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11.
Michaela Ludolphs Daniela Schneeberger Tolga Soykan Jonas Sch?fer Theofilos Papadopoulos Nils Brose Hermann Schindelin Claudia Steinem 《The Journal of biological chemistry》2016,291(1):244-254
The regulatory protein collybistin (CB) recruits the receptor-scaffolding protein gephyrin to mammalian inhibitory glycinergic and GABAergic postsynaptic membranes in nerve cells. CB is tethered to the membrane via phosphoinositides. We developed an in vitro assay based on solid-supported 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine membranes doped with different phosphoinositides on silicon/silicon dioxide substrates to quantify the binding of various CB2 constructs using reflectometric interference spectroscopy. Based on adsorption isotherms, we obtained dissociation constants and binding capacities of the membranes. Our results show that full-length CB2 harboring the N-terminal Src homology 3 (SH3) domain (CB2SH3+) adopts a closed and autoinhibited conformation that largely prevents membrane binding. This autoinhibition is relieved upon introduction of the W24A/E262A mutation, which conformationally “opens” CB2SH3+ and allows the pleckstrin homology domain to properly bind lipids depending on the phosphoinositide species with a preference for phosphatidylinositol 3-monophosphate and phosphatidylinositol 4-monophosphate. This type of membrane tethering under the control of the release of the SH3 domain of CB is essential for regulating gephyrin clustering. 相似文献
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15.
B. Müller E. Schlichting L. Bischoff K. Schügerl 《Applied microbiology and biotechnology》1987,26(1):36-41
Summary Penicillin G was extracted from a model medium with a secondary amine (Amberlite LA-2) as carrier in n-butylacetate as solvent in a 7.6 m high pilot plant Karr-column at different stroke frequencies, throughput of the phases, concentrations of Penicillin G and carrier and ratios of the throughputs of the aqueous and organic phases. Up to penicillin concentrations of 30 gl–1, throughputs of the aqueous phase of 100 lh–1 and throughput ratios of the aqueous phase-to-organic phase of 3, very high degrees of extraction (99%) can be achieved with a penicillin loss below 1%.Symbols a
specific interfacial area with regard to the volume of the continuous phase
- C
partition coefficient
- cA, cA, i
concentration of carrier (sec. amine) in the bulk at the interface
- cAHP, cAHP, i
concentration of complex in the bulk at the interface
- cH
proton concentration
- cHPa, cHPa,i
concentration of free acid in the bulk of the aqueous phase at the interface
- cHPo, cHPo, i
concentration of free acid in the bulk of the organic phase, at the interface
- cP, cP, i
concentration of acid anions in the bulk of the aqueous phase, at the interface
- d32
Sauter droplet diameter
- E
degree of extraction
- f
stroke frequency
- KG
reaction equilibrium constant
- Kphys
distribution coefficient
- N
number of stages in cascade
- t
mean residence time of the aqueous phase
-
aq
throughput of the aqueous phase
-
o
throughput of the organic phase
- Z
dimensionless longitudinal coordinate of the column with regard to its active length (4 m)
-
holdup of the organic phase 相似文献
16.
Summary To eliminate the product inhibition and increase the productivity of butanol formation, a continuously operated membrane bioreactor was connected to a four-stage mixer-settler cascade. Clostridium acetobutylicum was cultivated in this reactor. Butanol was selectively extracted with butyric acid saturated n-decanol from the cell-free cultivation medium, and the butanol-free medium was refed into the reactor. Due to the high boiling point of decanol, the recovery of butanol from the decanol solution is easy. The partition coefficient and selectivity of butanol in the cultivation medium-decanol-system is sufficiently high for removing it from the medium. Direct contact of the cells with the decanol phase causes cell damage. However, decanol is practically insoluble in the fermentation medium, thus the contact of the cell-free medium with the solvent phase does not influence of cell growth and product formation. At a dilution rate of D
z=0.1 h-1, the butanol productivity was increased by removing butanol from the medium by a factor of four. A further increase was prevented by a contaminant of the technical decanol, which was identified by GC-MS-analysis as 1-,3-hexandiol.Symbols
D
dilution rate, h-1
-
D
eff
effective dilution rate (Eq. 3), h-1
-
D
Ex
extraction dilution rate (Eq. 3), h-1
-
D
g
dilution rate of cell suspension in reactor-filter-system, h-1
-
E
degree of extraction (Eq. 3), l
-
P
product concentration in medium after extraction, g l-1
-
P
O
product concentration in reactor, g l-1
-
R
P
productivity and product formation rate, g l-1 h-1
-
q
p
S
specific product formation coefficient with regard to the cell growth rate, l
-
V
F
volume of cell suspension in filter module, l
-
V
g
volume of the cell suspension in reactor and in filter module V
g
=V
R
+V
F
, l
-
V
R
volume of cell suspension in ractor, l
-
v
O
cell free feed rate, l h-1
-
v
1
flow rate of cell suspension leaves the reactor, l h-1
-
v
E
flow rate of decanol through the extractor, l h-1
-
v
w
flow rate of the cell free medium through the filter modul, l h-1
-
X
cell mass concentration, g l-1
-
specific growth rate of the cells, h-1
Dedicated to Professor Dr. H. J. Rehm on the occasion of his 60th birthday 相似文献
17.
B. Müller E. Schlichting L. Bischoff K. Schügerl 《Applied microbiology and biotechnology》1987,26(3):206-210
Summary Penicillin G was extracted from mycelfree fermentation broths by means of the carrier (Amberlite LA-2) in n-butylacetate at pH 5 in a 7.6 m high pilot plant Karr-column with degrees of extraction E=98–99% and penicillin enrichments up to 3. The reextraction was carried out with phosphate buffer at pH-values above 7.5 with degree of extractions E=86–88% and penicillin enrichments up to 3. The penicillin and carrier losses were negligible. The influence of the process variables on the extraction degree was investigated. The penicillin extraction of the model medium and the fermentation broths were compared. Recommendations are given for the optimal penicillin recovery with reactive extraction.Symbols a
specific interfacial area with regard to the volume of the continuous phase
- cA
concentration of carrier
- cAHP,O
concentration of complex in feed
- cP,cP,O
concentration of penicillin acid anion in theaqueous phase, in the feed
-
d
32
Sauter droplet diameter
-
E
degree of extraction
-
f
stroke frequency
-
V
aq
throughput of the aqueous phase
-
V
0
throughput of the organic phase
-
Z
dimensionsless longitudinal coordinate of the column with regard to its active length (4m)
-
holdup of the organic phase 相似文献
18.
The intracellular localisation of phytochrome and ubiquitin in irradiated oat coleoptiles was analysed by electron microscopy. We applied indirect immunolabeling with polyclonal antibodies against phytochrome from etiolated oat seedlings or polyclonal antibodies against ubiquitin from rabbit reticulocytes, together with a goldcoupled second antibody, on serial ultrathin sections of resin-embedded material. Immediately after a 5-min pulse of red light-converting phytochrome from the red-absorbing (Pr) to the far-redabsorbing (Pfr) form-the label for phytochrome was found to be sequestered in electron-dense areas. For up to 2 h after irradiation, the size of these areas increased with increasing dark periods. The ubiquitin label was found in the same electrondense areas only after a dark period of 30 min. A 5 min pulse of far-red light, which reverts Pfr to Pr, given immediately after the red light did not cause the electron-dense structures to disappear; moreover, they contained the phytochrome label immediately after the far-red pulse. In contrast, after the reverting far-red light pulse, ubiquitin could only be visualised in the electron-dense areas after prolonged dark periods (i.e. 60 min). The relevance of these data to light-induced phytochrome pelletability and to the destruction of both Pr and Pfr is discussed.Abbreviations FR
far-red light; Pfr
- Pr
far-red-absorbing and red-absorbing forms of phytochrome, respectively
- R
red light 相似文献
19.
Crystallization and preliminary x-ray diffraction studies of recombinant human interleukin-1 beta 总被引:3,自引:0,他引:3
Recombinant human interleukin-1 beta has been crystallized into a tetragonal cell. The unit cell constants are a = b = 54.9 A, c = 76.8 A, and alpha = beta = gamma = 90 degrees. The crystals diffract to better than 1.9 A and are suitable for high resolution data collection. The crystallization conditions and general crystal data are presented. 相似文献
20.
InCallithrix, Saguinus, Aotus, andCallicebus other group members than the mother participate in infant care. Differences among these species are obvious in respect to the time of being off any caregiver, and in respect to the carrying position (Aotus andCallicebus). Alloparental care, a basic behaviour pattern in these species, has evolved from the parking behaviour of the prosimians. The infants are «parked» at other group members. 相似文献