Structural redesign and stabilization of the overlapping tandem beta-turns of RNA polymerase II

Peptides representing single repeat units of the carboxy-terminal domain (CTD) of RNA polymerase II (Tyr-Ser-Pro-Thr-Ser-Pro-Ser-Tyr-NH2, 1) contain overlapping Ser-Pro-Xaa-Xaa beta-turn forming sites which permit their overall structure to closely resemble members of the quinoxaline class of antitumor DNA bisintercalators. We have modified this native sequence at the i+2 positions of each beta-turn unit by substituting Gly or D-Ala in an attempt to preorganize this structure in aqueous solution. CD and NMR spectroscopic investigations confirmed the presence of type II beta-turns within each of the substituted peptides in contrast to the native sequence which contains a relatively low population of turn structure. In addition, an examination of singly substituted peptides suggests that an increase in the population of beta-turn structure within the amino-terminal Ser-Pro-Xaa-Xaa site also increased the formation of beta-turn structure in the carboxy-terminal (unmodified) Ser-Pro-Xaa-Xaa site; in comparison, substitution in the carboxy-terminal site did not influence structure in the remaining portion of the peptide. Overall, these results suggest that the structures formed could provide unique, preorganized linkers for the construction of novel DNA-interactive bisintercalators.     

Contrasting roles for symmetrically disposed beta-turns in the folding of a small protein

To investigate the role of turns in protein folding, we have characterized the effects of combinatorial and site-directed mutations in the two beta-turns of peptostreptococcal protein L on folding thermodynamics and kinetics. Sequences of folded variants recovered from combinatorial libraries using a phase display selection method were considerably more variable in the second turn than in the first turn. These combinatorial mutants as well as strategically placed point mutants in the two turns had a similar range of thermodynamic stabilities, but strikingly different folding kinetics. A glycine to alanine substitution in the second beta-turn increased the rate of unfolding more than tenfold but had little effect on the rate of folding, while mutation of a symmetrically disposed glycine residue in the first turn had little effect on unfolding but slowed the rate of folding nearly tenfold. These results demonstrate that the role of beta-turns in protein folding is strongly context-dependent, and suggests that the first turn is formed and the second turn disrupted in the folding transition state.     

Conformational interconversions in peptide beta-turns: analysis of turns in proteins and computational estimates of barriers

The two most important beta-turn features in peptides and proteins are the type I and type II turns, which differ mainly in the orientation of the central peptide unit. Facile conformational interconversion is possible, in principle, by a flip of the central peptide unit. Homologous crystal structures afford an opportunity to structurally characterize both possible conformational states, thus allowing identification of sites that are potentially stereochemically mobile. A representative data set of 250 high-resolution (相似文献   

Prediction of mandibular autorotation

PURPOSE: The purpose of this investigation was to test the hypothesis that the mandible rotates around the same point during maxillary impaction surgery as during initial jaw opening. This point, called the center of mandibular autorotation (CAR), could then be used to predict mandibular position and to decide whether only maxillary impaction would be needed to correct the occlusion and the facial profile. PATIENTS AND METHODS: Preoperatively, two lateral cephalograms were obtained from a consecutive series of 20 patients who underwent maxillary impaction without concomitant mandibular ramus osteotomy. One cephalogram was taken with the mandible in centric relation using a wax bite wafer and another with a jaw opening of 10 mm using a fabricated acrylic bite block with the mandible manipulated to its most retruded position. The CAR was calculated before and after jaw opening using the Rouleaux method on the lower incisor and gonion point. A third lateral cephalogram was taken within 2 days postoperatively. The postoperative lower incisal point was then transferred to the first cephalogram using cranial base superimposition. RESULTS: When the preoperative and postoperative distances between CAR and incisal point were compared, there was no significant difference between these distances, proving the hypothesis. CONCLUSIONS: The method used is a practical and precise way to determine the center of mandibular autorotation on an individual basis. The center of rotation during initial jaw opening is the same as during impaction surgery.     

Prediction of Salmonella mutagenicity

The use of glutaraldehyde as a fixative in bioprostheses and drug delivery matrices is reviewed. The chemistry of glutaraldehyde cross-linking and its effect on the biological performance of a number of bioprostheses such as tissue heart valves, vascular grafts, pericardial patches, tendon grafts and drug delivery matrices are examined.     

Prediction of airbone target detection

The visibility of a uniformly luminous object depends on the apparent contrast between the object and its background, the angular subtense of the object, the contrast threshold of the observer at the level of luminance to which the eyes are adapted, the conditions and technique of observing, and the shape of the object. Techniques for combining the influence of the various factors have been applied to the problem of predicting airborne target detectability. Recommendations for achieving the desired detectability are made.     

Prediction of Concerted Sediment Flushing

A proprietary one-dimensional numerical model was developed for predicting the amounts of sediment flushed and deposited in the reservoirs in series, the bed evolutions, and variations of the suspended solids concentrations along a river during the concerted sediment flushing events. The model consists of a flow movement module and sediment transport module in which the bed material load is taken as sediment mixture. The nonuniform property of the bed material load is modeled by the introduction of a mixing layer, transition layer, and deposition strata. The model was calibrated on the basis of the field data at Dashidaira and Unazuki reservoirs on the Kurobe River in Japan. The calculated results are in good agreement with the measurements. For the reservoirs out of Japan, the Ashida and Michiue bed load formula used in the model should be verified or replaced by other formulas.     

Prediction of attendant tenure.

MMPI L, K, Pd, and Ma subscales were administered to 109 persons who were subsequently hired for the position of cottage attendant in an insttution for the mentally retarded. 3 subscales and a composite score from all 4 of them distinguished significantly between attendants who were fired during the first 6 months of employment and attendants who were retained in employment and did not receive unfavorable evaluations from their immediate supervisors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prediction of Undrained Sinkhole Collapse

Sinkholes are surface depressions or shafts resulting from the collapse of a submerged cavity in soil. The cavities that lead to sinkholes form as a result of underlying geology in limestone areas, or as a result of human activity such as mining or leakage from a sewer. The formation of sinkholes is often sudden and can lead to extensive damage and loss of life, especially in urban areas. Much of the literature on the subject of sinkhole formation is empirical in nature, often being associated with specific locations. This paper presents the results of a study, using numerical modeling, of the undrained stability of the submerged cavities that lead to sinkhole formation. Finite-element limit analysis techniques (using programs developed at the University of Newcastle) are used to obtain upper and lower bound values of a suitable load parameter, which bracket the exact solution. The results are compared to analytical solutions, both from literature and derived independently.     

Prediction of powder coating porosity

Translated from Poroshkovaya Metallurgiya, No. 12, pp. 36–41, December, 1990.     

Prediction of foreign language proficiency.

Best predictors of overall proficiency in a foreign language were examined in 2 experiments. Experiment 1 involved 60 10th- and 11th-grade girls attending a private, single-sex high school; Experiment 2 involved a coeducational population of 36 10th-grade students in a public school. Best predictors in both experiments were end of 1st-year grade in the foreign language and a measure of phonology–orthography, foreign language word decoding. In 1 experiment, native language vocabulary skill was also a predictor of overall proficiency. Heretofore, foreign language grade and word decoding had not been considered as predictors of foreign language proficiency. The finding that foreign language word decoding was a good predictor of both oral and written proficiency suggests its importance as both a predictor variable and an important component of foreign language proficiency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prediction of scuba training performance.

296 trainees of the US Navy School for Divers Second Class completed a demographic questionnaire, a health inventory, and an attitude survey. Significant multiple correlations in a validation sample and in a cross-validation sample were obtained between these variables and a pass-fail performance criterion. Scales dealing with mental health and training apprehension were the most significant predictors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

江西北部大湖塘钨矿田成矿预测研究

大湖塘矿田位于江西北部九岭钨多金属成矿带中部,面积约200 km~2。本文以地质、物探、化探、遥感等地质找矿标志作为预测因子,运用综合找矿信息量、特征分析等数理统计方法进行成矿有利信息量、特征变量计算,认为石英脉(带)及燕山花岗岩是找矿的重要标志。利用MAPGIS平台,对网格单元找矿总信息量及关联度等值线进行了二次圈连。共圈定找矿可行地段2个,通过野外地质调查及钻孔验证,取得较好地质找矿效果,说明该预测方法对找矿具有一定的参考和指导意义。     

Prediction of psychiatric aide performance.

Two keys were developed for items on the California Psychological Inventory: one key for a sample of psychiatric aides divided into a short-tenure and a long-tenure subgroups, and the other key for a sample divided into two subgroups on a performance rating. Applying these keys to cross-validation samples, no relationship whatever was found between predictions and actual job tenure or performance rating. Possible reasons for the keys to fail to stand up are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prediction of transformation textures in steels

Both discrete and continuous mathematical formalisms are employed to simulate texture evolution during the γ-to-α transformation in steels. Five f.c.c. NiCo alloys with different stacking fault energies (SFE's) were previously cold rolled to four reductions (40, 70, 90 and 95%) and their textures characterized by the orientation distribution function (ODF) method. The corresponding b.c.c. transformation textures are calculated from these experimental textures according to three different orientation relationships. The ODF's derived from the Bain relation are much sharper than the ones deduced from the Kurdjumov-Sachs (KS) or the Nishiyama-Wassermann (NW) relations, although the general trends of the three families of textures are similar. Ferrite textures determined on controlled rolled steels, heavily deformed in the unrecrystallized γ region, agree reasonably well with the b.c.c. textures calculated, according to the KS relationship, from the NiCo alloy with similar SFE. The two major ferrite components, namely the {332} 〈113〉 and {113} 〈110〉, are shown to originate from the three main orientations of cold rolled f.c.c. material, i.e. the {112} 〈111〉 (Cu), {110} 〈112〉 (Bs) and {123} 〈634〉 (S). Such ferrite formation from heavily deformed austenite follows the KS relationship without any variant selection. By contrast, the texture of martensite produced from deformed austenite involves significant amounts of selection.