Incubation of the exocellular DD-carboxypeptidase/transpeptidase of Streptomyces R61 with phenylglyoxal resulted in a time-dependent decrease in the enzyme activity. This inactivation was demonstrated to be due to modification of the Arg-99 side chain. In consequence, the role of that residue was investigated by site-directed mutagenesis. Mutation of Arg-99 into leucine appeared to be highly de...

Several mutants of tobacco mosaic virus that contain additional lysine residues as a result of mutations in the coat protein were investigated. Mutant E66 has a lysine residue replacing asparagine at position 140 when compared with the wild-type vulgare and this lysine residue reacts readily in the intact virus with methyl picolinimidate. Mutant B13a has two new lysine residues in the coat prot...

Saccharopine dehydrogenase (EC 1.5.1.7) from bakers’ yeast was reversibly inactivated by pyridoxal and pyridoxal 5’-phosphate. The inactivation by pyridoxal 5’-phosphate was accompanied by the appearance of a peak at 428 nm, which was shifted to 325 nm upon reduction with NaBH4. Paper chromatography of an acid hydrolysate of the pyridoxal 5’-phosphate-treated, NaBH4-reduced enzyme showed the pr...

EF-P is a bacterial tRNA-mimic protein, which accelerates the ribosome-catalyzed polymerization of poly-prolines. In Escherichia coli, EF-P is post-translationally modified on a conserved lysine residue. The post-translational modification is performed in a two-step reaction involving the addition of a β-lysine moiety and the subsequent hydroxylation, catalyzed by PoxA and YfcM, respectively. T...

Some preliminary proposals as to the mode of amine substrate attachment to acyl intermediates of guinea pig liver transglutaminase and human blood coagulation factor XIIIa were formulated from substrate and inhibitor studies (Gross, M., Whetzel, N. K., and Folk, J. E. (1977) J. Biol. Chem. 252, 3752-3759). The present data supply more concrete explanations for the stereopreference toward peptid...

The PTEN tumor suppressor is frequently affected in cancer cells, and inherited PTEN mutation causes cancer-susceptibility conditions such as Cowden syndrome. PTEN acts as a plasma-membrane lipid-phosphatase antagonizing the phosphoinositide 3-kinase/AKT cell survival pathway. However, PTEN is also found in cell nuclei, but mechanism, function, and relevance of nuclear localization remain uncle...

The Fos and Jun family of transcription factors contain an invariant sequence motif lysine-cysteine-arginine (KCR) in the highly conserved DNA-binding region. Reduction of the cysteine residue is necessary to facilitate DNA-binding. Here, we examined the potential dual roles of the flanking lysine and arginine residues in influencing the redox reactivity of the cysteine and the DNA-binding acti...