IndraLab
Statements
sparser
"The data were subsequently group fit with a common exchange rate for residues that satisfy χ 2 group /χ 2 invididual < 2.0. xref Group fitting yielded k ex = 4954 ± 82 s −1 for p-DUBA ( xref ). np-DUBA undergoes a similar conformational exchange process with the exchange rate of 5750 ± 110 s −1 ( xref )."
sparser
"Motions in the apo state of enzymes can facilitate substrate binding by enabling transitions into to a binding competent state xref , xref and can also regulate the catalytic cycle by allowing access to conformational states conducive for catalytic turnover. xref – xref The low activity of np-DUBA likely results from its inability to form a highly productive enzyme-substrate complex rather than low binding affinity to substrates because only 3-fold enhancement in the affinity to the fluorogenic ubiquitin-7-amino-4-methylcoumarin (Ub-AMC) substrate was observed upon phosphorylation, whereas the enhancement in k cat is 300-fold. xref We can speculate that an important feature of the productive enzyme-substrate complex is that the α1 helix can adopt a closed conformation, as defined by the crystal structure of p-DUBA in the ubiquitin-bound state. xref The only conformer in np-DUBA lies between the a and b conformers in terms of structural characteristics according to the relative positions of cross-peaks. xref This observation indicates that at least in the free state, the α1 helix in np-DUBA adopts a more open conformation than the a conformer in p-DUBA."
sparser
"Broadening of NMR spectral lines and the resulting low signal intensities are signatures of conformational exchanges on the μs-ms scales. xref Among ~ 120 cross-peaks detectable in the 15 N TROSY spectra of p-DUBA, many display broad 1 H lines, whereas the 15 N transverse relaxation rates of majority of the resonances are consistent with the molecular weight. xref , xref TROSY spectra of nonphosphorylated DUBA (np-DUBA) display similar features."