Enzymes bond cleavage

Flitsch, S.L, Lahja, S., Turner, N.J. Solid phase preparation and enzymic and non-enzymic bond cleavage of sugars and glycopeptides, PCT Int. Appl. 1997, patent EP 9605535, CAN 127 81736. 

Wyss, A., Carotene oxygenases a new family of double bond cleavage enzymes, J. Nutr. 134, 246S, 2004. 

Goda M, Y Hashimoto, S Shimizu, M Kobayashi (2001) Discovery of a novel enzyme, isonitrile hydratase, involved in nitrogen-carbon triple bond cleavage. J Biol Chem 276 23480-23485. 

Other claimed matter DBT for enrichment, biocatalyst preparation contacting process Enzymes contacting process Pure compounds as feedstock Membrane fragments and extracts Cell-free extract (envelope and its fragments + associated enzyme) reversible emulsion microemulsion reverse micelles Cell-free enzyme preparation microemulsified process RR and derivatives and other biocatalyst concepts + any known microorganism active for C—S bond cleavage... 

Kilbane II, J. J., Bacterial produced extracts and enzymes for cleavage of organic C-S bonds. Patent No. EP0445896. 1991, Sep. 11. (Also published as US5132219). 

Bacterial produced extracts and enzymes for cleavage of organic C—S bonds [68],... 

These two strains, B. sphaericus strain ATCC 53969 and R. rhodochrous strain ATCC 53968 discovered by Kilbane as being capable of dibenzothiophene desulfurization were patented as two separate (European) patents [67,91], respectively. These two patents issued by 1991 also described the use of the enzymes derived from these organisms and their cell-free extracts for desulfurization applications. Both strains were reported to carry out selective cleavage of C—S bonds in organic carbonaceous materials. The organism, Bacillus sphaericus strain ATCC 53969, was, however, reported in Exxon patents, to be capable of C—C bond cleavage as well and therefore its ability to perform desulfurization without loss of fuel value is questionable. 

In the field of enzyme catalysis, heme-proteins such as cytochrome P450, for example, exhibit both types of 0-0 bond cleavages in organic hydroperoxides and peroxy acids (178). Heterolytic cleavage of HOOH/ROOH yields H20 or the corresponding alcohol, ROH and a ferryl-oxo intermediate (Scheme 4). Homolytic 0-0 bond cleavage results in the formation of a hydroxyl (HO ) or an alkoxyl (RO ) radical and an iron-bound hydroxyl radical. 

As mentioned earlier, by far the largest number of zinc enzymes are involved in hydrolytic reactions, frequently associated with peptide bond cleavage. Carboxypeptidases and ther-molysins are, respectively, exopeptidases, which remove amino acids from the carboxyl terminus of proteins, and endopeptidases, which cleave peptide bonds in the interior of a polypeptide chain. However, they both have almost identical active sites (Figure 12.4) with two His and one Glu ligands to the Zn2+. It appears that the Glu residue can be bound in a mono- or bi-dentate manner. The two classes of enzymes are expected to follow similar reaction mechanisms. 

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