The base pair lifetimes and apparent dissociation constants of a 21 base DNA hairpin and an analog possessing a disulfide cross-link bridging the 3'- and 5'-terminal bases were determined by measuring imino proton exchange rates as a function of exchange catalyst concentration and temperature. A comparison of the lifetimes and apparent dissociation constants for corresponding base pairs of the ...

: 1h nmr spectra of a series of enaminones r-co-ch=c(nhch2ph)-r  [1, r=ch3; 2, r=c6h5; 3, r=cf3; 4, r=ch2ch2ch2; 5, r=ch2c(ch3)2ch2], were obtained in the presence of trifluoroacetic acid in cdcl3 or dmso-d6 at 28 °c. steric, solvent, electronic and hydrogen bonding effects on the rates of acid-catalyzed nh proton exchanges were investigated. rate constants were calculated by 1h nmr line shape ...

The endochitinase from barley is the archetypal enzyme for a large class of plant-derived antifungal chitinases. The X-ray structure was solved previously in our laboratory and a mechanism of action proposed based on structural considerations. In this manuscript we report the use of a defined soluble substrate, 4-methylumbelliferyl beta-N,N',N"-triacetylchitotrioside, to characterize kinetic pa...

Calculation of the pA2 value and dissociation constants for an antagonist from the effects observed on isolated smooth muscles can be done in two ways: using Schild's plot procedure or Schild's equation. In our study we used the effects of muscarinic antagonists observed in experiments on isolated human and feline stomach and rat gastric fundus. Only the estimates of pA2 values and dissociation...

1. The binding of cholic acid to 10000Og supernatants from rat livers was investigated by equilibrium dialysis and gel-exclusion chromatography. 2. Supernatants were found to contain at least two classes of binding site for cholic acid. 3. These receptor molecules are probably proteins since incubation with proteolytic enzymes resulted in complete loss of cholic acid binding. 4. Supernatants we...