Abstract Structures of irinotecan (CPT-11) in neutral lactone, carboxyl, and anionic carboxylate forms singlet ground states their complexes with Cu(II) doublet are optimized using B3LYP/6-311G* treatment. Metal ion affinities (MIA), Cu charges Laplacians Cu-ligand bond critical points possible CPT active sites evaluated. The formation the ligand leads to release CO 2 that can cause a decrease ...

A theoretical study of the electronic structure of the photoactive yellow protein (PYP) model chromophore, para-coumaric acid (p-CA), is presented. Electronically excited states of the phenolate and carboxylate isomers of the deprotonated p-CA are characterized by high-level ab initio methods including state-specific and multistate multireference pertrubation theory (SS-CASPT2, and MS-CASPT2), ...

The effects of anchoring groups on electron injection from adsorbate to nanocrystalline thin films were investigated by comparing injection kinetics through carboxylate versus phosphonate groups to TiO2 and SnO2. In the first pair of molecules, Re(LA)(CO)3Cl (ReC1A) and Re(Lp)(CO)3Cl (ReC1P), [LA=2,2'-bipyridine-4,4'-bis-CH2-COOH, Lp=2,2'-bipyridine-4,4'-bis-CH2-PO3H2], the anchoring groups wer...

Based on localization and high activities of pyrroline-5-carboxylate reductase and proline dehydrogenase activities in soybean nodules, we previously suggested two major roles for pyrroline-5-carboxylate reductase in addition to the production of the considerable quantity of proline needed for biosynthesis; namely, transfer of energy to the location of biological N(2) fixation, and production o...

The organotin(IV) compounds, [Ph3SnL H]n Æ nCCl4 (1), [Me2SnL (OH2)] (2), [ Bu2SnL ] (3), [Ph2SnL ]n (4), [Ph3SnL H]n (5) and [Ph3SnL H]n (7) (L 1 = 2-{[(2Z)-(3-hydroxy-1-methyl-2-butenylidene)]amino}phenylpropionate and L 3 = 2-{[(E)-1-(2-hydroxyaryl)alkylidene]amino}phenylpropionate), were synthesized by treating the appropriate organotin(IV) chloride(s) with the potassium salt of the ligand ...

The C-peptide of ribonuclease A (residues 1 to 13) is obtained by cyanogen bromide cleavage at Met13, which converts methionine to a mixture of homoserine lactone (giving C-peptide lactone) and homoserine carboxylate (giving C-peptide carboxylate). The helix-forming properties of C-peptide lactone have been reported. The helix is formed intramolecularl$ in aqueous solution, is stabilized at’ lo...

Camptothecins are an important class of anti-cancer agents and under physiological conditions exist in equilibrium between the lactone and carboxylate forms. The lactone form of camptothecins is crucial for their anti-tumor effect. Camptothecins, especially carboxylate forms, bind strongly to the plasma protein, human serum albumin (HSA). This binding of the carboxylate form alters the hydrolys...

The speciation of Eu complexed with polyacrylic acid (PAA) and alumina-bound PAA (PAA(ads)) was studied at pH 5 in 0.1 M NaClO(4). Structural parameters were obtained from (7)F(0) -->(5)D(0) excitation spectra measured by laser-induced fluorescence spectroscopy as well as from Eu L(III)-edge extended X-ray absorption fine structure (EXAFS) spectra. The coordination mode was also investigated by...

Continuous wave (cw) X-band EPR spectra at approximately 90 K were obtained for iron-transferrin-anion complexes with 18 anions. Each anion had a carboxylate group and at least one other polar moiety. As the second polar group was varied from hydroxyl to carbonyl to amine to carboxylate, the EPR spectra changed from a dominant signal at g' approximately 4.3 with a second smaller peak at g' appr...

Equations that can be used for partition coefficients of both neutral molecules and ions have been revised, and the term that is specific to ions has been re-evaluated. A new method has been devised for the determination of partition coefficients from water to organic solvents for carboxylate anions that is based on the variation of pK(a) for carboxylic acids with solvent. Using these partition...