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A study of NMR (super 15)N chemical shifts based on ab initio quantum mechanical calculations carried out on a minimalist model system linking both Ca(super 2+) binding sites across the beta-sheet of an EF-hand domain is discussed. The study is based on the structural comparison of the closed and open states of an alpha-spectrin EF-hand domain.

Research has been conducted on the globular proteins' reversible folding-unfolding processes. The study of these processes carried out via the use of the (super)15 N-selective isotopic labeling to simplify 2D (super)1 H -(super)15 N HSQC spectra and to minimize unfolded state signal overlap is presented.

Results show that hamster galectin-3 exists as a monomer in solution and the N-terminal domain interacts with the C-terminal carbohydrate-recognition domain. Data suggest that oligomerization of galectin through terminal interactions, upon absorption to substratum, is consistent with the observed lectin binding to immobilized lamin.

Research describes the effects of a point mutation at position 8 of calcium-binding site IV of calmodulin V136G, which reveal the nature of the amino acid residues involved in the calcium-induced folding process. Nuclear magnetic resonance data indicate that intradomain cooperativity and interaction between domains occur during calcium binding reactions.

Ligand carboxylate group interactions with arginine residues in complexes of Lactobacillus casei dihydrofolate reductase with substrate analogues and substrates have been studied using NMR. The study was to investigate the structures and dynamics of the Arg 57 guanidino interactions with ligand carboxylate groups in complexes of DHFR with the substrate folate and its fragment, PABG. The carboxylate group binds to the enzyme in a way like that in a parent molecule such as methotrexate or folate.

The binding of dihydrofolate reductase to the drug trimethoprim and its cofactor NADPH result in a decrease in ring-flipping around the trimethoxybenzyl ring of the drug. This occurs because the nicotinamide ring of NADPH is situated close to the trimethoxybenzyl ring.

Nuclear magnetic resonance experiments were conducted using (super 15)N- labeled and (super 1)H-labeled Lactobacillus casei dihydrofolate reductase (DHFR). Analysis of the complexes formed by L. casei with the analogues of the antibacterial drug brodimoprim was conducted, while interactions between carboxylate groups on the ligands and basic residues in the protein were monitored. Results measuring (super 1)H and (super 15)N chemical shift perturbations provide evidence about the interactions involving Arg57 with the 4-carboxylate and 4,6-dicarboxylate brodimoprim analogues.

Research was conducted to determine the high-resolution solution structure for the minimal B-Myb DNA-binding domain, B-MybR2R3. Another objective was to characterize the specific complex formed with a synthetic DNA fragment corresponding to the Myb target site on the Myb-regulated gene tom-1. Results suggest that R2 and R3 from B-Myb have different tertiary structures despite significant sequence similarities. Findings also indicate that there are extensive contacts between B-MybR2R3 and its DNA target site.

A study was conducted to examine 15N-shielding changes resulting from the Ca2+ coordination of the O(7)=C(7)-N(8) amido group and to analyze the use of the amido nitrogen atom perturbation as a probe of site-specific Ca2+ occupation in calmodulin and other proteins. A Varian 500 spectrometer was utilized to determine the heteronuclear single quantum coherence spectra. Results showed that the 15N shieldings were sensitive to various intra and intermolecular interactions.

Matrix metalloproteinases (MMPs) are in the zinc endopeptidase family responsible for extracellular matrix catabolism. Four tissue inhibitors of metalloproteinases (TIMPs) have been identified, and both MMPs and TIMPs conisist of distinct funcational domains. Changes in the NMR chemical shift of backbone amide nuclei were used to map the MMP binding site on the N-terminal domain of TIMP-2.

The preparation of Lactobacillus casei dihydrofolate reductase bearing biosynthetically incorporated (2S,4S)-5-fluoroleucine ([5-F]-Leu DHFR) is described. Its spectra was obtained using 1H and 19F nuclear magnetic resonance. ([5-F]-Leu DHFR)'s 19F spectrum showed 12 reasonably sharp peaks for the 13 leucine residues in DHFR. The broad range of chemical shift of 15 ppm is attributed solely to electrostatic field effects due to local charge fields. Side-chain conformational differences between different leucine residues are believed to also have an effect.

The structure of a brodimoprim analogue in its complex with Lactobacillus casei dihydrofolate reductase is determined by using a ligand docking method based on nuclear Overhauser effect (NOE) distance constraints and by making the protein residues close to the ligand more flexible. Intermolecular and intramolecular proton-proton NOEs between protons on the ligand and on the protein have been measured to provide distance constraints. The asymmetrically substituted benzyl ring of the ligand binds in a single conformation.

Two- and three-dimensional 1H NMR experiments help assign sequence-specific 1H resonance for 123 of the 127 amino acid residues in the active domain of the truncated form of tissue inhibitors of metalloproteinases-2 (Delta-TIMP-2). Study of nuclear Overhauser effect data helps arrive at the secondary structure of the domain and a low-resolution tertiary structure defining the protein backbone configuration. A comparative study of the structure of Delta-TIMP-2 with that of other protein fold families suggests that the Delta-TIMP-2 structure is homologous to the proteins of the oligosaccharide/oligonucleotide binding fold family.

Anti-human immunodeficiency virus type 1 (HIV-1) function of chemically altered heparins depends on the correlation of HIV-1 activity inhibition and the binding of gp120 to the V3 loop in the in vitro region. Selective O-desulfation, negative density and N-desulfation markedly reduce the pathological activity of HIV-1. The V3 loop-gp120 binding site is confirmed as the anti-HIV-1 activity site of heparin.