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Examples of amino acid side-chain specific chemistries |
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| Reagents |
Group specificity |
Crossreactivity |
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| α Haloacetyl compounds: Iodoacetate; α haloacetamides; bromotrifluoroacetone; N chloroacetyliodotyramine |
Cys, His, Met, Tyr |
NH2 groups (slow at low pH) |
| N Maleimide derivatives: N ethylmaleimide (at pH < = 7) |
Cys |
NH2 groups (slow at low pH) |
| Mercurial compounds (most specific): p chloromercuribenzoate(PCMB)/p hydroxymercuribenzoate(PHMB) in H2O (optimum at pH 5, competitive displacement possible) |
Cys |
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| Disulphide reagents (reversible): 5,5 dithiobis (2 nitrobenzoic acid) (DTNB); 4,4 dithiodipyridine; methyl 3 nitro 2 pyridyl disulphide; methyl 2 pyridyl disulphide |
Cys |
|
| N acetylimidazole |
Tyr |
NH2 groups (slow) |
| Diazonium compounds (optimum at pH9, unstable) |
Tyr, His |
NH2, Trp, Cys and Arg (slow) |
| Dicarbonyl compounds (pH > = 7): glyoxal; phenylglyoxal; 2,3 butanedione; 1,2 cyclohexanedione |
Arg |
Lys at pH < = 7 |
| p toluenesulphonylphenyl alaninechloromethyl ketone (TPCK); p toluenesulphonyllysine chloromethyl ketone (TLCK); Methyl-p-nitrobenzenesulphonate |
His |
Cys |
| Diethylpyrocarbonate (reversible at pH > = 7) |
His (at pH4) |
NH2 |
| 2 hydroxy 5 nitrobenzyl bromide (HNBB) |
Trp |
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| p nitrophenylsulphenyl chloride |
Trp, Cys |
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| α Haloacetyl compounds |
Met at pH3; also Cys, His, Tyr |
NH2 groups (slow at low pH) |
Soloviev et al. Journal of Nanobiotechnology 2003 1:4 doi:10.1186/1477-3155-1-4 |
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