Degradation, LEDs

Conventionally, the first attribute known about an enzyme used to be its function, usually in a crude extract. This property was screened for in microbial cultures or in tissue samples. The crude extract was then purified to homogeneity and the protein subjected to biochemical studies to learn of its pH and T profiles, its pi and subunit composition, catalytically important residues, and other properties. Proteolytic digestion of the protein with subsequent Edman degradation led to the primary sequence, but no information on the secondary structures such as a-heli-ces and [5-sheets or the folding in three dimensions of the polypeptide chain. The primary sequence could have been used to deduct the gene sequence but, with the degeneration of the code, several possibilities for certain amino acids occur, which makes prediction of the gene sequence a risk. 

The Hofmann and Emde degradations led to many interesting transformations, none of which, however, helped to shed light on the structural problem. 

Thermal degradation led to the oxo compounds including [(N02)N0)][Ti0(F3CS03)4], Tilv triflate complexes efFiciently catalyze a variety of reactions including the conversion of acetophenones to 1,3,5-triarylbenzenes,658 the nucleophilic ring opening of epoxides,659 Diels—Alder reactions,660 selective Claisen and Dieckmann ester condensations,661 esterification reactions,662 Fries rearrangements,663 homoaldol reactions,664 sequential cationic and anionic polymerizations,641 and the stereoselective synthesis of m-arabinofuranosides.606... 

Kaminsky90,92 has reported the product distribution obtained in the fluidized bed pyrolysis of different condensation polymers (polyesters, polyurethanes, polyamides, etc.). Polyester degradation led to 51% of gases, with a high proportion of CO and C02, and 40% of oil rich in benzene, toluene and naphthalene, the formation of water also being detected. On the other hand, polyurethane and polyamide decomposition led to the formation of about 40% gases and 55% oil. In both cases, the gases obtained contained certain amounts of HCN. 

The compound was quite obviously an amine due to its basic character. Von Braun degradation (NMe - NCN) and Hofmann degradation (sequential methylation -elimination) implied a cyclic tertiary amine. Further exhaustive Hofmann degradation led to an unusual net elimination of both trimethylamine and ethylene. (This reaction was driven by aromatization of the C-ring after elimination of the Q5-C16-N17 ethylamine bridge). 

Aconitum and Delphinium Alkaloids. Cjo-Skeleton.—Staphisine. The structure of staphisine has been determined using A-ray crystallographic techniques. This diterpene alkaloid dimer was first isolated from the mother liquors accumulated in the extraction of delphinine from Delphinium staphisagria in 1941. Chemical studies of this compound were hindered by its instability and by the fact that attempted degradation led to complex changes involving numerous unstable products. 

The metabolism of the 4-deoxy-L-f/ireo-hex-4-enopyranuronate (54) fragment obtained from n-galacturonans by enzyme-catalyzed, y8-elimina-tive degradation led to a new intermediate (76) and, thence, to 3-deoxy-n-gZycefo-2,5-hexodiulosonic acid (77). Reduction of 77 gave 78. The new... 

Sequence analysis by means ofthe Edman degradation led to the structure ofthe peptide. 

A case was reported in textile industry. Dimethoxane was used as a biocide agent in textiles and its degradation led to acetaldehyde. 

Corydalis ochotensis Turcz. contains, among other alkaloids, the pair ochotensine, C21H21O4N, and ochotensimine [noncrystalline methiodide, mp 225°], the 0-methyl ether of the former. Attempted Hofmann degradation led to insoluble polymeric products but Emde degradation... 

The search for more highly sensitive polymers that function via main-chain backbone degradation led in one case to the poly(olefin sulfone) class of polymers. These polymers, whose structure has been known since 1934, were shown to be efficiently degraded by y radiation by Brown and coworkers in 1970, who studied poly(butane-l-sulfone)... 

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