filament proteins also found in stratum corneum and rich in alpha helices. Because the accurate use of the term "keratin" is limited to the alpha-keratins, the term "beta-keratins" in
Collagen collagen all contribute to the compliance required to move blood back and forth. Individual cardiac valvular leaflets are folded into shape by specialized collagen under variable pressure. Gradual calcium deposition within collagen occurs as a natural function of aging. Calcified points within collagen matrices show contrast in a moving display of blood and muscle, enabling methods of cardiac imaging technology to arrive at ratios essentially stating blood in (cardiac input) and blood out (cardiac output). Pathology of the collagen underpinning of the heart is understood within the category of connective tissue disease. Collagen has been widely used in cosmetic surgery,