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1.
Summary The rare phenotypes PGM1, determined by alleles PGM
3
1
, PGM
4
1
, PGM
6
1
, and PGM
7
1
were examined by starch gel electrophoresis and cellulose acetate gel isoelectric focusing and were compared with the commonest phenotypes of PGM1.The frequencies of the rare genes found in the Polish populations were as follows: in Lublin, PGM
3
1
=0.0002, PGM
4
1
=0.0005, PGM
6
1
=0.0010, and PGM
7
1
=0.0005; in Wroclaw, PGM
3
1
=0.0000, PGM
4
1
=0.0005, PGM
6
1
=0.0007, and PGM
7
1
=0.0002.The results suggest that the F and S type variants of the genes PGM
4
1
and PGM
7
1
probably do not occur. It is still possibile that F and S variants exist for the genes PGM
3
1
and PGM
6
1
. 相似文献
2.
Annie Sainsard-Chanet 《Molecular & general genetics : MGG》1976,145(1):23-30
Summary The slow growing mutant cl1 of Paramecium, previously described (Sainsard, Claisse and Balmefrezol, 1974) differs from wild-type by a single recessive nuclear mutation and by a particular mitochondrial phenotype (Mcl) that gene cl
1 distinguishes from the wild-type mitochondrial phenotype (M+). A further analysis of these nucleo-mitochondrial interactions was carried out by confronting the genes cl
1 and cl
1
+
with mixed populations of M+ and Mcl mitochondria obtained after cytoplasmic exchange at conjugation. The following results were obtained: 1. M+ and Mcl mitochondria introduced respectively into mutant and wild-type cells do not multiply easily; 2. when a mixed population (M++Mcl) is established, both mitochondrial types are maintained during the growth of the F1 heterozygous cl
1/cl
1
+
clones; 3. when the nuclear segregation occurs in F2, the formation of homozygotes cl
1/cl
1 or cl
1
+
/cl
1
+
is soon followed by the segregation of the two mitochondrial types, Mcl or M+, reconstituting the two parental nucleo-mitochondrial associations.This paper is dedicated to Professor T.M. Sonneborn on the occasion of his 70th birthday 相似文献
3.
Dr. Y. Efron 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1973,43(7):323-328
Summary The genetic control of acid phosphatase-1 (AP
1) activity in pollen of maize was studied by crossing inbred lines having different AP
1 isozymes and different activity levels of the A P
1 enzyme. Usually, the intensities of the SS and FF isozyme bands were not equal in pollen of A P
1
S
/A P
1
F
heterozygous F
1 hybrids, but the relative intensities of the two bands were not correlated to the activity levels of the parental lines. The A P
1
S
/A P
1
S
and A P
1
F
/A P
1
F
F
2 populations differed in their mean level of activity. Both populations showed segregation in the activity levels indicating single gene control. The intensity ratios of the SS and FF bands in the different heterozygous A P
1
S
/A P
1
F
F
2 plants did not segregate. The results support the competition model for gene regulation proposed by Schwartz (1971). 相似文献
4.
Oscillator strengths of the 1La and 1Lb absorption bands of tryptophan and several other indoles 总被引:1,自引:0,他引:1
The intensities of the indolyl 1La and 1Lb absorption bands were investigated by using 5-methoxyindole as a model compound. With 5-methoxyindole dissolved in weakly interacting solvents, almost the entire 1Lb electronic transition occurs at longer wavelengths than the 1La transition. The resolved spectrum of 5-methoxyindole permitted estimation of its oscillator strengths and also those of other indoles dissolved in cyclohexane: indole, 0.129 (1La), 0.019 (1Lb); 5-methylindole, 0.129 (1La), 0.027 (1Lb); 5-methoxyindole, 0.138 (1La), 0.045 (1Lb); 3-methylindole and N-stearyl-L -tryptophan n-hexyl ester, 0.127 (1La), 0.027 (1Lb). Hydrogen bonding to 1-methyl-2-pyrrolidinone does not measurably affect the total near-ultraviolet oscillator strength of indoles (less than 5% change). In water and ethanol, the oscillator strength of 3-methylindole and tryptophan is 15–20% less than that of 3-methylindole dissolved in cyclohexane. The spectra of the N-stearyl n-hexyl esters of tryptophan and 1-methyltryptophan dissolved in methylcyclohexane can be generated by using 1La and 1Lb bands having shapes similar to those observed for 5-methoxyindole, if the 1La and 1Lb bands are shifted so that their O-O bands overlap (289.5 nm for tryptophan and 299.5 nm for 1-methyltryptophan). 相似文献
5.
Mohammad A. Kamal Abdulaziz A. Al-Jafari 《Journal of enzyme inhibition and medicinal chemistry》2013,28(2):201-213
Limited reports as compared to other insecticides appear in the literature for acetylcholinester-ase (AChE) inhibition by diazinon. In the current study, new kinetic parameters of AChE inhibition by diazinon have been investigated. The assay was done with bovine retinal AChE using two different substrate (ASCh) concentrations in the absence and presence of diazinon (0.08-1.28 mM). The optical density was monitored up to 25min (reaction time) for the assay. New kinetic parameters (k1oms, k1sms, k1oms, k1sms, k1asms and k1asms) were calculated from these experimental data. 相似文献
6.
In this study, the response of N2 fixation to elevated CO2 was measured in Scirpus olneyi, a C3 sedge, and Spartina patens, a C4 grass, using acetylene reduction assay and 15N2 gas feeding. Field plants grown in PVC tubes (25 cm long, 10 cm internal diameter) were used. Exposure to elevated CO2 significantly (P < 0·05) caused a 35% increase in nitrogenase activity and 73% increase in 15N incorporated by Scirpus olneyi. In Spartina patens, elevated CO2 (660 ± 1 μ mol mol − 1) increased nitrogenase activity and 15N incorporation by 13 and 23%, respectively. Estimates showed that the rate of N2 fixation in Scirpus olneyi under elevated CO2 was 611 ± 75 ng 15N fixed plant − 1 h − 1 compared with 367 ± 46 ng 15N fixed plant − 1 h − 1 in ambient CO2 plants. In Spartina patens, however, the rate of N2 fixation was 12·5 ± 1·1 versus 9·8 ± 1·3 ng 15N fixed plant − 1 h − 1 for elevated and ambient CO2, respectively. Heterotrophic non-symbiotic N2 fixation in plant-free marsh sediment also increased significantly (P < 0·05) with elevated CO2. The proportional increase in 15N2 fixation correlated with the relative stimulation of photosynthesis, in that N2 fixation was high in the C3 plant in which photosynthesis was also high, and lower in the C4 plant in which photosynthesis was relatively less stimulated by growth in elevated CO2. These results are consistent with the hypothesis that carbon fixation in C3 species, stimulated by rising CO2, is likely to provide additional carbon to endophytic and below-ground microbial processes. 相似文献
7.
Summary A total of 345 haemolysates previously phenotyped by starch gel electrophoresis and known to contain the products of the PGM
1
3
, PGM
1
6
, and PGM
1
7
alleles have been analyzed by thin layer polyacrylamide gel isoelectric focussing in the pH range 5–7. Two common subtypes, 3+and 3-, of the PGM
1
3
allele have been found in a number of Pacific populations. A single form of the PGM
1
7
allele was observed in the Western Caroline Islands. In contrast, one of two Indian PGM17 variants focussed to a different position when compared with the form found at polymorphic frequency in the Western Caroline Islands. Only one type of the PGM
1
6
allele was detected during the present investigation. 相似文献
8.
N. D. Jambhale Y. S. Nerkar 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,71(1):122-125
Summary Genetic studies on radiation-induced chlorina and variegated mutants of okra (Abelmoschus esculentus (L.) Moench) revealed the existence of an unstable gene. The normal green color of the leaves is controlled by duplicate genes C1 and C2, either of which produces the green colour. The chlorina plants are C
1
C
1
C
2
C
2. The allele c
1
v
is dominant to both C
1 and C
2 but is unstable. The homozygote c
1
v
c
1
v
c
2
c
2 is a normal green while the heterozygote c
i
v
c
1
c
2
c
2 has a variegated phenotype as a result of the mutation of c
1
v
to c
1 during development. In green plants with a c
1
v
c{sh1/v}c
2
c
2 genotype, the autonomous mutation of one of the c
1
v
alleles to c
1 may take place at the pre-meiotic stage. In the variegated genotype (c
1
v
c
1
c
2
c
2), the mutation of c
1 to c
1
v
may take place in early ontogeny, thus producing green plants. The allele C
1, when associated with c
1
v
in a heterozygous condition, mutates to c
1 at the pre-meiotic stage even in the presence of the allele C
2. 相似文献
9.
Bork A. Berghoff Jens Glaeser Cynthia M. Sharma Jörg Vogel Gabriele Klug 《Molecular microbiology》2009,74(6):1497-1512
Exposure to oxygen and light generates photooxidative stress by the bacteriochlorophyll a mediated formation of singlet oxygen (1O2) in Rhodobacter sphaeroides. Our study reports the genome‐wide search for small RNAs (sRNAs) involved in the regulatory response to 1O2. By using 454 pyrosequencing and Northern blot analysis, we identified 20 sRNAs from R. sphaeroides aerobic cultures or following treatment with 1O2 or superoxide (O–2). One sRNA was specifically induced by 1O2 and its expression depends on the extracytoplasmic function sigma factor RpoE. Two sRNAs induced by 1O2 and O–2 were cotranscribed with upstream genes preceded by promoters with target sequences for the alternative sigma factors RpoHI and RpoHII. The most abundant sRNA was processed in the presence of 1O2 but not by O–2. From this and a second sRNA a conserved 3′‐segment accumulated from a larger precursor. Absence of the RNA chaperone Hfq changed the half‐lives, abundance and processing of 1O2‐affected sRNAs. Orthologues of three sRNA genes are present in different alpha‐proteobacteria, but the majority was unique to R. sphaeroides or Rhodobacterales species. Our discovery that abundant sRNAs are affected by 1O2 exposure extends the knowledge on the role of sRNAs and Hfq in the regulatory response to oxidative stress. 相似文献
10.
Summary Phenotypes of the erythrocyte enzymes phosphoglucomutase (PGM) (n-587), adenylate kinase (AK) (n=695), and adenosine deaminase (ADA) (n=616) were determined by horizontal starch gel electrophoresis in Thai subjects from norther Thailand, mainly from the provinces of Chiang Mai and Lamphun. The following gene frequencies were calculated: PGM
1
1
0.7385 PGM
1
2
0.2487 PGM
1
6
0.0102 PGM
1
7
0.0026, AK
1 0.9950 AK
2 0.0050, ADA
1 0.9180 ADA
2 0.0820.The regular, apparently autosomal transmission of the PGM
1
6
and PGM
1
7
alleles was demonstrated in 7 families revealing sufficient data.
Established and supported by Stiftung Volkswagenwerk. 相似文献
Zusammenfassung Die Phänotypen der Erythrocytenenzyme Phosphoglucomutase (PGM) (n=587), Adenylatkinase (AK) (n=695), and Adenosindeaminase (ADA) (n=616) wurden mittles horizontaler Stärkegelelektrophorese bei Thailändern aus Nordthailand, hauptsächlich aus den Provinzen Chiang Mai und Lamphun, bestimmt. Auf Grund der Ergebnisse wurden die in der englischen Zusammenfassung angegebenen Genfrequenzen berechnet. Die regelmäßige, anschinend autosomale Vererbung der Allele PGM 1 6 und PGM 1 7 wurde in 7 Familien mit ausreichenden Daten nachgewiesen.
Established and supported by Stiftung Volkswagenwerk. 相似文献
11.
Both conventional and genetic engineering techniques can significantly improve the performance of animal cell cultures for the large-scale production of pharmaceutical products. In this paper, the effect of such techniques on cell yield and antibody production of two NS0 cell lines is presented. On the one hand, the effect of fed-batch cultivation using dialysis is compared to cultivation without dialysis. Maximum cell density could be increased by a factor of ~5–7 by dialysis fed-batch cultivation. On the other hand, suppression of apoptosis in the NS0 cell line 6A1 bcl-2 resulted in a prolonged growth phase and a higher viability and maximum cell density in fed-batch cultivation in contrast to the control cell line 6A1 (100)3. These factors resulted in more product formation (by a factor ~2). Finally, the adaptive model-based OLFO controller, developed as a general tool for cell culture fed-batch processes, was able to control the fed-batch and dialysis fed-batch cultivations of both cell lines.Abbreviations A membrane area (dm2) - c Glc,F glucose concentration in nutrient feed (mmol L–1) - c Glc,FD glucose concentration in dialysis feed (mmol L–1) - c Glc,i glucose concentration in inner reactor chamber (mmol L–1) - c Glc,o glucose concentration in outer reactor chamber (dialysis chamber) (mmol L–1) - c Lac,FD lactate concentration in dialysis feed (mmol L–1) - c Lac,i lactate concentration in inner reactor chamber (mmol L–1) - c Lac,o lactate concentration in outer reactor chamber (dialysis chamber) (mmol L–1) - c LS,FD limiting substrate concentration in dialysis feed (mmol L–1) - c LS,i limiting substrate concentration in inner reactor chamber (mmol L–1) - c LS,o limiting substrate concentration in outer reactor chamber (dialysis chamber) (mmol L–1) - c Mab monoclonal antibody concentration (mg L–1) - F D feed rate of dialysis feed (L h–1) - F Glc feed rate of nutrient concentrate feed (L h–1) - K d maximum death constant (h–1) - k d,LS death rate constant for limiting substrate (mmol L–1) - k Glc monod kinetic constant for glucose uptake (mmol L–1) - k Lac monod kinetic constant for lactate uptake (mmol L–1) - k LS monod kinetic constant for limiting substrate uptake (mmol L–1) - K Lys cell lysis constant (h–1) - K S,Glc monod kinetic constant for glucose (mmol L–1) - K S,LS monod kinetic constant for limiting substrate (mmol L–1) - µ cell-specific growth rate (h–1) - µ d cell-specific death rate (h–1) - µ d,min minimum cell-specific death rate (h–1) - µ max maximum cell-specific growth rate (h–1) - P Glc membrane permeation coefficient for glucose (dm h–1) - P Lac membrane permeation coefficient for lactate (dm h–1) - P LS membrane permeation coefficient for limiting substrate (dm h–1) - q Glc cell-specific glucose uptake rate (mmol cell–1 h–1) - q Glc,max maximum cell-specific glucose uptake rate (mmol cell–1 h–1) - q Lac cell-specific lactate uptake/production rate (mmol cell–1 h–1) - q Lac,max maximum cell-specific lactate uptake rate (mmol cell–1 h–1) - q LS cell-specific limiting substrate uptake rate (mmol cell–1 h–1) - q LS,max maximum cell-specific limiting substrate uptake rate (mmol cell –1 h–1) - q Mab cell-specific antibody production rate (mg cell–1 h–1) - q MAb,max maximum cell-specific antibody production rate (mg cell–1 h–1) - t time (h) - V i volume of inner reactor chamber (culture chamber) (L) - V o volume of outer reactor chamber (dialysis chamber) (L) - X t total cell concentration (cells L–1) - X viable cell concentration (cells L–1) - Y Lac/Glc kinetic production constant (stoichiometric ratio of lactate production and glucose uptake) (–) 相似文献
12.
Masui DC Furriel RP Mantelatto FL McNamara JC Leone FA 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2003,134(4):631-640
The kinetic properties of a microsomal gill (Na+,K+)-ATPase from the blue crab Callinectes danae were analyzed using the substrate p-nitrophenylphosphate. The (Na+,K+)-ATPase hydrolyzed PNPP obeying cooperative kinetics (n=1.5) at a rate of V=125.4±7.5 U mg−1 with K0.5=1.2±0.1 mmol l−1; stimulation by potassium (V=121.0±6.1 U mg−1; K0.5=2.1±0.1 mmol l−1) and magnesium ions (V=125.3±6.3 U mg−1; K0.5=1.0±0.1 mmol l−1) was cooperative. Ammonium ions also stimulated the enzyme through site–site interactions (nH=2.7) to a rate of V=126.1±4.8 U mg−1 with K0.5=13.7±0.5 mmol l−1. However, K+-phosphatase activity was not stimulated further by K+ plus NH4+ ions. Sodium ions (KI=36.7±1.7 mmol l−1), ouabain (KI=830.3±42.5 μmol l−1) and orthovanadate (KI=34.0±1.4 nmol l−1) completely inhibited K+-phosphatase activity. The competitive inhibition by ATP (KI=57.2±2.6 μmol l−1) of PNPPase activity suggests that both substrates are hydrolyzed at the same site on the enzyme. These data reveal that the K+-phosphatase activity corresponds strictly to a (Na+,K+)-ATPase in C. danae gill tissue. This is the first known kinetic characterization of K+-phosphatase activity in the portunid crab C. danae and should provide a useful tool for comparative studies. 相似文献
13.
Norio Shiomi Jiro Yamada Masao Izawa 《Bioscience, biotechnology, and biochemistry》2013,77(11):2233-2244
Nine fructo-oligosaccharides, synthesized in vitro from sucrose by an enzyme preparation from asparagus roots, were isolated and their structures were elucidated to be 1F (1-β-fructofuranosyl)n sucrose [n = 1 (1-kestose), 2 (nystose) and 3], 6G (1-β-fructofuranosyl)n sucrose [n=1 (neokestose), 2 and 3] and 1F (1-β-fructofuranosyl)m-6G (1-β-fructofuranosyl)n sucrose [m=1, n=1; m=2, n =1; and m =1, n=2]. These saccharides are all known to occur naturally in asparagus roots, but 6G (1-β-fructofuranosyl)3 sucrose and 1F (1-β-fructofuranosyl)m-6G-(1-β-fructofuranosyl)n sucrose (m=1, n =1; and m=1, n=2) were the first saccharides enzymatically synthesized in vitro. Also three types of fructosyltransferases were presumed to be involved in the biosynthesis of these oligosaccharides in asparagus roots. 相似文献
14.
F. Oury-Donat I. A. Lefevre O. Thurneyssen T. Gauthier A. Bordey† P. Feltz† X. Emonds-Alt G. Le Fur P. Soubrie 《Journal of neurochemistry》1994,62(4):1399-1407
The effects of a novel nonpeptide NK1 tachy-kinin receptor antagonist, SR 140333, on the functional consequences of NK1 receptor activation in a human astrocytoma cell line, U373MG, were investigated. Radioligand binding conducted with 125l-Bolton-Hunter substance P revealed a competitive inhibition by SR 140333 and its R enantiomer SR 140603 with Ki values of 0.74 and 7.40 nM, respectively. The NK1-selective agonist, [Sar9,Met(O2)11]-substance P, stimulated the formation of inositol phosphates with an EC50 of 3.8 × 10?9M. SR 140333 blocked the stimulatory effect of this agonist (10?7M) with an IC50 of 1.6 × 10?9M,whereas the effect of another NK1 agonist, septide (EC50= 1.5 × 10?8M)was antagonized with an IC50 of 2.1 × 10?10M.Enhancement of [3H]taurine release by [Sar9,Met(O2)11]-substance P (EC50= 7.4 × 10?9M) was also inhibited by SR 140333 with an IC50 of 1.8 × 10?9 M. SR 140603 was 10-fold less potent than SR 140333 in inhibiting inositol monophosphate formation and [3H]taurine release. The calcium mobilization induced by [Sar9,Met(O2)11]-substance P (10?8M) was totally prevented by 10?8MSR 140333. Patchclamp experiments showed that SR 140333 depressed the outward current evoked by 5 × 10?8M [Sar9, Met(O2)11]-substance P with an IC50 of 1.3 × 10?9M. The expression of c-fos was stimulated by [Sar9,Met(O2)11]-substance P with an EC50 of 2.5 × 10?10M, an effect that was also inhibited by SR 140333 with an IC50 of 1.1 × 10?9M. The present results illustrate the sequential events of the response elicited by NK1 agonists, which were antagonized by SR 140333, demonstrating its powerful NK1 antagonist activity on a functional basis. 相似文献
15.
We determined if any naturally occurring peptides could act as substrates or inhibitors of the bifunctional, Zn2+ metalloenzyme LTA4 hydrolase/aminopeptidase (E.C. 3.3.2.6). Several opioid peptides including met5-enkephalin, leu5-enkephalin, dynorphin1–6, dynorphin1–7, and dynorphin1–8 competitively inhibited the hydrolysis of L-proline-p-nitroanilide by leukotriene A4 hydrolase/ aminopeptidase, consistent with an interaction at its active site. The enzyme catalyzed the N-terminal hydrolysis of tyrosine from met5-enkephalin with Km =450 ± 58 μM and Vmax =4.9 ± 0.6 nmol-hr−1-ug−1 and from leu5-enkephalin with Km =387 ± 90 μM and Vmax =6.2 ± 2.5 nmol-hr−1-ug−1. Bestatin, captopril and carnosine inhibited the hydrolysis of the enkephalins. It is noteworthy that the bifunctional catalytic traits of this enzyme include generation of an hyperalgesic substance, LTB4, and inactivation of analgesic opioid peptides. 相似文献
16.
Ian C. Murfet 《Physiologia plantarum》1990,79(3):497-505
Dwarf pea (Pisum sativum L.) plants with genotypes cryc and crys responded differently when an 8 h photoperiod (8 h daylight, 16 h dark) was extended to 24 h (8 h daylight, 16 h incandescent light). Genotype cryc showed up to a 4-fold increase in internode length, sustained by increases in both cell length (particularly of epidermal cells) and cell number (particularly of cortical cells) while crys plants showed up to a 2-fold increase in internode length sustained mostly by an increase in cell number. Under an 8 h (daylight) photoperiod the two genotypes did not differ in their sensitivity to applied gibberellin A1 (GA1) and they showed a similar pattern of response. GA1 significantly increased internode length, cell length and cell number in both genotypes. Incandescent light did not increase the size of the response to GA1 except for crys plants at high dose rates of GA1 (29–58 nmol). At saturating doses of GA1 the two genotypes attained a similar peak internode length; incandescent light increased the peak by about 40%. GA1 increased the rate of leaf appearance by up to 33% while incandescent light reduced the rate by 4–7%. The elongation response of the more mature internodes of cryc plants to GA1 or incandescent light was due primarily to an increase in cell length whereas increased cell number made a significant contribution in the case of internodes which were relatively immature at the time the stimulus was applied. The progressive increase in internode length of both genotypes during ontogeny was due primarily to an increase in cell number. In conclusion, alleles cryc and crys (background le La) do not confer a difference in sensitivity to GA1 and the increase in internode length in response to incandescent light is probably not the result of a real or perceived increase in GA1 level. Allele crys may partially block a phytochrome mediated response to light and the key difference between genotypes crys and cryc may lie in the greater elongation (extensibility?) of cryc epidermal cells in incandescent light. 相似文献
17.
P. R. Patnaik 《Bioprocess and biosystems engineering》1995,13(2):109-112
Previous studies have shown that the rate of formation of streptokinase, a secondary metabolite, in batch fermentation is proportional to the specific growth rate of the biomass, which in turn is inhibited by its substrate and the primary product (lactic acid). These kinetics suggest the suitability of fed-batch operation to increase the yield of streptokinase. A near-optimal feed policy has been calculated by the chemotaxis algorithm, and it shows a substrate feed rate decreasing nonlinearly and vanishing after 11 hours. This is followed by batch fermentation for a further 8 hours, at the end of which 12% more streptokinase is generated than by purely batch fermentation. Further improvements in productivity are possible.List of Symbols
k
dh–1
decay constant for active cells
-
k
ph–1
decay constant for streptokinase
-
K
Igl–1
inhibition constant for lactic acid
- KS gl–1
inhibition constant for substrate
-
M gl–1
lactic acid concentration
-
P gl–1
streptokinase concentration
-
Q 1h–1
substrate feed rate
-
S gl–1
substrate concentration
-
S
ingl–1
inlet concentration of substrate
-
t h
time
-
t
bh
end-point of batch fermentation
-
t
fh
end-point of fed-batch fermentation
-
V l
volume of broth in fermenter
-
V
0 l
initial value of V (at t=0)
-
V
ml
maximum value of V
-
X gl–1
total biomass concentration
-
X
agl–1
concentration of active biomass
-
Y
MX
yield coefficient for lactic acid from biomass
-
Y
PX
yield coefficient for streptokinase from biomass
-
Y
XS
yield coefficient for biomass from substrate
Greek Letters
h–1
specific growth rate of biomass
-
mh–1
maximum specific growth rate 相似文献
18.
Joanna Kotyńska Izabela Dobrzyńska Zbigniew Artur Figaszewski 《Journal of bioenergetics and biomembranes》2008,40(6):637-641
We examined the effect of adsorbed monovalent ions on the surface charge of phosphatidylcholine (PC) – decylamine (DA) liposomal
membranes. Surface charge density values were determined from electrophoretic mobility measurements of lipid vesicles performed
at various pH levels. The interaction between solution ions and the PC-DA liposomal surface was described by a six component
equilibrium model. The previously determined association constants of the -PO(-) and –N(+)(CH3)3 groups of PC with H+, OH-, Na+ and Cl- ions (K
A1H, K
B1OH, K
A1Na, K
B1C1) were used to calculate K
B2OH, and K
B2C1, the association constants of the –N(+)H3 group of DA with OH- and Cl- ions, providing an experimental verification for the proposed model. 相似文献
19.
Yunguo Gong 《Molecular simulation》2013,39(12):970-979
In this study, by homology modelling and molecular dynamics (MD) simulation, models of l-stepholidine (l-SPD) activating the 5-HT1A and D1 receptors were constructed. In 100-ns MD simulations, the D1 and 5-HT1A receptors were activated by the partial agonist l-SPD, conforming with the global toggle switch activation model and the sequential activation model. The residues Y7.53 and Y5.58 swing significantly between different transmembrane (TM) domains after activation. Similarities between D1 and 5-HT1A included (1) the outward motion of TM-5; (2) the ionic lock was independent of the tilt of TM-6 and (3) there was an apparent bending of TM-6, and the ring of l-SPD formed strong π–π interactions with residue W6.48. Differences between the two included the following: (1) in 5-HT1A, l-SPD formed a hydrogen bond with Ala1725.46 of TM-5, and the intracellular end of TM-5 moved outward slowly; that hydrogen bond did not form with the D1 receptor; (2) l-SPD formed stronger interactions with D3.32 and W6.48 in the D1 receptor than in the 5-HT1A receptor and (3) the hydrogen bonding network was somewhat different in SPD-5-HT1A and SPD-D1 receptors. We propose the interaction between l-SPD and D3.32 or/and W6.48 is the original driving force during the whole activation process. 相似文献
20.
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