Many spectrin mutations that destabilize tetramer formation and lead to hereditary hemolytic anemias are located at the N-terminal region of alpha-spectrin, with the Arg28 position considered to be a mutation hot spot. We have introduced mutations at positions 28 and 45 into a model peptide, Sp alpha 1-156, consisting of the first 156 residues in the N-terminal region of alpha-spectrin (alpha N...

To investigate the functional roles of individual HLA-DR residues in T cell recognition, transfectants expressing wild-type or mutant DR(alpha,beta 1*0401) molecules with single amino acid substitutions at 14 polymorphic positions of the DR beta 1*0401 chain or 19 positions of the DR alpha chain were used as antigen-presenting cells for five T cell clones specific for the influenza hemagglutini...

The crystal structure of a complex containing the engrailed homeodomain and a duplex DNA site has been determined at 2.8 A resolution and refined to a crystallographic R factor of 24.4%. In this complex, two separate regions of the 61 amino acid polypeptide contact a TAAT subsite. An N-terminal arm fits into the minor groove, and the side chains of Arg-3 and Arg-5 make contacts near the 5' end ...

To investigate the role of helix formation in the folding of protein L, a 62 residue alpha/beta protein, we studied the consequences of both single and multiple mutations in the helix on the kinetics of folding. A triple mutant with 11 additional carbon atoms in core residues in the amino-terminal portion of the helix folded substantially faster than wild type, suggesting that hydrophobic assoc...

In this paper, we define X-slant helix in Euclidean 3-space and we obtain helix, slant helix, clad and g-clad helix as special case of the X-slant helix. Then we study Darboux, tangential darboux developable surfaces and their singular points. Especially we show that the striction lines of these surfaces are singular locus of the surfaces.

KIT receptor kinase activity is repressed, prior to stem cell factor binding, by unknown structural constraints. Using site-directed mutagenesis, we examined the role of KIT intracellular juxtamembrane residues Met-552 through Ile-563 in controlling receptor autophosphorylation. Alanine substitution for Tyr-553, Trp-557, Val-559, or Val-560, all sitting along the hydrophobic side of an amphipat...

Alpha-helix based protein networks as they appear in intermediate filaments in the cell's cytoskeleton and the nuclear membrane robustly withstand large deformation of up to several hundred percent strain, despite the presence of structural imperfections or flaws. This performance is not achieved by most synthetic materials, which typically fail at much smaller deformation and show a great sens...

Prion diseases are associated with the conversion of the alpha-helix rich prion protein (PrPC) into a beta-structure-rich insoluble conformer (PrPSc) that is thought to be infectious. The mechanism for the PrPC-->PrPSc conversion and its relationship with the pathological effects of prion diseases are poorly understood, partly because of our limited knowledge of the structure of PrPSc. In parti...

The complete assignment of the proton NMR spectra of the homologous gamma 1-hordothionin and gamma 1-purothionin (47 amino acids, 4 disulfide bridges) from barley and wheat, respectively, has been performed by two-dimensional sequence-specific methods. A total of 299 proton-proton distance constraints for gamma 1-H and 285 for gamma 1-P derived from NOESY spectra have been used to calculate the...

Coiled-coil proteins consisting of multiple copies helices take part in transmembrane transportation and oligomerization, are used for drug delivery. Cross-alpha amyloid-like coiled-coil structures, which tens short align perpendicular to the fibril axis, often resist molecular replacement due uncertainty position each helix. Eight structures already solved posted protein data bank reconstructe...