Role of Long-Range Protein Dynamics in Different Thymidylate Synthase Catalyzed Reactions

Recent studies of Escherichia coli thymidylate synthase (ecTSase) showed that a highly conserved residue, Y209, that is located 8 Å away from the reaction site, plays a key role in the protein’s dynamics. Those crystallographic studies indicated that Y209W mutant is a structurally identical but dynamically altered relative to the wild type (WT) enzyme, and that its turnover catalytic rate governed by a slow hydride-transfer has been affected. The most challenging test of an examination of a fast chemical conversion that precedes the rate-limiting step has been achieved here. The physical nature of both fast and slow C-H bond activations have been compared between the WT and mutant by means of observed and intrinsic kinetic isotope effects (KIEs) and their temperature dependence. The findings indicate that the proton abstraction step has not been altered as much as the hydride transfer step. Additionally, the comparison indicated that other kinetic steps in the TSase catalyzed reaction were substantially affected, including the order of the substrate binding. Enigmatically, although Y209 is H-bonded to 3''-OH of 2''-deoxyuridine-5''-mono­phosphate (dUMP), its altered dynamics is more pronounced on the binding of the remote cofactor, (6R)-N⁵,N¹⁰-methylene-5,6,7,8-tetrahydrofolate (CH₂H₄folate), revealing the importance of long-range dynamics of the enzymatic complex and its catalytic function.     

Effects of the self-directed search on high school students.

Compared the effects on 959 high school students of the Self-Directed Search (SDS), a self-administered vocational counseling simulation; the Vocational Preference Inventory (VPI); and no treatment. Students taking the SDS or the VPI evaluated the instruments as moderately positive, reported feeling more satisfied with their current occupational choice, and were considering more occupational alternatives than the control group both the day after the experiment and 3 wks later. Students taking the SDS selected occupations most consistent with their personality traits and reported less need to see a counselor immediately. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The location of hydrogen in the kinetics of oxidation of ferrous alloys by superheated steam

The rate of emission of hydrogen from the metal surface and from the oxide surface has been determined during the oxidation of ferrous alloys at 501°C. The kinetics were in accordance with the assumption of a parabolic rate law, and the rate constants were in agreement with those calculated from the thickness of the oxide layer at the end of the reaction. The proportion of hydrogen emitted from the metal to that from the oxide surface showed a dependence on the partial pressure of steam for the 9%Cr-1%Mo alloy at 501°C. The ratio was dependent on the alloy composition, and also on temperature, as shown by results for the 9%Cr-1%Mo alloy at 450 and 552°C. For this alloy, the activation energy and rate constants are consistent with a rate-determining step dependent on cation diffusion. The oxide film is almost impermeable to hydrogen gas. A possible oxidation mechanism is suggested.     

Deriving Efficient Porous Heteroatom‐Doped Carbon Electrocatalysts for Hydrazine Oxidation from Transition Metal Ions‐Coordinated Casein

In this work, the synthesis of high‐performance, metal ion‐imprinted, mesoporous carbon electrocatalysts for hydrazine oxidation reaction (HzOR) using casein or a family of phosphoproteins derived from cow's milk as a precursor is shown. The synthesis is made possible by mixing trace amounts of non‐noble metal ions (Fe³⁺ or Co²⁺) with casein and then producing different metal ions‐functionalized casein intermediates, which upon carbonization, followed by acid treatment, lead to metal ion‐imprinted catalytically active sites on the materials. The materials effectively electrocatalyze HzOR with low overpotentials at neutral pH and exhibit among the highest electrocatalytic performances ever reported for carbon catalysts. Their catalytic activities are also better than the corresponding control material, synthesized by carbonization of pure casein and other materials previously reported for HzOR. This work demonstrates a novel synthetic route that transforms an inexpensive protein to highly active carbon‐based electrocatalysts by modifying its surfaces with trace amounts of non‐noble metals. The types of metal ions employed in the synthesis are found to dictate the electrocatalytic activities of the materials. Notably, Fe³⁺ is found to be more effective than Co²⁺ in helping the conversion of casein into more electrocatalytically active carbon materials for HzOR.     

Determination of the uncertainty for the thermal conductivity obtained as a function of the moisture content for several foodstuffs

Many times, when an experimental result is communicated, the uncertainty is omitted, particularly in the case in which the parameter of interest is determined by curve fitting. This article presents a review study to include an uncertainty to the parameter of interest, obtained by fitting of a straight line to an experimental data set, supposing that systematic errors can be neglected. This study is applied to the determination of expressions for the thermal conductivity of food products, supposing a constant mean temperature. In this case, in general, the thermal conductivity is a linear function of the moisture content (wb). Expressions of the thermal conductivity were obtained for several foodstuffs, according to the recommendation of the International Organization for Standardization. Thus, for a given moisture content, the obtained expressions enable to determine the value for the thermal conductivity, as well as its uncertainty, for a stipulated confidence limit.     

Thermoregulatory and cardiovascular responses to creatine, glycerol and alpha lipoic acid in trained cyclists

Background

It has been shown that supplementation with creatine (Cr) and glycerol (Gly), when combined with glucose (Glu) necessary for the enhancement of Cr uptake by skeletal muscle, induces significant improvements in thermoregulatory and cardiovascular responses during exercise in the heat.

Purpose

To determine whether Cr/Gly-induced thermoregulatory and cardiovascular responses are maintained when the majority (~75%) of the Glu in the Cr/Gly supplement is replaced with the insulintropic agent alpha lipoic acid (Ala).

Methods

22 healthy endurance trained cyclists were randomly assigned to receive either 20?g/day (4?×?5?g/day) of Cr, 2?g ^.kg^-1 BM per day (4?×?0.5?g ^.kg^-1 BM per day) of Gly and 150?g/day (4?×?37.5?g/day) of Glu or 20?g/day (4?×?5?g/day) of Cr monohydrate, 2?g ^.kg^-1 BM per day (4?×?0.5?g ^.kg^-1 BM per day) of Gly (100?g/day (4?×?25?g/day) of Glu and 1000?mg/day (4?×?250?mg/day) of Ala for 7?days for 7?days. Exercise trials were conducted pre- and post-supplementation and involved 40?min of constant-load cycling exercise at 70% O₂ max by a self-paced 16.1?km time trial at 30°C and 70% relative humidity.

Results

Median and range values of TBW increased significantly by 2.1 (1.3-3.3) L and 1.8 (0.2-4.6) L in Cr/Gly/Glu and Cr/Gly/Glu/Ala groups respectively (P?=?0.03) and of BM not significantly by 1.8 (0.2-3.0) kg and 1.2 (0.5-2.1) kg in Cr/Gly/Glu and in Cr/Gly/Glu/Ala, respectively (P?=?0.75). During constant load exercise, heart rate (HR) and core temperature (Tcore) were significantly lower post-supplementation: HR was reduced on average by 3.3?±?2.1 beats/min and by 4.8?±?3.3 beats/min (mean ± SD) and Tcore by 0.2?±?0.1 (mean ± SD) in the Cr/Gly/Glu and Cr/Gly/Glu/Ala, respectively The reduction in HR and Tcore was not significantly different between the supplementation groups.

Conclusions

In comparison to the established hyper hydrating Cr/Gly/Glu supplement, supplement containing Cr/Gly/Ala and decreased amount of Glu provides equal improvements in thermoregulatory and cardiovascular responses during exercise in the heat.     

Reply to Baron and Stampfl's "A note on 'long-distance ESP: A controlled study.' "

Concurs with the belief of A. Baron and T. Stampfl (see pa, vol. 47:issue 5) that quantitative data have not, and probably will never, give "convincing evidence" for esp. Therefore, in these studies the qualitative data, from which perhaps can be learned the laws governing telepathic transmission, are of primary interest. Such knowledge can conceivably improve the present poor signal-noise ratio, thereby making telepathy demonstrable under controlled laboratory conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)