Lysine maleylation

Acetylation of Plant Proteins. Acetic and succinic anhydrides have been the most common derivatives used for the modification of plant proteins and under the conditions employed the e-NH2 of lysine is the principal site of acylation (Fig. 1). These derivatives are relatively stable requiring strongly acidic conditions for hydrolysis compared to the maleyl derivatives which are acid labile (10). 

Fig. 2 Chemical structure of SMANCS, Two chains of SMA [copoly(styrene-maleyl-butylate-half-n-ester)] are attached to the N-terminal amino group of alanine 1 and the e-amino group of lysine 20 of NCS...

The half-life (x) of e-N-maleyl lysine is 11 h at pH 3.5 and 37 °C. More rapid cleavage is observed with the 2-methyl-maleyl derivative (x < 3 min at pH 3.5 and 20 °C) and the 2,2,3,3-tetrafluoro-succinyl derivative (x very low at pH 9.5 and 0°C). Cysteine binds maleic anhydride through an addition reaction. The S-succinyl derivative is quite stable. This side reaction is, however, avoided when protein derivatization is done with exo-cis-3,6-end-oxo-l,2,3,6- tetrahydrophthalic acid anhydride ... 

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