Binding sites of Torpedo acetylcholinesterase (EC 3.1.1.7) for quaternary ligands were investigated by x-ray crystallography and photoaffinity labeling. Crystal structures complexes with determined at 2.8-A resolution. In a complex edrophonium, nitrogen the ligand interacts indole Trp-84, its m-hydroxyl displays bifurcated hydrogen bonding to two members catalytic triad, Ser-200 His-440. tacrine, acridine is stacked against Trp-84. The bisquaternary decamethonium oriented along narrow gorge...

The identification of a novel mutation (E46K) in one the KTKEGV-type repeats amino-terminal region α-synuclein suggests that this and, more specifically, Glu residues may be important regulating ability to polymerize into amyloid fibrils. It was demonstrated E46K increased propensity fibrillize, but effect less than A53T mutation. substitution Glu46 for an Ala also assembly α-synuclein, polymers formed can have different ultrastructures, further indicating amino acid position has significant...

Alpha-synuclein (alpha-syn) is the major component of intracellular inclusions in several neurodegenerative diseases, and conversion soluble alpha-syn into filamentous aggregates may contribute to disease pathogenesis. Since mechanisms leading formation are unclear, vitro models aggregation yield insights this process. To that end, we examined consequences on progressive deletion carboxy-terminus regulating fibril formation, show here carboxy-terminal truncated proteins aggregate faster than...

The enzyme acetylcholinesterase generates a strong electrostatic field that can attract the cationic substrate acetylcholine to active site. However, long and narrow site gorge seems inconsistent with enzyme's high catalytic rate. A molecular dynamics simulation of in water reveals transient opening short channel, large enough pass molecule, through thin wall near tryptophan-84. This suggests substrate, products, or solvent could move this "back door," addition entrance revealed by...

Electrostatic calculations based on the recently solved crystal structure of acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) indicate that this enzyme has a strong electrostatic dipole. The dipole is aligned with gorge leading to its active site, so positively charged substrate will be drawn site by field. Within gorge, aromatic side chains appear shield from direct interaction most negatively residues give rise affinity quaternary ammonium compounds for rings, coupled...

The motion of water molecules close to amide groups causes their vibrational frequencies vary rapidly in time. These variations are uniquely sensed by 2-dimensional infrared spectroscopy (2D IR). Here, it is proposed from experiments on fibrils amyloid beta (Abeta)40 that there the fibrils. spatial locations (D(2)O) were inferred responses 18 modes Abeta40 labeled with (13)C = (18)O. Fast frequency found for residues L17 and V18 apposed L34 V36, suggesting cavities or channels containing...

Abstract The active site of acetylcholinesterase (AChE) from Torpedo californica is located 20 Å the enzyme surface at bottom a narrow gorge. To understand role this gorge in function AChE, we have studied simulations its molecular dynamics. When were conducted with pure water filling gorge, residues vicinity deviated quickly and markedly crystal structure. Further study original crystallographic data suggests that bis‐quaternary decamethonium (DECA) ion, acquired during purification,...

Vancomycin is one of the most important and commonly used antibiotics in hospitals. Despite numerous investigations, however, it not clear how vancomycin recognizes its site action bacterial cell wall. The increasing incidence resistance to makes imperative understand these recognition determinants so that alternative agents may be developed. Herein we report first crystal structure vancomycin. resolves a long-standing controversy about carboxylate by vancomycin, suggests possible...

The 2D IR spectra of the amide-I vibrations amyloid fibrils from Abeta40 were obtained. matured formed strands having isotopic substitution by (13)C (18)O at Gly-38, Gly-33, Gly-29, or Ala-21 show vibrational exciton reduced dimensionality. Indeed, linear chain excitons amide units are seen, for which interamide coupling is measured in grown 50% and 5% mixtures labeled unlabeled strands. data prove that 1D parallel in-register sheets. constants each indicated residues carbonyls chains...

Evidence of oxidative stress and the accumulation fibrillar amyloid beta proteins (Abeta) in senile plaques throughout cerebral cortex are consistent features pathology Alzheimer disease. To define a mechanistic link between these two processes, various aspects relationship lipid membrane damage amyloidogenesis were characterized by chemical physical techniques. Earlier studies this demonstrated that oxidatively damaged synthetic membranes promoted amyloidogenesis. The reported herein...

The fully developed lesion of Alzheimer's Disease is a dense plaque composed fibrillar amyloid β-proteins with characteristic and well-ordered β-sheet secondary structure. Because the incipient most likely develops when these proteins are first induced to form structure, it important understand factors that induce adopt this conformation. In investigation we used novel infrared spectroscopy can characterize conformation, orientation, rate accumulation protein on various lipid membranes...

The two main competing models for the structure of discoidal lipoprotein A-I complexes both presume that protein component is helical and situated around perimeter a lipid bilayer disc. However, more popular “picket fence” model orients helices perpendicular to surface bilayer, while alternative “belt” them parallel surface. To distinguish between these models, we have investigated human using novel form polarized internal reflection infrared spectroscopy can characterize relative...

ABSTRACT The ability of cecropin A to permeabilize and depolarize the membranes Escherichia coli ML-35p bacteria has been compared its bactericidal activity in an extension earlier studies performed on synthetic lipid vesicle (L. Silvestro, K. Gupta, J. H. Weiser, P. Axelsen, Biochemistry 36:11452–11460, 1997). Our results indicate that differences concentration dependences membrane permeabilization depolarization seen vesicles are not manifested whole bacteria. both phenomena roughly...

The N-acetylated hexapeptide WLLLLL (AcWL5) partitions into lipid membranes and is believed to assemble an antiparallel β-sheet. As a test of this structural assignment, the peptide bonds residues 2−6 were labeled with 13C allowed adsorb onto supported membrane. Peptides bound membrane examined for evidence coupling between vibrational modes in adjacent β-strands internal reflection infrared spectroscopy. Experimental results indicate that amide I absorption band D2O (i.e., I') attributable...

Senile plaques in the cerebral parenchyma are a pathognomonic feature of Alzheimer's disease (AD) and mainly composed aggregated fibrillar amyloid beta (Abeta) proteins. The associated with neuronal degeneration, lipid membrane abnormalities, chemical evidence oxidative stress. view that Abeta proteins cause these pathological changes has been challenged by suggestions they have protective function or merely byproducts process. This investigation was conducted to determine whether promote...

Buried water molecules in the structurally homologous family of eukaryotic serine proteases were examined to determine whether buried waters and their protein environments are conserved these proteins. We found 16 equivalent sites trypsin/ogen, chymotrypsin/ogen, elastase, kallikrein, thrombin, rat tonin mast cell protease, 5 additional enzymes which share primary specificity trypsin. Based on an alignment 30 protease sequences, it appears that 21 highly conserved. The comprised primarily...

Reverse micelles (RMs) made from water and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) are commonly studied experimentally as models of aqueous microenvironments. They small enough for individual RMs to also be by molecular dynamics (MD) simulation, which yields detailed insight into their structure properties. Although RM size is determined the loading ratio (i.e., molar AOT), experimental measurements imprecise inconsistent, problematic when seeking understand relationship between size,...

Polyunsaturated fatty acyl chains (PUFAs) concentrate in the brain and give rise to numerous oxidative chemical degradation products. It is widely assumed that these products are result of free radical chain reactions, reactions this type have been demonstrated preparations where a single PUFA substrate species predominates. However, it unclear whether such can occur biologically complex milieu lipid membranes substrates minority species, diverse scavengers or other quenching mechanisms...