temporary banners

 



 

Journal Issue - Volume 8 Issue 2 (1999)

Abstract The hypersensitivity resistance response directed by the N' gene in Nicotiana sylvestris is elicited by the tobacco mosaic virus (TMV) coat protein R46G, but not by the U1 wild‐type TMV coat protein. In this study, the structural and hydrodynamic properties of R46G and wild‐type coat proteins were compared for variations that may explain N' gene elicitation. Circular dichroism spectroscopy reveals no significant secondary or tertiary...

Abstract The usefulness of molecular dynamics to assess the structural integrity of mutants containing several mutations has been investigated. Our goal was to determine whether molecular dynamics would be able to discriminate mutants of a protein having a close–to–wild‐type fold, from those that are not folded under the same conditions. We used as a model the B1 domain of protein G in which we replaced the unique central α‐helix by...

Abstract Cathepsin K is a lysosomal cysteine protease belonging to the papain superfamily. It has been implicated as a major mediator of osteoclastic bone resorption. Wild‐type human procathepsin K has been crystallized in a glycosylated and a deglycosylated form. The latter crystals diffract better, to 3.2 å resolution, and contain four molecules in the asymmetric unit. The structure was solved by molecular replacement and refined...

Abstract Fructose 1,6‐bisphosphate aldolase catalyzes the reversible cleavage of fructose 1,6‐bisphosphate and fructose 1‐phosphate to dihydroxyacetone phosphate and either glyceraldehyde 3‐phosphate or glyceraldehyde, respectively. Catalysis involves the formation of a Schiff's base intermediate formed at the ϵ‐amino group of Lys229. The existing apo‐enzyme structure was refined using the crystallographic free‐R‐factor and maximum...

Abstract The crystal structure of the FMN‐binding domain of human NADPH‐cytochrome P450 reductase (P450R‐FMN), a key component in the cytochrome P450 monooxygenase system, has been determined to 1.93 å resolution and shown to be very similar both to the global fold in solution (Barsukov I et al., 1997, J Biomol NMR 10:63–75) and to the corresponding domain in the 2.6 å crystal structure of intact rat P450R (Wang M et al., 1997, Proc Nat Acad...

Abstract The biotin carboxyl carrier protein (BCCP) is a subunit of acetyl‐CoA carboxylase, a biotin‐dependent enzyme that catalyzes the first committed step of fatty acid biosynthesis. In its functional cycle, this protein engages in heterologous protein–protein interactions with three distinct partners, depending on its state of post‐translational modification. Apo‐BCCP interacts specifically with the biotin holoenzyme synthetase,...

Abstract Hydrophobic substitutions at solvent‐exposed positions in two α‐helical regions of the bacteriophage P22 Arc repressor were introduced by combinatorial mutagenesis. In helix A, hydrophobic residues were tolerated individually at each of the five positions examined, but multiple substitutions were poorly tolerated as shown by the finding that mutants with more than two additional hydrophobic residues were biologically...

Abstract A statistical analysis of a representative data set of 169 known protein structures was used to analyze the specificity of residue interactions between spatial neighboring strands in β‐sheets. Pairwise potentials were derived from the frequency of residue pairs in nearest contact, second nearest and third nearest contacts across neighboring β‐strands compared to the expected frequency of residue pairs in a random model. A...

Abstract Hsp70 molecular chaperones contain three distinct structural domains, a 44 kDa N‐terminal ATPase domain, a 17 kDa peptide‐binding domain, and a 10 kDa C‐terminal domain. The ATPase and peptide binding domains are conserved in sequence and are functionally well characterized. The function of the 10 kDa variable C‐terminal domain is less well understood. We have characterized the secondary structure and dynamics of the...

Abstract Haloalkane dehalogenase (DhlA) hydrolyzes short‐chain haloalkanes to produce the corresponding alcohols and halide ions. Release of the halide ion from the active‐site cavity can proceed via a two‐step and a three‐step route, which both contain slow enzyme isomerization steps. Thermodynamic analysis of bromide binding and release showed that the slow unimolecular isomerization steps in the three‐step bromide export route...

Abstract We examine the similarities and differences between two widely used knowledge‐based potentials, which are expressed as contact matrices (consisting of 210 elements) that gives a scale for interaction energies between the naturally occurring amino acid residues. These are the Miyazawa–Jernigan contact interaction matrix M and the potential matrix S derived by Skolnick J et al., 1997, Protein Sci 6:676–688. Although the correlation...

Abstract A simple approach to estimate the number of α‐helical and β‐strand segments from protein circular dichroism spectra is described. The α‐helix and β‐sheet conformations in globular protein structures, assigned by DSSP and STRIDE algorithms, were divided into regular and distorted fractions by considering a certain number of terminal residues in a given α‐helix or β‐strand segment to be distorted. The resulting secondary...

Abstract Unfolded apocytochrome c acquires an α‐helical conformation upon interaction with lipid. Folding kinetic results below and above the lipid's CMC, together with energy transfer measurements of lipid bound states, and salt‐induced compact states in solution, show that the folding transition of apocytochrome c from the unfolded state in solution to a lipid‐inserted helical conformation proceeds via a collapsed intermediate state ...

Abstract Thermotoga maritima (Tm) expresses a 7 kDa monomeric protein whose 18 N‐terminal amino acids show 81% identity to N‐terminal sequences of cold shock proteins (Csps) from Bacillus caldolyticus and Bacillus stearothermophilus. There were only trace amounts of the protein in Thermotoga cells grown at 80°C. Therefore, to perform physicochemical experiments, the gene was cloned in Escherichia coli. A DNA probe was produced by PCR from genomic Tm DNA...

Abstract β‐Lactamases are responsible for bacterial resistance to β‐lactams and are thus of major clinical importance. However, the identity of the general base involved in their mechanism of action is still unclear. Two candidate residues, Glu166 and Lys73, have been proposed to fulfill this role. Previous studies support the proposal that Glu166 acts during the deacylation, but there is no consensus on the possible role of this...

Page:   1 2 Next