scholarly journals Aldehyde oxidation in human placenta. Purification and properties of 1-pyrroline-5-carboxylate dehydrogenase

1988 ◽  
Vol 256 (2) ◽  
pp. 461-467 ◽  
Author(s):  
J Farrés ◽  
P Julià ◽  
X Parés
Keyword(s):  
Human Placenta ◽  
Deae Cellulose ◽  
Physiological Role ◽  
Total Activity ◽  
Molar Ratio ◽  
Distribution Study ◽  
Purification And Properties ◽  
Highly Sensitive ◽  
Aldehyde Oxidation

The human placenta contains a considerable amount of 1-pyrroline-5-carboxylate dehydrogenase (23 +/- 6 micrograms/g; n = 12), about 25% of the concentration present in liver. The enzyme is the only form in placenta that oxidizes short- and medium-chain aldehydes, which facilitates its purification from this organ. It can be purified to homogeneity by successive chromatographies on DEAE-cellulose, 5′-AMP-Sepharose and Sephacryl S-300. From 500 g of tissue, about 2.1 units of enzyme can be obtained with a 12% yield. Placental 1-pyrroline-5-carboxylate dehydrogenase is a dimer of Mr-63,000 subunits. It exhibits a pI of 6.80-6.65, and is specific for 1-pyrroline-5-carboxylate, the cyclic form of glutamate gamma-semialdehyde (Km = 0.17 mM, kcat. = 870 min-1), although it also oxidizes short-chain aliphatic aldehydes such as propionaldehyde (Km = 24 mM, kcat. = 500 min-1). These properties are very close to those of the liver enzyme, indicating a strong similarity between the enzyme forms from both organs. The enzyme is highly sensitive to temperature, showing 50% inhibition after incubation for 0.8 min at 45 degrees C or after 23 min at 25 degrees C. It is irreversibly inhibited by disulfiram, and a molar ratio inhibitor: enzyme of 60:1 produced 50% inhibition after incubation for 10 min. A subcellular-distribution study indicates that the enzyme is located in two compartments: the mitochondria, with 60% of the total activity, and the cytosol, with 40% activity. The physiological role of the enzyme in placental amino acid metabolism is discussed.

scholarly journals Interphotoreceptor coupling: an evolutionary perspective

2021 ◽  
Author(s):  
Lorenzo Cangiano ◽  
Sabrina Asteriti
Keyword(s):  
Visual Information ◽  
Signal To Noise Ratio ◽  
Electrical Coupling ◽  
Physiological Role ◽  
Cellular Processes ◽  
Contact Points ◽  
Highly Sensitive ◽  
The Many ◽  
The Impact

AbstractIn the vertebrate retina, signals generated by cones of different spectral preference and by highly sensitive rod photoreceptors interact at various levels to extract salient visual information. The first opportunity for such interaction is offered by electrical coupling of the photoreceptors themselves, which is mediated by gap junctions located at the contact points of specialised cellular processes: synaptic terminals, telodendria and radial fins. Here, we examine the evolutionary pressures for and against interphotoreceptor coupling, which are likely to have shaped how coupling is deployed in different species. The impact of coupling on signal to noise ratio, spatial acuity, contrast sensitivity, absolute and increment threshold, retinal signal flow and colour discrimination is discussed while emphasising available data from a variety of vertebrate models spanning from lampreys to primates. We highlight the many gaps in our knowledge, persisting discrepancies in the literature, as well as some major unanswered questions on the actual extent and physiological role of cone-cone, rod-cone and rod-rod communication. Lastly, we point toward limited but intriguing evidence suggestive of the ancestral form of coupling among ciliary photoreceptors.

scholarly journals Regulation of nitric oxide synthase isoforms and role of nitric oxide during prostaglandin F2alpha-induced luteolysis in rabbits

Reproduction ◽  
2003 ◽  
pp. 807-816 ◽  
Author(s):  
C Boiti ◽  
G Guelfi ◽  
D Zampini ◽  
G Brecchia ◽  
A Gobbetti ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Time Course ◽  
Plasma Concentrations ◽  
Physiological Role ◽  
Total Activity ◽  
Corpora Lutea ◽  
Prostaglandin F ◽  
Oxide Synthase

Total activity of nitric oxide synthase (NOS) and the gene expression of both endothelial NOS (eNOS) and inducible NOS (iNOS) isoforms in corpora lutea of pseudopregnant rabbits were examined during prostaglandin F(2alpha) (PGF(2alpha))-induced luteolysis. Corpora lutea were collected at 0, 6, 12, 24 and 48 h after an injection of PGF(2alpha) at day 9 of pseudopregnancy. At 12 h after PGF(2alpha) administration, luteal mRNA encoding eNOS decreased (P0.05) by 40% and remained low throughout the subsequent 36 h, whereas eNOS protein increased (P0.05) two- to threefold. By contrast, expression of mRNA encoding iNOS was poor and remained fairly constant, but transcription increased eightfold (P0.01) within 6 h after PGF(2alpha) treatment and then decreased to values similar to those of controls. Total NOS activity increased twofold (P0.01) at 6 h after treatment and remained high thereafter, whereas progesterone concentrations in explanted corpora lutea decreased (P0.01) from 302.4+/-42.3 pg x mg(-1) at day 9 to 58.6+/-8.3 at 48 h later, and peripheral plasma concentrations of progesterone declined too. Long-term administration of Nomega-nitro-L-arginine methyl ester (0.6 g l(-1) per os) from day 2 of pseudopregnancy onward partially blocked the luteolytic action of PGF(2alpha) administered at day 9 of pseudopregnancy. In nitric oxide (NO)-deficient rabbits, progesterone concentrations remained higher (P0.01) than in controls at 24-48 h after PGF(2alpha) administration (4.5 to 3.2 ng x ml(-1), respectively). These data are the first to characterize NOS activity. The time course of expression of eNOS and iNOS in rabbit corpora lutea during PGF(2alpha)-induced luteolysis gives additional support to a physiological role of NO in the regulation of regression of corpora lutea in rabbits.

ISOLATION OF cDNA FOR TYPE-2 PLASMINOGEN ACTIVATOR INHIBITOR

1987 ◽  
Author(s):  
T Ny ◽  
L Hansson ◽  
B Åstedt
Keyword(s):  
Monoclonal Antibody ◽  
Plasminogen Activator ◽  
Human Placenta ◽  
Physiological Role ◽  
Plasminogen Activator Inhibitor ◽  
Expression Library ◽  
Type Plasminogen Activator ◽  
Sds Page ◽  
Activator Inhibitor

The placental type plasminogen activator inhibitor (PAI-2) has been purified from extracts of human placenta and from a histiocytic lymphoma cell line. It is mainly an uPA inhibitor but it also inhibits the two-chain form of tPA.In order to determine the factors regulating PAI-2 gene expression and thereby clarify the physiological role of PAI-2 we have undertaken the molecular cloning of PAI-2 cDNA. A λgt11 expression library prepared from placental mRNA, was screened, immunologically using a monoclonal antibody probe developed against PAI-2 purified from human placenta. When 1.7×105 recombinant phages were screened six positive clones were obtained. Hybridization experiments and comparison of restriction enzyme cleavege pattern revealed that the DNA inserts of the six clones were, related. To identify the clones as coding for PAI-2, a lysogen made from one of them was induced, and the proteins were separated by SDS-PAGE. In immuno-blotting wxperiments the recombinant fusion protein and purified PAI-2 were recognized by the monoclonal antibody and a monospecific polyclonal antibody against PAI-2, revealing an immunological similarity. The nucleotide sequence of the largest cDNA was determined. It was found to code for a protein with extensive sequence homology with members of the serine protease inhibitor family (serpins) Alignment of the active center region with other serpins indicates that PAI-2 is an arg-serpin, as expected for an inhibitor of plasminogen activators.

scholarly journals β-Fructofuranosidases from roots of dandelion (Taraxacum officinale Weber)

1972 ◽  
Vol 126 (3) ◽  
pp. 569-573 ◽  
Author(s):  
P. P. Rutherford ◽  
A. C. Deacon
Keyword(s):  
General Formula ◽  
Soluble Protein ◽  
Hydrolytic Enzymes ◽  
Deae Cellulose ◽  
Physiological Role ◽  
Taraxacum Officinale ◽  
The Other ◽  
Ph Optimum ◽  
Cellulose Column

1. Three β-fructofuranosidases were separated by chromatography on a DEAE-cellulose column from the soluble protein extracted from dandelion (Taraxacum officinale Weber) roots. 2. One enzyme, which acted on sucrose, was characterized as an invertase, with a Km of 2.00×10-2M and pH optimum of 7.5. 3. The other two enzymes are hydrolases (A and B), which act on the inulin series of oligosaccharides [general formula glucose-fructose-(fructose)n]. They both have a pH optimum of 4.0 and Km of 1.54×10-2M but differ in their chromatographic behaviour on DEAE-cellulose. Neither of the hydrolases is inhibited by sucrose. 4. The physiological role of these three hydrolytic enzymes is discussed.

The Activation of Human Factor X in Sodium Citrate: the Role of Factor VII

1976 ◽  
Vol 36 (01) ◽  
pp. 104-114 ◽  
Author(s):  
D. L Aronson ◽  
A. J Mustafa
Keyword(s):  
Sodium Citrate ◽  
Human Factor ◽  
Deae Cellulose ◽  
Factor Ix ◽  
Factor Vii ◽  
Factor X

SummaryHuman factor X was purified by several different procedures yielding products which had varying amounts of factor VII and factor IX. Treatment with CHC13 during the fractionation of the factor X removed 95% of the factor VII and factor IX activity and the resulting factor X activated more slowly when incubated in 25% sodium citrate. Removal of residual factor VII by DEAE cellulose chromatography yielded a factor X which activated still more slowly and less completely. When the factor VII, removed by chromatography, was added to the chromatographed factor X, the ability to be activated in 25% sodium citrate was restored. Confirmatory evidence for the role of factor VII in this reaction was the inhibition of the conversion of the factor X by both DFP and SBTI.

Highly sensitive adolescent benefits in positive school transitions: Evidence for vantage sensitivity in Japanese high-schoolers

2020 ◽  
Author(s):  
Shuhei Iimura
Keyword(s):  
High School ◽  
Statistical Power ◽  
Environmental Influences ◽  
Differential Susceptibility ◽  
School Transition ◽  
Well Being ◽  
Crossover Point ◽  
Japanese Adolescents ◽  
Highly Sensitive

Some researchers indicate that the transition to high school deflects adolescent developmental trajectories. Others assert it provides a new possibility for the promotion of adolescents’ socioemotional well-being. One critical view missing in such claims is that individual variabilities interact with environmental influences. We employed the framework of Differential Susceptibility Theory, which postulates that individual susceptibilities moderate external influences for better and for worse. In order to clarify the mechanism of adolescents’ differential adjustments, this paper investigated the role of sensory-processing sensitivity using the Japanese version of Highly Sensitive Child Scale for Adolescence (J-HSCS), and tested whether the diathesis-stress model or the differential susceptibility model best describes students’ socioemotional adjustment across their high school transition. The current paper used the two-wave data collected from Japanese adolescents aged from 14 to 15 years (n = 412, 50% girls). In Study 1, we investigated the replicability of psychometric properties of J-HSCS. The results supported previous findings, indicating its validity for the bifactor model. In Study 2, we utilized confirmatory competitive model testing, which maximizes statistical power by parameterizing the crossover point to allow a direct comparison of alternative models. The results indicated that neither the diathesis-stress nor the differential susceptibility models fitted the data. Rather, a strong vantage sensitivity model was revealed, suggesting that highly susceptible adolescents disproportionately benefitted from a positive school transition over their counterparts. This finding signified the role of adolescents’ sensitivity to environmental influences and the importance of considering its moderation under person x environment interactions.

Physiological Role of Cyclic Electron Flow in Higher Plants

2012 ◽  
Vol 30 (1) ◽  
pp. 100
Author(s):  
Wei HUANG ◽  
Shi-Bao ZHANG ◽  
Kun-Fang CAO
Keyword(s):  
Higher Plants ◽  
Electron Flow ◽  
Physiological Role ◽  
Cyclic Electron Flow
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