temporary banners

 



 

Journal Issue - Volume 6 Issue 2 (February 1997)

Abstract The covalent binding of complement components C3 and C4 is critical for their activities. This reaction is made possible by the presence of an internal thioester in the native protein. Upon activation, which involves a conformational change initiated by the cleavage of a single peptide bond, the thioester becomes available to react with molecules with nucleophilic groups. This description is probably sufficient to account...

Abstract Cutinase from Fusarium solani is a lipolytic enzyme that hydrolyses triglycerides efficiently. All the inhibited forms of lipolytic enzymes described so far are based on the use of small organophosphate and organophosphonate inhibitors, which bear little resemblance to a natural triglyceride substrate. In this article we describe the crystal structure of cutinase covalently inhibited by...

Abstract Recent advances in gene sequencing and rational drug design have re‐emphasized the need for new methods for protein analysis, classification, and structure and function prediction. In this article, we introduce a new method for analyzing protein sequences based on Sammon's non‐linear mapping algorithm. When applied to a family of homologous sequences, the method is able to capture the essential features of the similarity...

Abstract Three‐dimensional solution structures for three engineered, synthetic CBDs (Y5A, Y31A, and Y32A) of cellobiohydrolase I (CBHI) from Trichoderma reesei were studied with nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopy. According to CD measurements the antiparallel β‐sheet structure of the CBD fold was preserved in all engineered peptides. The three‐dimensional NMR‐based structures of Y31A and Y32A...

Abstract The assignment of the side‐chain NMR resonances and the determination of the three‐dimensional solution structure of the C10S mutant of enzyme IIBcellobiose (IIBcel) of the phosphoenolpyruvate‐dependent phosphotransferase system of Escherichia coli are presented. The side‐chain resonances were assigned nearly completely using a variety of mostly heteronuclear NMR experiments, including HCCH‐TOCSY, HCCH‐COSY, and COCCH‐TOCSY experiments...

Abstract Oxidative crosslinking of cysteines introduced by site‐specific mutagenesis is a powerful tool for structural analysis of proteins, but the approach has been limited to studies in vitro. We recently reported that intact cells of Escherichia coli could be treated with Cu(II)‐(o‐phenanthroline)3 or molecular iodine in a way that left unperturbed flagellar function or general chemotactic response, yet crosslinks were quantitatively formed...

Abstract Calbindin D9k is a small, well‐studied calcium‐binding protein consisting of two helix‐loop‐helix motifs called EF‐hands. The P43MG2 mutant is one of a series of mutants designed to sequentially lengthen the largely unstructured tether region between the two EF‐hands (F36‐S44). A lower calcium affinity for P43MG was expected on the basis of simple entropie arguments. However, this is not the case and P43MG (‐97 kJ‐mol−1) has a stronger...

Abstract A histidine residue with a PKα of 7 has been inferred to act as a general acid‐base catalyst for the reaction of creatine kinase (CK), catalyzing the reversible phosphorylation of creatine by ATP. The chicken sarcomeric muscle mitochon‐drial isoenzyme Mib‐CK contains several histidine residues that are conserved throughout the family of creatine kinases. By X‐ray crystal structure analysis, three of them (His 61, His 92, and His 186)...

Abstract We describe the insertion of an iron‐sulfur center into a designed four α‐helix model protein. The model protein was re‐engineered by introducing four cysteine ligands required for the coordination of the mulinucleate cluster into positions in the main‐chain directly analogous to the domain predicted to ligand the interpeptide [4Fe‐4S (S‐cys)4] cluster, Fx, from PsaA and PsaB of the Photosystem I reaction center. This was achieved by...

Abstract To gain insight into the free energy changes accompanying protein hydrophobic core formation, we have used computer simulations to study the formation of small clusters of nonpolar solutes in water. A barrier to association is observed at the largest solute separation that does not allow substantial solvent penetration. The barrier reflects an effective increase in the size of the cavity occupied by the expanded but...

Abstract Structurally characterizing partially folded states is problematic given the nature of these transient species. A peptide 20mer, T38AQLIATLKNGRKISLDLQA57 (P20), which has been shown to partially fold in a relatively stable turn/loop conformation (LKNGR) and transient β‐sheet structure, is a good model for studying backbone and side‐chain mobilities in a transiently folded peptide by using l3C‐NMR relaxation. Here, four residues in P20,...

Abstract The intestinal fatty acid binding protein is one of a class of proteins that are primarily β‐sheet and contain a large interior cavity into which ligands bind. A highly conserved region of the protein exists between two adjacent antiparallel strands (denoted as D and E in the structure) that are not within hydrogen bonding distance. A series of single, double, and triple mutations have been constructed in the turn between...

Abstract This paper explores the dependence of the molecular dynamics (MD) trajectory of a protein molecule on the titration state assigned to the molecule. Four 100‐ps MD trajectories of bovine pancreatic trypsin inhibitor (BPTI) were generated, starting from two different structures, each of which was held in two different charge states. The two starting structures were the X‐ray crystal structure and one of the solution...

Abstract Human glutaredoxin is a member of the glutaredoxin family, which is characterized by a glutathione binding site and a redox‐active dithiol/disulfide in the active site. Unlike Escherichia coli glutaredoxin‐1, this protein has additional cysteine residues that have been suggested to play a regulatory role in its activity. Human glutaredoxin (106 amino acid residues, Mr = 12,000) has been purified from a pET expression vector with both...

Abstract A novel methodology is described for the assignment of disulfide bonds in proteins of known sequence. The denatured protein is subjected to limited reduction by tris(2‐carboxyethyl)phosphine (TCEP) in pH 3.0 citrate buffer to produce a mixture of partially reduced protein isomers; the nascent sulfhydryls are immediately cyanylated by l‐cyano‐4‐dimethylamino‐pyridinium tetrafluoroborate (CDAP) under the same buffered...

Page:   1 2 3 Next