Structural degradation, types

The first paper on the bioactive polysaccharides from Glycyrrhiza uralensis roots was published in 1996 by Kiyohara et al. [57]. They isolated a pectic type polymer with anti-complementary and mitogenic activity that was an acidic pectin, possibly containing rhamnogalacturonan type I as part of the total structure. Degradation of the uronic acid part of the molecule decreased both types of bio activities. The neutral oligosaccharide chains were shown to retain some of the activities of the native polymer, but it was suggested that they should be attached to the acidic core to retain maximum activity. 

It was mentioned earlier that catalytic hydrogenation of protoporphyrin-IX (19) produces mesoporphyrin-IX (46), and that this type of vinyl modification has been used in structural degradation methods. The vinyl group can also be modified for degradative purposes by addition of diazoacetic ester, which produces the corresponding cyclopropane derivatives... 

M. A. Uddin, K. Koizumi, K. Murata, and Y. Sakata, Thermal and catalytic degradation of structurally different types of polyethylene into fuel oil, Polym. Degrad. Stab., 56, 37-44 (1997). 

Glucuronic acid and sialic acid are normally present in conjugated forms. After degradation of these components in lysosomes, the free monosaccharides are released by a specific membrane transport system. The lysosomal sialic acid transporter from rat liver has been purified to apparent homogeneity in a reconstitutively active form. The transporter recognized structurally different types of acidic monosaccharides such as sialic acid, glucuronic acid, and iduronic acid. The transport was proton gradient dependent, and saturable with a of approximately 0.4mM [211]. 

The following is a review of methods to introduce liquids into the wood structure. The type of degradation that has occurred must be known to determine what method will best match the state of the artifact. 

Collagaiase I-III - The dense network of collagen fibers of the extracellular matrix is inpenetrable to most cells. Invasive cells, such as inflannatory cells and tumor cells produce matrix degrading enzymes in order to cross tissue boundaries. Destruction of the extracellular matrix during tumor invasion has been ctoserved histologically and ultra-structurally various types of tumor cells have been found to... 

R. Hales, A quantitative metaUographic assessment of structural degradation of type 316 stainless steel during creep-fatigue. Fat. Eng. Mat. Struct. 3 (4) (1980) 339—356. 

---