5‐Isothiocyanato‐1‐naphthalene Azide and p‐Azidophenylisothiocyanate

Abstract

Two hydrophobic, heterobifunctional azidoarylisothiocyanates have been synthesized. The reagents are applicable for group‐directed modification of membrane‐integrated protein segments and subsequent photo‐ induced cross‐linking with neighbouring membrane constituents. Both 5‐isothiocyanato‐I‐naphthalene azide and p‐azidophenylisothiocyanate are chemically characterized with respect to structure and photosensitivity. The reagents compete for the documented phenylisothiocyanate binding site(s) in bacteriorhodopsin and to the anion‐exchange protein (band 3) of human erythrocytes. Photoactivation of azidoarylisothiocyanate‐labeled membrane proteins leads to homopolymers when cross‐linked in purple membranes or in vesicles enriched in the anion‐exchange protein.

Oligomeric structure and the anion transport function of human erythrocyte band 3 protein

“…The photoactivated reagent DNCO, acting on isolated membranes, can cross-link band 3 almost completely to dimers, with no formation of higher oligomers [53]. Another photoactivated agent, p-azidophenylisothiocyanate, also crosslinks band 3 to dimers in membrane vesicles depleted of protein other than band 3 [ 131 ].…”

The Chemistry of Thiophosgene

“…The latter may be converted to N-isothiocyanatoamines (207) by heating 382 -384 (Scheme 57). Unlike the dialkylhydrazines (205), reaction of N,N-diphenylhydrazine (208) with thiophosgene does not yield N-isothiocyanatodiphenylamine (209) 380 as the final product. The latter is generated in situ and rapidly rearranges at higher temperatures to give 2-thiocyanatodiphenylamine (210) 385 Reaction of methylhydrazinium sulphate (211a) with thiophosgene gives two major products, 5,5-thiocarbonyldithiobis(3-methyl-2-oxo-2,3-dihydro-1 ,3 ,4-thiadiazole) (212a) and the corresponding 2-thioxo derivative (212b) which may be obtained by treating 5-mercapto-3-methyl-2-oxo-2,3-dihydro-1,3,4-thiadiazole (213a) and 213b, respectively, with thiophosgene.…”

A novel proteinaceous photolinker for simultaneous binding to an inert surface and a biomolecule

“…Advantage of using a protein molecule as a base includes a large number of functional groups available in a single molecule for formation of covalent linkages to incorporate several molecules of a photolinker. Sigrist and co-workers has immobilized biomolecules on inert surfaces in presence of light using such type of linker prepared by the reaction of BSA and 3-(trifluoro methyl)-3-(m-isothiocyanophenyl) diazirine [10][11][12]. However, this method is not popularized due to tedious and time consuming multistep procedure for preparation of such linking agent.…”