Effective interactions between O-sized anions in various electrolyte solutions were calculated by using the integral equation theory with some simple models. The results indicated that only multivalent cations mediated a strong effective attraction between O-sized anions at a certain concentration. The effective interaction turned from repulsive to attractive as the electrolyte concentration increased, and the effective attraction decreased when more electrolyte was added. Moreover, the effective interactions between O-sized anions in the electrolyte solution did not present a long repulsive tail, although the effective attraction caused by the divalent cations appeared. By contrast, the effective attraction mediated by monovalent cations and the reentrant behavior did not appear and the effective interaction was basically repulsive. These behaviors agree with the experimental results for reentrant condensation of acidic proteins in various electrolyte solutions. The calculated results suggest that the dissociated carboxylic acidic groups on the proteins form attractive patches between proteins under certain concentration conditions.
Acknowledgements: We are grateful to M Mario Coriasco for technical assistance.Competing interests: None. Patient consent: Obtained. REFERENCES 1. Dalmau J, Graus F, Rosenblum MK, et al. Anti-Hu-associated paraneoplastic encephalomyelitis/sensory neuronopathy. A clinical study of 71 patients. Medicine (Baltimore) 1992;71:59-72. 2. Pittock SJ, Lucchinetti CF, Lennon VA. Anti-neuronal nuclear autoantibody type 2: paraneoplastic accompaniments. Ann Neurol 2003;53:580-7. 3. Dietl HW, Pulst SM, Engelhardt P, et al. Paraneoplastic brainstem encephalitis with acute dystonia and central hypoventilation J Neurol 1982;227:229-38. 4. Gómez-Choco MJ, Zarranz JJ, Saiz A, et al. Central hypoventilation as the presenting symptom in Hu associated paraneoplastic encephalomyelitis. J Neurol Neurosurg Psychiatry 2007;78:1143-5. 5. Voltz R. Paraneoplastic neurological syndromes: an update on diagnosis, pathogenesis and therapy. Lancet Neurol 2002;5:294-305. Visualised manganese ion within the basal ganglia and long axonal tractsA 53-year-old male was admitted to our ward because of recurrent generalised tonic-clonic seizures. He had consumed 700-1300 ml of Japanese sake (16% alcohol) daily since the age of 19 years, and had suffered from liver cirrhosis and varices in both the oesophagus and stomach since the age of 40 years. The seizures were successfully treated with oral diazepam (15 mg daily) and nitrazepam (5 mg daily). After recovering from the seizures, he exhibited no neurological abnormalities other than a slight intention tremor. His EEG was normal. A T1-weighted MRI study showed strongly high signal areas in the globus pallidus and red nuclei as well as high signal areas throughout the subcortical white matter and internal capsules, whereas T2-weighted pictures did not (fig 1). These signals are known to represent manganese ion, 1 which had accumulated in neurons and was transported downward within the axons 2 ; the values of serum manganese and iron were 3.9 mg/dl and 30 mg/ dl, respectively. Thereafter, the patient began to attend psychoeducational meetings and behavioural therapy for alcoholism. He was discharged home after 45 days. REFERENCE 1. Spampinato MV, Castillo M, Rojas R, et al. Magnetic resonance imaging findings in substance abuse: alcohol and alcoholism and syndromes associated with alcohol abuse. Top Magn Reson Imaging 2005;16:223-30. 2. Pautler RG. In vivo, trans-synaptic tract-tracing utilizing manganese-enhanced magnetic resonance imaging (MEMRI). NMR Biomed 2004;17:595-601.Figure 1 Magnetic resonance images recorded on the second hospital day of the case. The upper two pictures clearly show the distribution and the density of manganese ion.
Kinesin-1 is a motor protein that moves along microtubules in a hand-overhand manner. Recent crystal structure solved in our lab showed that kinesin head undergoes ~25 degree rotational motion of a subdomain upon ATP binding. In this study, we directly observed ATP-dependent rotational motion of the subdomain during processive motility using gold nanorod attached to one of the head. The centroid position and the angle of the nanorod were determined by fitting the focused dark-field image recorded at 100 μs temporal resolution to simulated PSF, and demonstrated that the angle of the nanorod showed two state transition while the labeled head binds to microtubule. We will also show the results of kinetics analysis and discuss the implication for the gating mechanism. 2P146X 線 1 分子計測による分子モーターの構造揺らぎ測定 X-ray Single Molecule Observations of Structural Fluctuations in Molecular MotorsKeigo Ikezaki 1 , Naruki Hara 1 , Hiroshi Sekiguchi 2 , Naoto Yagi 2 , Yuji Sasaki 1Molecular motors alter their molecular structures and exert mechanical force using the chemical energy of ATP hydrolysis. So for, many researchers revealed structural changes of molecular motors during ATP hydrolysis by using optical microscopy and atomic force microscopy. However, no one succeeds to clarify inter molecular fluctuations during ATP hydrolysis because of the resolution limit of their methods. Recently, we are trying to observe inter molecular fluctuations of myosin molecular motors using DXT measurement (described below). At the meeting, we will report the latest progress. Please look forward to it! Note: Diffracted X-ray Tracking DXT allows us to know the orientations of gold nano-crystals attached to protein surfaces.(SPring-8,BL40XU) Myosin IXb is a single-headed processive motor. Recent studies from two groups reported that the motility direction of myosin IXb was to either barbed end or point end direction. This discrepancy may arise from different sources of myosin or methods of actin preparation. Therefore, we hypothesized that the motility of myosin IXb is highly sensitive to subtle differences in actin structure. In this study, we first established a reproducible baculovirus-dependent system to express motile human myosin IXb. Movement of this myosin on Cy3-actin was to the barbed end, but interestingly, phalloidin was slightly inhibitory (0.66-fold slower). We will report the motile properties of several other types of actin filaments on this myosin. current across membrane down the electrochemical potential gradient is thought to drive the rotary motion of c-ring relative to a-subunit. As a molecular mechanism of the rotary motion, the half-channel model is widely accepted, where the two different H + channels at the interface of a-subunit and c-ring are assumed to play a key role. To investigate this model, we conducted all-atom molecular dynamics simulation, and analyzed water distribution in the membraneembedded region. We further studied the inter-subunit motion between cring and a-subunit. 2P149 タンパク質間の実行相互作用:多価カチオンを介した引力 パッチ間相...
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