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Judith Storch - One of the best experts on this subject based on the ideXlab platform.
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role of surface lysine residues of adipocyte fatty acid binding protein in fatty acid transfer to phospholipid vesicles
Biochemistry, 2001Co-Authors: Hengling Liou, Judith StorchAbstract:The tertiary structure of murine adipocyte fatty acid-binding protein (AFABP) is a flattened 10-stranded β-barrel capped by a helix−turn−helix segment. This helical domain is hypothesized to behave as a “lid” or portal for ligand entry into and exit from the binding cavity. Previously, we demonstrated that anthroyloxy-labeled fatty acid (AOFA) transfer from AFABP to phospholipid membranes occurs by a Collisional Process, in which ionic interactions between positively charged lysine residues on the protein surface and negatively charged phospholipid headgroups are involved. In the present study, the role of specific lysine residues located in the portal and other regions of AFABP was directly examined using site-directed mutagenesis. The results showed that isoleucine replacement for lysine in the portal region, including the αI- and αII-helices and the β C-D turn, resulted in much slower 2-(9-anthroyloxy)palmitate (2AP) transfer rates to acidic membranes than those of native AFABP. An additive effect was ...
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mechanism of free fatty acid transfer from rat heart fatty acid binding protein to phospholipid membranes evidence for a Collisional Process
Journal of Biological Chemistry, 1992Co-Authors: Hyunggu Kim, Judith StorchAbstract:Fatty acid binding proteins (FABP) are a family of low molecular weight proteins found in many tissues that actively utilize free fatty acids (ffa). FABP would be expected to have a particularly important role in the heart, where over 80% of energy requirements are derived from oxidation of long chain fatty acids. The precise physiological function of heart FABP (H-FABP) has not been definitively identified, although it is thought to play a role in intracellular ffa transport. To examine the possible role of H-FABP in cardiac myocyte transfer of ffa, we examined the transfer of fluorescent anthroyloxy ffa (AOffa) from H-FABP to model phospholipid membranes, using a resonance energy transfer assay. In contrast to previous observations of ffa transfer from liver FABP and from membranes, transfer from H-FABP to membranes appears to occur by a different mechanism. AO-palmitate (16:0) transfer was 1.5-fold slower than AO-stearate (18:0) transfer, and mono-unsaturation did not affect the transfer rate. The AOffa transfer rate from H-FABP increased with increasing ionic strength and decreased slightly between pH 7 and 9. These results suggest that the rate of ffa transfer from H-FABP to membranes is independent of the ffa aqueous solubility. Thermodynamic analysis showed that the free energy of activation for the ffa transfer Process arises primarily from an enthalpic component, with only a small entropic contribution, again suggesting the lack of an aqueous phase route of ffa delivery. Finally, the ffa transfer rate was found to be directly dependent on the concentration of acceptor membranes. These data therefore suggest that transfer of AOffa from H-FABP to membranes may occur via Collisional interactions between the protein and membranes.
Jikai Ding - One of the best experts on this subject based on the ideXlab platform.
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new insights into the india asia collision Process from cretaceous paleomagnetic and geochronologic results in the lhasa terrane
Gondwana Research, 2015Co-Authors: Tianshui Yang, Shihong Zhang, Weiwei Bian, Zhenyu Yang, Weiwei Chen, Jikai DingAbstract:Abstract To further constrain the India–Asia Collisional Process, a combined paleomagnetic and geochronologic study has been carried out on the Upper Cretaceous Jingzhushan Formation redbeds and the Lower Cretaceous Dianzhong Formation volcanic rocks dated at ~ 121–117 Ma from the Cuoqin area in the central Lhasa terrane. Stepwise thermal demagnetization successfully isolated reliable characteristic remanent magnetization (ChRM) directions that include dual polarity and pass positive fold tests at 95% and 99% confidence levels, indicating prefolding primary magnetizations. The tilt-corrected site-mean direction for 33 redbed sites is D = 316.8°, I = 30.2° with α 95 = 5.4°, corresponding to a paleopole at 49.0°N, 344.3°E with A 95 = 5.3°, and the other for 12 volcanic sites is D = 350.5°, I = 25.5° with α 95 = 7.7°, corresponding to a paleopole at 70.5°N, 292.9°E with A 95 = 7.4°. Our new paleomagnetic results, together with reliable Cretaceous paleomagnetic data obtained from the Lhasa terrane, demonstrate that the southern margin of Asia was located at ~ 15.1°N during the Cretaceous. Comparison with the apparent polar wander paths (APWP) of India and the Cretaceous–Paleocene paleopoles of the Himalayan terrane suggests that the India–Asia collision was likely a complex Process, which consists of the collision of the Lhasa and Himalayan terranes at 54.0 ± 2.1 Ma, the longtime subduction of an intra-oceanic basin between the Himalayan terrane and the Indian craton from ~ 54.0 to ~ 40.4 Ma, and the collision of the Himalayan terrane and the Indian craton at 40.4 ± 4.1 Ma. Comparing with the Late Cretaceous average pole of the East Asia APWP reveals that a latitudinal convergence of 780 ± 240 km has taken place between the Lhasa terrane and East Asia (the Hexi corridor) since the India–Asia collision; the amount of latitudinal shortening deduced from paleomagnetic data is very consistent with the 600–1000 km accommodated by the Cenozoic fold and thrust belts between the Lhasa terrane and Hexi corridor.
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paleomagnetism and u pb zircon geochronology of lower cretaceous lava flows from the western lhasa terrane new constraints on the india asia collision Process and intracontinental deformation within asia
Journal of Geophysical Research, 2014Co-Authors: Tianshui Yang, Shihong Zhang, Zhenyu Yang, Weiwei Chen, Junhong Zhang, Jikai DingAbstract:To better understand the India-Asia Collisional Process and intracontinental deformation within Asia, a paleomagnetic study has been conducted on the Qushenla Formation lava flows dated at ~132–120 Ma from the Yanhu area in the western Lhasa terrane. Stepwise thermal demagnetization isolates stable characteristic remanent magnetizations, which include dual polarity and pass fold tests at a 99% confidence level, indicating primary magnetizations. The tilt-corrected site-mean direction for 51 sites is D = 28.2°, I = 34.5°, and k = 74.3° with α95 = 2.3°, corresponding to a paleopole at 61.4°N, 192.9°E (A95 = 2.1°). Our new paleomagnetic data, combined with previous Cretaceous volcanic paleomagnetic data from the Lhasa terrane, show that the preCollisional southern margin of Asia was at ~16.8°N with a relatively E-W alignment and that the Lhasa terrane did not experience significantly discrepant north-south movement although local vertical axis rotations did take place after the Cretaceous. Comparison with the apparent polar wander paths (APWPs) of India and the Cretaceous-Paleocene paleopoles of the Tethyan Himalaya shows that the India-Asia collision was at ~54.3 Ma and the Greater India during the Paleocene had a large northern extent of ~2000 km (~18.1°) beyond its present northern margin. Comparison with the Cretaceous Eurasian APWP indicates that a latitudinal convergence of ~1000 km has taken place between the Lhasa terrane and Eurasia since the India-Asia collision. The amount of north-south shortening deduced from Cretaceous paleomagnetic data is consistent with that accommodated by the Cenozoic fold and thrust belts between the Lhasa terrane and the Hexi corridor.
Jérôme Crassous - One of the best experts on this subject based on the ideXlab platform.
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Sphere penetration by impact in a granular medium: A Collisional Process
EPL - Europhysics Letters, 2009Co-Authors: A. Seguin, Philippe Gondret, Yann Bertho, Jérôme CrassousAbstract:The penetration by a gravity-driven impact of a solid sphere into a granular medium is studied by two-dimensional simulations. The scaling laws observed experimentally for both the final penetration depth and the stopping time with the relevant physical parameters are here recovered numerically without the consideration of any microscopic solid friction but with dissipative collisions only. Dissipative Collisional Processes are thus found as essential in catching the penetration dynamics in granular matter whereas microscopic frictional Processes can only be considered as secondary effects.
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Sphere penetration by impact in a granular medium: A Collisional Process
EPL (Europhysics Letters), 2009Co-Authors: A. Seguin, Philippe Gondret, Yann Bertho, Jérôme CrassousAbstract:The penetration by a gravity driven impact of a solid sphere into a granular medium is studied by two-dimensional simulations. The scaling laws observed experimentally for both the final penetration depth and the stopping time with the relevant physical parameters are here recovered numerically without the consideration of any solid friction. Collisional Processes are thus found as essential in explaining the physics of the qualitatively observed phenomena whereas frictional Processes can only be considered as secondary effects in the granular penetration by impact.
Tianshui Yang - One of the best experts on this subject based on the ideXlab platform.
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new insights into the india asia collision Process from cretaceous paleomagnetic and geochronologic results in the lhasa terrane
Gondwana Research, 2015Co-Authors: Tianshui Yang, Shihong Zhang, Weiwei Bian, Zhenyu Yang, Weiwei Chen, Jikai DingAbstract:Abstract To further constrain the India–Asia Collisional Process, a combined paleomagnetic and geochronologic study has been carried out on the Upper Cretaceous Jingzhushan Formation redbeds and the Lower Cretaceous Dianzhong Formation volcanic rocks dated at ~ 121–117 Ma from the Cuoqin area in the central Lhasa terrane. Stepwise thermal demagnetization successfully isolated reliable characteristic remanent magnetization (ChRM) directions that include dual polarity and pass positive fold tests at 95% and 99% confidence levels, indicating prefolding primary magnetizations. The tilt-corrected site-mean direction for 33 redbed sites is D = 316.8°, I = 30.2° with α 95 = 5.4°, corresponding to a paleopole at 49.0°N, 344.3°E with A 95 = 5.3°, and the other for 12 volcanic sites is D = 350.5°, I = 25.5° with α 95 = 7.7°, corresponding to a paleopole at 70.5°N, 292.9°E with A 95 = 7.4°. Our new paleomagnetic results, together with reliable Cretaceous paleomagnetic data obtained from the Lhasa terrane, demonstrate that the southern margin of Asia was located at ~ 15.1°N during the Cretaceous. Comparison with the apparent polar wander paths (APWP) of India and the Cretaceous–Paleocene paleopoles of the Himalayan terrane suggests that the India–Asia collision was likely a complex Process, which consists of the collision of the Lhasa and Himalayan terranes at 54.0 ± 2.1 Ma, the longtime subduction of an intra-oceanic basin between the Himalayan terrane and the Indian craton from ~ 54.0 to ~ 40.4 Ma, and the collision of the Himalayan terrane and the Indian craton at 40.4 ± 4.1 Ma. Comparing with the Late Cretaceous average pole of the East Asia APWP reveals that a latitudinal convergence of 780 ± 240 km has taken place between the Lhasa terrane and East Asia (the Hexi corridor) since the India–Asia collision; the amount of latitudinal shortening deduced from paleomagnetic data is very consistent with the 600–1000 km accommodated by the Cenozoic fold and thrust belts between the Lhasa terrane and Hexi corridor.
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paleomagnetism and u pb zircon geochronology of lower cretaceous lava flows from the western lhasa terrane new constraints on the india asia collision Process and intracontinental deformation within asia
Journal of Geophysical Research, 2014Co-Authors: Tianshui Yang, Shihong Zhang, Zhenyu Yang, Weiwei Chen, Junhong Zhang, Jikai DingAbstract:To better understand the India-Asia Collisional Process and intracontinental deformation within Asia, a paleomagnetic study has been conducted on the Qushenla Formation lava flows dated at ~132–120 Ma from the Yanhu area in the western Lhasa terrane. Stepwise thermal demagnetization isolates stable characteristic remanent magnetizations, which include dual polarity and pass fold tests at a 99% confidence level, indicating primary magnetizations. The tilt-corrected site-mean direction for 51 sites is D = 28.2°, I = 34.5°, and k = 74.3° with α95 = 2.3°, corresponding to a paleopole at 61.4°N, 192.9°E (A95 = 2.1°). Our new paleomagnetic data, combined with previous Cretaceous volcanic paleomagnetic data from the Lhasa terrane, show that the preCollisional southern margin of Asia was at ~16.8°N with a relatively E-W alignment and that the Lhasa terrane did not experience significantly discrepant north-south movement although local vertical axis rotations did take place after the Cretaceous. Comparison with the apparent polar wander paths (APWPs) of India and the Cretaceous-Paleocene paleopoles of the Tethyan Himalaya shows that the India-Asia collision was at ~54.3 Ma and the Greater India during the Paleocene had a large northern extent of ~2000 km (~18.1°) beyond its present northern margin. Comparison with the Cretaceous Eurasian APWP indicates that a latitudinal convergence of ~1000 km has taken place between the Lhasa terrane and Eurasia since the India-Asia collision. The amount of north-south shortening deduced from Cretaceous paleomagnetic data is consistent with that accommodated by the Cenozoic fold and thrust belts between the Lhasa terrane and the Hexi corridor.
A. Seguin - One of the best experts on this subject based on the ideXlab platform.
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Sphere penetration by impact in a granular medium: A Collisional Process
EPL - Europhysics Letters, 2009Co-Authors: A. Seguin, Philippe Gondret, Yann Bertho, Jérôme CrassousAbstract:The penetration by a gravity-driven impact of a solid sphere into a granular medium is studied by two-dimensional simulations. The scaling laws observed experimentally for both the final penetration depth and the stopping time with the relevant physical parameters are here recovered numerically without the consideration of any microscopic solid friction but with dissipative collisions only. Dissipative Collisional Processes are thus found as essential in catching the penetration dynamics in granular matter whereas microscopic frictional Processes can only be considered as secondary effects.
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Sphere penetration by impact in a granular medium: A Collisional Process
EPL (Europhysics Letters), 2009Co-Authors: A. Seguin, Philippe Gondret, Yann Bertho, Jérôme CrassousAbstract:The penetration by a gravity driven impact of a solid sphere into a granular medium is studied by two-dimensional simulations. The scaling laws observed experimentally for both the final penetration depth and the stopping time with the relevant physical parameters are here recovered numerically without the consideration of any solid friction. Collisional Processes are thus found as essential in explaining the physics of the qualitatively observed phenomena whereas frictional Processes can only be considered as secondary effects in the granular penetration by impact.