Proton Magnetic Resonance Studies of 4-(2-Pyridylazo)resorcinol (PAR) and Its Cobalt(III) Complexes

Proton nuclear magnetic resonance studies of isonitrile-heme protein complexes.

Steric interactions between bound ligand molecules and the valine E11 methyl groups of human hemoglobin and sperm whale myoglobin have been examined directly by high resolution NMR techniques. The methyl proton resonances of this amino acid are shifted markedly upfield and away from the bulk of the protein resonances by the shielding effect of circulating pi electrons in the porphyrin ring. We ...

Proton magnetic resonance studies of flavoquinone-metal complexes.

Fluorescence and Proton Nuclear Magnetic Resonance Studies of Thallous Ions - Crown Ether Complexes in Organic Solvents

Photochemistry, Fluorescence, Crown Ethers, Biology The complexing of thallous ions (T1+), with the crown ether dibenzo 18 crown-6 polyether (DB) has been studied by NMR, fluorescence, and pulse radiolysis techniques. NMR data show a strong interaction of the T1+ ions with the aromatic moieties. This is also illustrated by a static quenching of the aromatic fluorescence by Tl+. The rates of rea...

Electron paramagnetic resonance and proton relaxation rate studies of spin-labeled creatine kinase and its complexes.

A spin-labeled derivative of rabbit muscle creatine kinase has been prepared by reaction of the essential sulfhydryl group at the active sites with a stoichiometric amount of the nitroxide radical N-( I-oxyl-2,2,5,5-tetramethyl-d-pyrrolidinyl) iodoacetamide. The spin-labeled enzyme retains the ability to bind nucleotide substrates although it lacks the phosphotransferase and ATPase activities o...

Carbon-13 magnetic resonance evaluation of polypeptide secondary structure and correlation with proton magnetic resonance studies.

With the use of appropriately chosen solvent pairs it is demonstrated that solvent dependence of peptide carbonyl carbon resonances can be correlated with polypeptide secondary structure. Solvent titrations show the peptide carbonyl which is intramolecularly hydrogen bonded to exhibit less chemical shift on going from a dimethylsulfoxide solution to a solution containing a solvent which is a go...