Figure 5

Acetaldehyde-induced deactivation of BSL-B depends on the number of modifiable amino acid residues and on the presence of primary amino compounds in the solvent. To investigate the influence protein-bound primary amino groups (N-terminus and ε-amino groups) as well free glycine on the deactivation process, BSL-B (1 mg/mL) has (1) been incubated with (+) or without (-) metylacetimidate; (2) then transferred (+) into fresh glycine/NaOH-buffer (10 mM, pH 10) or not (-); and (3) incubated with (+) or without (-) 500 mM acetaldehyde for 24 h. Subsequently, all samples have been analyzed with SDS-PAGE (A) and IEF (B). Furthermore, the residual hydrolytic activity (C) and the colour (D) of all samples containing acetaldehyde have been documented. S: SDS-PAGE and IEF-Standard. 1: - methylacetimidate, - glycine/NaOH-buffer, - acetaldehyde. 2: + methyl-acetimidate, - glycine/NaOH-buffer, -acetaldehyde. 3: - methylacetimidate, - glycine/NaOH-buffer, + acetaldehyde. 4: + methyl-acetimidate, - glycine/NaOH-buffer, + acetaldehyde. 5: + methylacetimidate, + glycine/NaOH-buffer, + acetaldehyde.