Skip to main content

Table 2 Examples of amino acid side-chain specific chemistries

From: Combinatorial peptidomics: a generic approach for protein expression profiling

Reagents

Group specificity

Crossreactivity

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

 

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

 

p nitrophenylsulphenyl chloride

Trp, Cys

 

α Haloacetyl compounds

Met at pH3; also Cys, His, Tyr

NH2 groups (slow at low pH)