Enzymic cleavage

Vitamins are classified by their solubiUty characteristics iato fat-soluble and water-soluble groups. The fat-soluble vitamins A, E, and K result from the isoprenoid biosynthetic pathway. Vitamin A is derived by enzymic cleavage of the symmetrical C q beta-carotene, also known as pro-vitamin A. Vitamins E and K result from condensations of phytyldiphosphate (C2q) with aromatic components derived from shikimic acid. Vitamin D results from photochemical ring opening of 7-dehydrocholesterol, itself derived from squalene (C q). 

Esterase enzymes - cleavage of various ester bonds to yield an ackf and an alcohol, ie R1COOR2 + H2O <---------------------------> RiCOOH + R2OH... 

Nielsen P.E., Egholm M., Berg R. H., Buchardt O. Sequence specific inhibition of DNA restriction enzyme cleavage by PNA. Nucleic Acids Res. 1993 21 197-200. 

One of the major reasons for studying the ESR of this series of Co(II)-corrinoids is that this spectral tool may give information on the mechanism of corrin-dependent enzymes. Cleavage of the Co—C—cr-bond has been studied in a few enzymes by using Co(II) ESR, and there is evidence... 

It is clear that both intact cell MALDI-TOF and PFGE have their limitations. PFGE analyses probes the chromosomal DNA of microorganisms for variations in the locations of specific restriction enzyme cleavage sites, while MALDI-TOF mass spectrometry of intact cells primarily examines abundant proteins such as ribosomal proteins35 and those associated with or near bacterial cell walls.58 In order for MALDI-TOF to detect a variation, a mutation must lead to noticeable changes in the expression of cell wall—associated... 

There is as yet no known enzyme that breaks the C—F bond in fluoroacetic acid, FCH2COOH, or in related compounds. It is interesting to note, however, that in the course of our investigations2 on peroxidase-catalysed oxidations, we have effected an enzymic cleavage of the C—F bond in p-fluoroaniline.3 In acetate buffer (pH 4-5) and at room temperature, the amine was oxidized by hydrogen peroxide and peroxidase to give mainly the red crystalline 2-amino-5-p-fluoroanilinobenzoquinone di-p-fluoroanil (XX). 

It is believed that the oxidation of p-fluoroaniline is the first recorded case of an enzymic cleavage of a C—F bond. 

Fig. 5. Structures of Cy5.5-labelled poly(ethylene glycol) poly-(L-lysine) graft polymers 10 and 11. Arrows indicate the enzyme cleavage sites. Published with permission from Weissleder et al. [68,69]...

C-terminal residue not related to enzyme cleavage sites... 

The AT-terminal amino acid can be ascertained by the Sanger method. Enzymic cleavage using either chymotrypsin or trypsin will break the peptide into smaller fragments. The fragments obtained will be different, depending on the enzyme and its specificity. The smaller fragments are then each sequenced by the Edman technique. C-Terminal residues in the smaller... 

The full paper of Tietze s biogenetic-type synthesis of secologanin aglucone methyl ether and sweroside aglucone methyl ether has been published (Vol. 5, p. 18), and a second paper independently reports in full the rapid enzymic cleavage of secologanin to the bicyclic hemiacetal previously described by R. T. Brown (Vol. 7, p. 27) longer reaction times result in the formation of (146). ... 

Hydrolysis of mt/o-inositol l(3),2-cyclic phosphate under acidic or alkaline conditions affords a mixture of myo-inositol l(3)-phosphate and myo-inositol 2-phosphate, with the former preponderating.275 As the cyclic phosphate may be prepared275 from the 2-phosphate, which is itself readily obtained from myo-inositol hexaphosphate by enzymic cleavage,268,276 and as the l(3)-phosphate may be isolated277 from the hydrolysis mixture, the reaction sequence provides a convenient way... 

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