Connective tissue protein

Walz, A., Dewald, B., von Tscharner, V., and Baggiolini, M. (1989). Effects of the neutrophil-activating peptide NAP-2, platelet basic protein, connective tissue-activating peptide III and platelet factor 4 on human neutrophils. J. Exp. Med. 170, 1745-1750. 

Fresh or Frozen Tissue and Cells Human cell cultures and most human tissues can be efficiently lysed using lysis buffer and protease or proteinase K. Fresh or frozen tissue samples should be cut into small pieces to aid the lysis. Mechanical disruption using a homogenizer, mixer mill, or mortar and pestle prior to lysis can also reduce the lysis time. Skeletal muscle, heart, and skin tissue have an abundance of contractile proteins, connective tissue, and collagen, and special care should be taken to ensure complete digestion using protease or proteinase K. 

At least two types of protein hydrolysates have been extensively studied, only one of which will be discussed in detail. The first is represented by gelatin, which is in reality a mild hydrolysate of connective tissue protein, although it is often considered to be a solution of whole protein. Connective tissue protein is obtained in solution by boiling the tissue, usually bone or skin, and extracting it in this way. 

Insoluble proteins (connective tissue and membrane proteins). 

Scieroproteins. Insoluble proteins obtained from the skeletal and connective tissues of animals. Typical classes are keratins collagens and elastin classes. 

Protein-Based Adhesives. Proteia-based adhesives are aormaHy used as stmctural adhesives they are all polyamino acids that are derived from blood, fish skin, caseia [9000-71 -9] soybeans, or animal hides, bones, and connective tissue (coUagen). Setting or cross-linking methods typically used are iasolubilization by means of hydrated lime and denaturation. Denaturation methods require energy which can come from heat, pressure, or radiation, as well as chemical denaturants such as carbon disulfide [75-15-0] or thiourea [62-56-6]. Complexiag salts such as those based upon cobalt, copper, or chromium have also been used. Formaldehyde and formaldehyde donors such as h exam ethyl en etetra am in e can be used to form cross-links. Removal of water from a proteia will also often denature the material. 

J. E. Eastoe and A. Courts, Practical Mnalytical Methods for Connective Tissue Proteins, Spon, London, 1963, Chapt. 6. 

Estrogens stimulate cellular proliferation, induce RNA and protein synthesis of uterine endometrium and the fibrous connective tissue framework for ovaries, and increase the size of the cells. This effect leads to the growth and regeneration of the endometrial layer and spinal arterioles, and increase in the number and size of endometrial glands. Under the influence of estrogen, vaginal mucosa becomes thicker, as cervical mucus becomes thinner (85,86). 

Proteins can be broadly classified into fibrous and globular. Many fibrous proteins serve a stmctural role (11). CC-Keratin has been described. Fibroin, the primary protein in silk, has -sheets packed one on top of another. CoUagen, found in connective tissue, has a triple-hehcal stmcture. Other fibrous proteins have a motile function. Skeletal muscle fibers are made up of thick filaments consisting of the protein myosin, and thin filaments consisting of actin, troponin, and tropomyosin. Muscle contraction is achieved when these filaments sHde past each other. Microtubules and flagellin are proteins responsible for the motion of ciUa and bacterial dageUa. 

Proteins. The most abundant and physiologically diverse natural biopolymers are proteins, which make up enzymes, hormones, and stmctural material such as hair, skin, and connective tissue. The monomer units of natural proteins, a-amino acids, condense to form dipeptides, tripeptides, polypeptides, and proteins. 

FIGURE 4.4 The structures of several atniuo acids that are less cotntnou but nevertheless found in certain proteins. Hydroxylysine and hydroxyproline are found in connective-tissue proteins, pyroglutatnic acid is found in bacteriorhodopsin (a protein in Halohacterium halohium), and atninoadipic acid is found in proteins isolated from corn. 

Collagen is a rigid, inextensible fibrous protein that is a principal constituent of connective tissue in animals, including tendons, cartilage, bones, teeth, skin, and blood vessels. The high tensile strength of collagen fibers in these struc-... 

Ascorbic acid—vitamin C—is an essential nutrient that the human body cannot manufacture from other compounds. It is needed for the formation of collagen, the protein that makes up connective tissue, and is essential to muscles, bones, cartilage, and blood vessels. It is a strong antioxidant, preventing damage from oxygen free radicals. 

Gelatin is a protein, made from the hydrolysis of collagen, a protein that makes up about a third of all mammalian tissue. Collagen is a key component of connective tissues, tendons, and bones. 

The citric acid cycle is the final common pathway for the aerobic oxidation of carbohydrate, lipid, and protein because glucose, fatty acids, and most amino acids are metabolized to acetyl-CoA or intermediates of the cycle. It also has a central role in gluconeogenesis, lipogenesis, and interconversion of amino acids. Many of these processes occur in most tissues, but the hver is the only tissue in which all occur to a significant extent. The repercussions are therefore profound when, for example, large numbers of hepatic cells are damaged as in acute hepatitis or replaced by connective tissue (as in cirrhosis). Very few, if any, genetic abnormalities of citric acid cycle enzymes have been reported such ab-normahties would be incompatible with life or normal development. 

Collagen, the major component of most connective tissues, constimtes approximately 25% of the protein of mammals. It provides an extracellular framework for all metazoan animals and exists in virmally every animal tissue. At least 19 distinct types of collagen made up of 30 distinct polypeptide chains (each encoded by a separate gene) have been identified in human tissues. Although several of these are present only in small proportions, they may play important roles in determining the physical properties of specific tissues. In addition, a number of proteins (eg, the Clq component of the complement system, pulmonary surfactant proteins SP-A and SP-D) that are not classified as collagens have... 

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