OGlcNAcylation and phosphorylation are the major competing intracellular post-translational modifications of serine and threonine residues. The structural effects of both post-translational modifications on serine and threonine were examined within Baldwin model α-helical peptides (Ac-AKAAAAKAAAAKAAGY-NH2 or Ac-YGAKAAAAKAAAAKAA-NH2). At the N-terminus of an α-helix, both phosphorylation and OGl...

Antifreeze glycoproteins (AFGPs) are able to bind ice, halt its growth, and the most potent inhibitors of ice recrystallization known. The structural basis for AFGP’s unique properties remains largely elusive. Here we determined antifreeze activities AFGP variants that constructed by chemically modifying hydroxyl groups disaccharide natural AFGPs. Using nuclear magnetic resonance, two-dimension...

To explain the requirement for anaerobic conditions in the induction of biodegradative L-threonine dehydratase in Escherichia coli, Crookes strain, measurements of cyclic AMP (cAMP) were made during aerobic and anaerobic growth and upon an aerobic-to-anaerobic transition. Internal cAMP levels were similar (5 to 10 muM) throughout exponential growth, whether aerobic or anaerobic, but only during...

Two auxotrophic mutants of Escherichia coli have been shown to accumulate significant amounts of l-threonine in the culture medium. One mutant, 13071, is deficient in alpha,epsilon-diaminopimelic acid (DAP), and the other, 13070, is deficient in both DAP and methionine. Accumulation of l-threonine by 13071 in a synthetic medium with mannitol as the carbon source at 37 C incubation temperature w...

Comprehensive studies were made with Lemna paucicostata Hegelm. 6746 of the effects of combinations of lysine, methionine, and threonine on growth rates, soluble amino acid contents, aspartokinase activities, and fluxes of 4-carbon moieties from aspartate through the aspartokinase step into the amino acids of the aspartate family. These studies show that flux in vitro through the aspartokinase ...

In addition to threonine auxotrophy, mutation of the Saccharomyces cerevisiae threonine biosynthetic genes THR1 (encoding homoserine kinase) and THR4 (encoding threonine synthase) results in a plethora of other phenotypes. We investigated the basis for these other phenotypes and found that they are dependent on the toxic biosynthetic intermediate homoserine. Moreover, homoserine is also toxic f...

Ginseng is one of famous herbs, which has many medical functions, such as neuroprotective effects, and anticancer function, because ginseng contains many active substances, and threonine is one important ingredient. In this study, to establish a mathematical model of uncertainty assessment for Threonine content in Ginseng by the amino acid assay, the sources of uncertainty in the measurement pr...

The work reported herein describes the results of endeavors to isolate and characterize the enzymes involved in the dehydrative deamination of the /?-hydroxyamino acids, serine and threonine. Preparations have been obtained which act on threonine and serine separately. L-Threonine dehydrase and L-serine dehydrase were separated by controlled heat denaturation and subsequent ammonium sulfate fra...