temporary banners

 



 

Journal Issue - Volume 4 Issue 4 (April 1995)

Abstract General principles of protein structure, stability, and folding kinetics have recently been explored in computer simulations of simple exact lattice models. These models represent protein chains at a rudimentary level, but they involve few parameters, approximations, or implicit biases, and they allow complete explorations of conformational and sequence spaces. Such simulations have resulted in testable predictions that are...

Abstract The stability of a 15‐residue peptide has been investigated using CD spectroscopy and molecular simulation techniques. The sequence of the peptide was designed to include key features that are known to stabilize α‐helices, including ion pairs, helix dipole capping, peptide bond capping, and aromatic interactions. The degree of helicity has been determined experimentally by CD in three solvents (aqueous buffer, methanol, and...

Abstract Most serpins are inhibitors of serine proteinases and are thought to undergo a conformational change upon complex formation with proteinase that involves partial insertion of the reactive center loop into a β‐sheet of the inhibitor. Ovalbumin, although a serpin, is not an inhibitor of serine proteinases. It has been proposed that this deficiency arises from the presence of a charged residue, arginine, at a critical point...

Abstract Sites are microenvironments within a biomolecular structure, distinguished by their structural or functional role. A site can be defined by a three‐dimensional location and a local neighborhood around this location in which the structure or function exists. We have developed a computer system to facilitate structural analysis (both qualitative and quantitative) of biomolecular sites. Our system automatically examines the...

Abstract Staphylococcal nuclease A exists in two folded forms that differ in the isomerization state of the Lys 116‐Pro 117 peptide bond. The dominant form (90% occupancy) adopts a cis peptide bond, which is observed in the crystal structure. NMR studies show that the relatively small difference in free energy between the cis and trans forms (δDLGcis‐trans ≈ 1.2 kcal/mol) results from large and nearly compensating differences in enthalpy and...

Abstract Human interferon‐α8 (HuIFNα8), a type I interferon (IFN), is a cytokine belonging to the hematopoietic super‐family that includes human growth hormone (HGH). Recent data identified two human type I IFN receptor components. One component (p40) was purified from human urine by its ability to bind to immobilized type I IFN. A second receptor component (IFNAR), consisting of two cytokine receptor‐like domains (D200 and D200′),...

Abstract The paramagnetic relaxation reagent, 4‐hydroxy‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxy (HyTEMPO), was used to probe the surface exposure of methionine residues of recombinant cardiac troponin C (cTnC) in the absence and presence of Ca2+ at the regulatory site (site II), as well as in the presence of the troponin I inhibitory peptide (cTnIp). Methyl resonances of the 10 Met residues of cTnC were chosen as spectral probes because they are...

Abstract Farnesyl‐protein transferase (FPTase) catalyzes the posttranslational farnesylation of the cysteine residue located in the carboxyl‐terminal tetrapeptide of the Ras oncoprotein. Prenylation of this residue is essential for the membrane association and cell‐transforming activities of ras. Inhibitors of FPTase have been demonstrated to inhibit ras‐dependent cell transformation and thus represent a potential therapeutic strategy for the...

Abstract Rhizopuspepsin and other fungal aspartic proteinases are distinct from the mammalian enzymes in that they are able to cleave substrates with lysine in the P1 position. Sequence and structural comparisons suggest that two aspartic acid residues, Asp 30 and Asp 77 (pig pepsin numbering), may be responsible for generating this unique specificity. Asp 30 and Asp 77 were changed to the corresponding residues in porcine pepsin,...

Abstract The fasciculins are a family of closely related peptides that are isolated from the venom of mambas and exert their toxic action by inhibiting acetylcholinesterase (AChE). Fasciculins belong to the structural family of three‐fingered toxins from Elapidae snake venoms, which include the α‐neurotoxins that block the nicotinic acetylcholine receptor and the cardiotoxins that interact with ceil membranes. The features unique to...

Abstract Ferricytochrome c can be converted to the partially folded A‐state at pH 2.2 in the presence of 1.5 M NaCl. The structure of the A‐state has been studied in comparison with the native and unfolded states, using resonance Raman spectroscopy with visible and ultraviolet excitation wavelengths. Spectra obtained with 200 nm excitation show a decrease in amide II intensity consistent with loss of structure for the 50s and 70s...

Abstract The POU‐homeodomain (POUH) forms the bipartite DNA‐binding POD domain in association with the POU‐specific domain. The 1H, 15N, and 13C magnetic resonances of the 67‐amino acid long POUH of mouse Oct‐3 have almost completely been assigned, mainly through the combined use of three‐dimensional triple resonance NMR methods. Based on the distance and dihedral angle constraints derived from the NMR data, the solution structure of the POUH...

Abstract The locations of disulfide bonds and free cysteines in the heavy and light chains of recombinant human factor VIII were determined by sequence analysis of fragments produced by chemical and enzymatic digestions. The A1 and A2 domains of the heavy chain and the A3 domain of the light chain contain one free cysteine and two disulfide bonds, whereas the C1 and C2 domains of the light chain have one disulfide bond and no free...

Abstract The X‐ray structure analysis of a crystal of pig pancreatic α‐amylase (PPA, EC 3.2.1.1.) that was soaked with the substrate maltopentaose showed electron density corresponding to two independent carbohydrate recognition sites on the surface of the molecule. Both binding sites are distinct from the active site described in detail in our previous high‐resolution study of a complex between PPA and a carbohydrate inhibitor...

Abstract Saposin C is a sphingolipid activator protein of 8.5 kDa that activates lysosomal glucocerebrosidase. Previously, we synthesized and characterized a synthetic full‐length human saposin C protein that displays 85% of the activity of the native saposin C. In this study we use shorter synthetic peptides derived from the saposin C sequence to map binding and activation sites. By determining the activity and kinetic constant...

Page:   1 2 Next