Disulfides, cleavage

Atomic orbital basis sets containing diffuse functions must be used at least for the atoms onto which the electron will attach. This means the sulfur atoms if one is studying disulfide cleavage and the O, C, and N atoms (at the site of cleavage) if one is studying N-Ca cleavage. It is important to then check to... 

Thiadiazole, formation, 312, 313, 445 Thiazole formation bromoester, 298-304 bromoketone, 565 Thiazolidinone formation beta lactam, disulfide cleavage, 552 nitrile addition, 301 Thiehopyridine formation, 586 Thienothiazinol formation, 593 Thioacetal formation, 130, 185, 248 glyoxylate, 355 ethyl mercaptopropionate, 447 Thioacid formation, thioformamidoyl chloride, 184... 

Disulfide cleavage reactions. Prior to sequence analysis inter- and intrachain disulfide linkages are irreversibly cleaved by one of the two procedures shown. 

Bisulfite addition to pyrimidines Disulfide cleavage Sulfite oxidation Sulfite reduction... 

An interesting disulfide cleavage is performed with 7,7/-dithio-bis[l,3,6-trimethyllumazine] (276) in basic medium yielding the relatively stable silver 7-sulfenate (277) and thiol (278) (Scheme 44). The free 1,3-dimethyllumazine-7-sulfenic acid (279) has been prepared from 7-isopropylthio and 7-[2-(4-nitrophenyl)ethylthio]-l,3-dimethyllumazine first by oxidation to the corresponding sulfoxides (282, 283) then by a modified Cope elimination and dbu treatment, respectively (Scheme 44). 

Volk M, Kholodenko Y, Lu HSM, Gooding EA, DeGrado WF, Hochstrasser RM. Peptide conformational dynamics and vibrational Stark effects following photoinitiated disulfide cleavage. J Phys Chem B 1997 101 8607-8616. 

SHORT-LIVED INTERMEDIATE) HYDROPHOBIC, IONIC, H2 DISULFIDE CLEAVAGE FOLLOWED BY UNFOLDING AND HYDROPHOBIC BONDING... 

It is clear from these studies that rotatory dispersion, especially if it is supplemented by hydrodynamic techniques, provides more accurate information on conformational changes than do monochromatic rotations. In any case, the changes in monochromatic rotation caused by disulfide cleavage can always be anticipated and perhaps in many cases eliminated by calculation, as Turner et al. (1958) and Wiirz and Haurowitz (1961) have been able to do. 

The denaturation of 3-lactoglobulin by nonpolar agents and the conformational effects of disulfide cleavage upon serum albumin and ribonu-clease demonstrate that sources of stability in addition to helical segments may be required for the rigid compact shape of globular proteins. A number of further studies upon the respective contributions of secondary and tertiary structure to this stability may be selected to illustrate the role that optical rotation, used as a method solely for determining secondary structure, can play in conjunction with other methods of structural assessment. 

Zincke disulfide cleavage. Formation of sul-fenyl halides by three essentially similar methods involving the action of chlorine or bromine on aryl disulfides, thiophenols, or arylbenzyl sulfides. 

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