Beyond binding change: the molecular mechanism of ATP hydrolysis by F1-ATPase and its biochemical consequences

F1-ATPase is a universal multisubunit enzyme and the smallest-known motor that, fueled by the process of ATP hydrolysis, rotates in 120o steps. A central question is how the elementary chemical steps occurring in the three catalytic sites are coupled to the mechanical rotation. Here, we performed cold chase promotion experiments and measured the rates and extents of hydrolysis of preloaded bound ATP and promoter ATP bound in the catalytic sites. We found that rotation was caused by the electrostatic free energy change associated with the ATP cleavage reaction followed by Pi release. The combination of these two processes occurs sequentially in two different catalytic sites on the enzyme, thereby driving the two rotational sub-steps of the 120o rotation. The mechanistic implications of this finding are discussed based on the overall energy balance of the system. General principles of free energy transduction are formulated, and their important physical and biochemical consequences are analyzed. In particular, how exactly ATP performs useful external work in biomolecular systems is discussed. A molecular mechanism of steady-state, trisite ATP hydrolysis by F1-ATPase, consistent with physical laws and principles and the consolidated body of available biochemical information, is developed. Taken together with previous results, this mechanism essentially completes the coupling scheme. Discrete snapshots seen in high-resolution X-ray structures are assigned to specific intermediate stages in the 120o hydrolysis cycle, and reasons for the necessity of these conformations are readily understood. The major roles played by the “minor” subunits of ATP synthase in enabling physiological energy coupling and catalysis, first predicted by Nath's torsional mechanism of energy transduction and ATP synthesis 25 years ago, are now revealed with great clarity. The working of nine-stepped (bMF1, hMF1), six-stepped (TF1, EF1), and three-stepped (PdF1) F1 motors and of the α3β3γ subcomplex of F1 is explained by the same unified mechanism without invoking additional assumptions or postulating different mechanochemical coupling schemes. Some novel predictions of the unified theory on the mode of action of F1 inhibitors, such as sodium azide, of great pharmaceutical importance, and on more exotic artificial or hybrid/chimera F1 motors have been made and analyzed mathematically. The detailed ATP hydrolysis cycle for the enzyme as a whole is shown to provide a biochemical basis for a theory of “unisite” and steady-state multisite catalysis by F1-ATPase that had remained elusive for a very long time. The theory is supported by a probability-based calculation of enzyme species distributions and analysis of catalytic site occupancies by Mg-nucleotides and the activity of F1-ATPase. A new concept of energy coupling in ATP synthesis/hydrolysis based on fundamental ligand substitution chemistry has been advanced, which offers a deeper understanding, elucidates enzyme activation and catalysis in a better way, and provides a unified molecular explanation of elementary chemical events occurring at enzyme catalytic sites. As such, these developments take us beyond binding change mechanisms of ATP synthesis/hydrolysis proposed for oxidative phosphorylation and photophosphorylation in bioenergetics

Soaking Effects on Physical Characteristics of Basmati (Pusa Basmati 1121) Rice

PB1121 paddy was soaked in water at seven different temperatures (40-80oC) till it achieved desired moisture. Soaking showed significant effect on physical characteristics of PB1121 rice. Soaking altered the length, breadth, thickness volume, surface area, equivalent diameter and sphericity of of paddy grain. Un-soaked grains had bulk and true density as 508.60 and 1138.8 kg/m3, respectively whereas that of soaked grains varied from 511-527 and 1188-1238 kg/m3, respectively. HRY of un-soaked rice was 42.12% whereas that of soaked rice varied from 50.21-53.05%. Soaked grains were harder than the un-soaked grains. Un-soaked rice had lightness and redness values as 60.26 and 6.47, respectively but, with soaking temperature, lightness decreased (9.56-16.23%) whereas redness increased (9.58-25.50%). Soaking imparted reddish color to the grain, but not yellowness. Based on grain color, hardness and HRY, it was inferred that 65 to 70oC temperatures would be appropriate for soaking of PB1121 paddy

Nitinol shape memory alloy spring

Manufacturing, over the years, has evolved through three revolutions brought out by the impact of mechanization, electricity and Information Technology. The update in manufacturing has its root of intelligence. Necessity of miniaturization is shifted the use of conventional actuators with smart actuators. Conventional actuators generally produce the power in proportion to their volume, which reduce their application in micro applications. A concise review of the recent developments within nearly ten years on shape memory alloys has been presented. Besides other available shape memory alloys, Nitinol(Ni-Ti) is preferred due to its array of characteristicslike light weight, high power to weight ratio, noiseless operation, ease of actuation and muscle like movement. Shape memory effect and pseudo-elasticity play a crucial role in smart materials. Various actuation modes (Joule heating, hot water, laser assisted) and cooling methods are tabulated for Ni-Ti. The different forms of Nitinolare commercially available, but spring is used specially, due to its coiled structure

Minimum and Maximum Limit to Number of Myosin II Motors Participating in an Ensemble Motility

Extensive research on centrifugal compressors has been planned to define diffuser stall limits for a group of stages characterized by low blade-outlet-width-to-impeller-radius-ratio. Very little data is available on this centrifugal compressor family, especially for the last stage configuration. In addition, the most important stall diffuser prediction criteria barely cover this machine type. Many experimental tests have been planned to investigate several geometry variations. A simulated stage with a backward channel upstream, a 2D impeller with a vaneless diffuser and a constant cross section volute downstream constitute the basic geometry. Several diffuser geometries with different widths, pinch shapes, diffusion ratios were tested. Test results and conclusions are shown in the paper in terms of critical diffuser inlet flow angles, flow coefficients at stall inception and stage working ranges. The main task of the present work is to increase the knowledge and the amount of available data to characterize rotating stall phenomena, in particular for very narrow stages

Plant protection measures to promote organic farming in Nepal: prospects and challenges

Organic farming is a production system that relies on ecosystem management rather than external agricultural inputs to sustain the health of soils, ecosystem and organisms. This needs enough organic plant protection measures and biological fertilizers by eliminating synthetic pesticides and fertilizers. An attempt was made to review current plant protection measures for organic farming in Nepal. Though some insect pests and diseases are very hard to control without the use of chemical pesticides, this is high time to produce agriculture products organically. There is ample prospect of organic production in Nepal utilizing traditional knowledge of Nepalese farmers and existing agri-biodiversity. The paper is focused on best utilization of local natural resources, indigenous knowledge and bio-control agents for plant protection in organic agriculture. The information related to organic plant protection measures are collected from various sources and are grouped. The authors have listed technologies on organic plant protection measures in Nepal and made some suggestions to improve the organic farming of the country

Nitinol shape memory alloy spring

446-453Manufacturing, over the years, has evolved through three revolutions brought out by the impact of mechanization, electricity and Information Technology. The update in manufacturing has its root of intelligence. Necessity of miniaturization is shifted the use of conventional actuators with smart actuators. Conventional actuators generally produce the power in proportion to their volume, which reduce their application in micro applications. A concise review of the recent developments within nearly ten years on shape memory alloys has been presented. Besides other available shape memory alloys, Nitinol(Ni-Ti) is preferred due to its array of characteristicslike light weight, high power to weight ratio, noiseless operation, ease of actuation and muscle like movement. Shape memory effect and pseudo-elasticity play a crucial role in smart materials. Various actuation modes (Joule heating, hot water, laser assisted) and cooling methods are tabulated for Ni-Ti. The different forms of Nitinolare commercially available, but spring is used specially, due to its coiled structure