scholarly journals A model study of the fructose diphosphatase–phosphofructokinase substrate cycle

1973 ◽  
Vol 134 (2) ◽  
pp. 581-586 ◽  
Author(s):  
David P. Bloxham ◽  
Michael G. Clark ◽  
Paul C. Holland ◽  
Henry A. Lardy
Keyword(s):  
Triose Phosphate Isomerase ◽  
Theoretical Treatment ◽  
Glucose Phosphate Isomerase ◽  
Triose Phosphate ◽  
Glucose Phosphate ◽  
Model Study

A fructose diphosphatase–phosphofructokinase substrate cycle has been reconstructed in vitro to provide a system that recycles fructose 6-phosphate and hydrolyses ATP to ADP and Pi. The concerted actions of glucose phosphate isomerase, phosphofructokinase, aldolase and triose phosphate isomerase catalysed the loss of 3H from [5-3H,U-14C]glucose 6-phosphate. This was used as the basis of a method for the estimation of the fructose diphosphatase–phosphofructokinase substrate cycle. For the reconstructed cycle, the rate of decrease of the 3H/14C ratio in [5-3H,U-14C]hexose 6-phosphate was proportional to the rate of fructose 6-phosphate substrate cycling. A detailed theoretical treatment of this relationship is developed, which enables the rate of substrate cycling to be determined in vivo.

scholarly journals Mode of action of α-chlorohydrin as a male anti-fertility agent. Inhibition of the metabolism of ram spermatozoa by α-chlorohydrin and location of block in glycolysis

1978 ◽  
Vol 170 (1) ◽  
pp. 23-37 ◽  
Author(s):  
Patricia D. C. Brown-Woodman ◽  
Hideo Mohri ◽  
Toshiko Mohri ◽  
Dai Suter ◽  
Ian G. White
Keyword(s):  
Dehydrogenase Activity ◽  
Recovery Period ◽  
Triose Phosphate Isomerase ◽  
Glycolytic Enzymes ◽  
Unexpected Finding ◽  
Glycolytic Intermediate ◽  
Enzyme Preparations ◽  
Triose Phosphate

1. The effect of α-chlorohydrin on the metabolism of glycolytic and tricarboxylate-cycle substrates by ram spermatozoa was investigated. The utilization and oxidation of fructose and triose phosphate were much more sensitive to inhibition by α-chlorohydrin (0.1–1.0mm) than lactate or pyruvate. Inhibition of glycolysis by α-chlorohydrin is concluded to be between triose phosphate and pyruvate formation. Oxidation of glycerol was not as severely inhibited as that of the triose phosphate. This unexpected finding can be explained in terms of competition between glycerol and α-chlorohydrin. A second, much less sensitive site, of α-chlorohydrin inhibition appears to be associated with production of acetyl-CoA from exogenous and endogenous fatty acids. 2. Measurement of the glycolytic intermediates after incubation of spermatozoal suspensions with 15mm-fructose in the presence of 3mm-α-chlorohydrin showed a ‘block’ in the conversion of glyceraldehyde 3-phosphate into 3-phosphoglycerate. α-Chlorohydrin also caused conversion of most of the ATP in spermatozoa into AMP. After incubation with 3mm-α-chlorohydrin, glyceraldehyde 3-phosphate dehydrogenase and triose phosphate isomerase activities were decreased by approx. 90% and 80% respectively, and in some experiments aldolase was also inhibited. Other glycolytic enzymes were not affected by a low concentration (0.3mm) of α-chlorohydrin. Loss of motility of spermatozoa paralleled the decrease in glyceraldehyde 3-phosphate dehydrogenase activity. α-Chlorohydrin, however, did not inhibit glyceraldehyde 3-phosphate dehydrogenase or triose phosphate isomerase in sonicated enzyme preparations when added to the assay cuvette. 3. Measurement of intermediates and glycolytic enzymes in ejaculated spermatozoa before, during and after injection of rams with α-chlorohydrin (25mg/kg body wt.) confirmed a severe block in glycolysis in vivo at the site of triose phosphate conversion into 3-phosphoglycerate within 24h of the first injection. Glyceraldehyde 3-phosphate dehydrogenase activity was no longer detectable and both aldolase and triose phosphate isomerase were severely inhibited. Spermatozoal ATP decreased by 92% at this time, being quantitatively converted into AMP. At 1 month after injection of α-chlorohydrin glycolytic intermediate concentrations returned to normal in the spermatozoa but ATP was still only 38% of the pre-injection concentration. Motility of spermatozoa was, however, as good as during the pre-injection period. The activity of the inhibited enzymes also returned to normal during the recovery period and 26 days after injection were close to pre-injection values. 4. An unknown metabolic product of α-chlorohydrin is suggested to inhibit glyceraldehyde 3-phosphate dehydrogenase and triose phosphate isomerase of spermatozoa. This results in a lower ATP content, motility and fertility of the spermatozoa. Glycidol was shown not to be an active intermediate of α-chlorohydrin in vitro.

Recent Advances in the Development of Triose Phosphate Isomerase Inhibitors as Antiprotozoal Agents

2021 ◽  
Vol 28 ◽  
Author(s):  
Lenci K. Vázquez-Jiménez ◽  
Antonio Moreno-Herrera ◽  
Alfredo Juárez-Saldivar ◽  
Alonzo González-González ◽  
Eyra Ortiz-Pérez ◽  
...  
Keyword(s):  
Trichomonas Vaginalis ◽  
Tertiary Structure ◽  
Triose Phosphate Isomerase ◽  
Interfacial Region ◽  
Parasitic Diseases ◽  
Binding Modes ◽  
Design Strategies ◽  
Triose Phosphate ◽  
Glycolysis Pathway

Background: Parasitic diseases caused by protozoa such as Chagas disease, leishmaniasis, malaria, African trypanosomiasis, amebiasis, trichomoniasis, and giardiasis are considered serious public health problems in developing countries. Drug-resistance among parasites justifies the search for new therapeutic drugs and the identification of new targets becomes a valuable approach. In this scenario, glycolysis pathway which consists of the conversion of glucose into pyruvate plays an important role in the protozoa energy supply and it is therefore considered as a promising target. In this pathway, triose phosphate isomerase (TIM) plays an essential role in efficient energy production. Furthermore, protozoa TIM show structural differences with human enzyme counterparts suggesting the possibility of obtaining selective inhibitors. Therefore, TIM is considered a valid approach to develop new antiprotozoal agents, inhibiting the glycolysis in the parasite. Objective: In this review, we discuss the drug design strategies, structure-activity relationship, and binding modes of outstanding TIM inhibitors against Trypanosoma cruzi, Trypanosoma brucei, Plasmodium falciparum, Giardia lamblia, Leishmania mexicana, Trichomonas vaginalis, and Entamoeba histolytica. Results: TIM inhibitors showed mainly aromatic systems and symmetrical structure, where the size and type of heteroatom are important for enzyme inhibition. This inhibition is mainly based on the interaction with i) the interfacial region of TIM inducing changes on the quaternary and tertiary structure or ii) with the TIM catalytic region were the main pathways that disabled the catalytic activity of the enzyme. Conclusion: Benzothiazole, benzoxazole, benzimidazole, and sulfhydryl derivatives stand out as TIM inhibitors. In silico and in vitro studies demonstrate that the inhibitors bind mainly at the TIM dimer interface. In this review, the development of new TIM inhibitors as antiprotozoal drugs is demonstrated as an important pharmaceutical strategy that may lead to new therapies for these ancient parasitic diseases.

Investigation of the determinative state of the mouse inner cell mass

Development ◽  
1975 ◽  
Vol 33 (4) ◽  
pp. 979-990
Author(s):  
J. Rossant
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
In Utero ◽  
Glucose Phosphate Isomerase ◽  
Trophoblast Cells ◽  
Electrophoretic Variants ◽  
Glucose Phosphate

Inner cell masses (ICMs) were dissected from 3½- and 4½-day blastocysts and cultured in contact with 2½-day morulae. Blastocysts and morulae were homozygous for different electrophoretic variants of the enzyme glucose phosphate isomerase (GPI). Aggregation of ICMs and morulae was observed, and such aggregates were able to form blastocysts in vitro and morphologically normal foetuses in utero. GPI analysis of these conceptuses revealed that most were chimaeric. However, donor ICM-type isozyme was only detected in the embryonic and extra-embryonic fractions of the chimaeras and never in the trophoblastic fraction. Thus, ICM cells appear unable to form trophoblast derivatives even when exposed to ‘outside’ conditions as experienced by developing trophoblast cells. This is evidence that ICM cells, although not overtly differentiated, are determined by 3½ days.

Studies in Cranial Suture Biology: In Vitro Cranial Suture Fusion

1996 ◽  
Vol 33 (2) ◽  
pp. 150-156 ◽  
Author(s):  
James P. Bradley ◽  
Jamie P. Levine ◽  
Christopher Blewett ◽  
Thomas Krummel ◽  
Joseph G. Mccarthy ◽  
...  
Keyword(s):  
Organ Culture ◽  
In Vitro Model ◽  
In Vitro Study ◽  
Cranial Base ◽  
Cranial Suture ◽  
Model Study ◽  
Suture Fusion ◽  
Vitro Model

The biology underlying craniosynostosis remains unknown. Previous studies have shown that the underlying dura mater, not the suture itself, signals a suture to fuse. The purpose of this study was to develop an in vitro model for cranial-suture fusion that would still allow for suture-dura interaction, but without the influence of tensional forces transmitted from the cranial base. This was accomplished by demonstrating that the posterior frontal mouse cranial suture, known to be the only cranial suture that fuses in vivo, fuses when plated with its dura in an organ-culture system. In such an organ-culture system, the sutures are free from both the influence of dural forces transmitted from the cranial base and from hormonal influences only available in a perfused system. For the cranial-suture fusion in vitro model study, the sagittal sutures (controls that remain patent in vivo) and posterior frontal sutures (that fuse in vivo) with the underlying dura were excised from 24-day-old euthanized mice, cut into 5 × 4 × 2-mm specimens, and cultured in a chemically defined, serum-free media. One hundred sutures were harvested at the day of sacrifice, then every 2 days thereafter until 30 days in culture, stained with H & E, and analyzed. A subsequent cranial-suture without dura in vitro study was performed in a similar fashion to the first study, but only the calvariae with the posterior frontal or sagittal sutures (without the underlying dura) were cultured. Results from the cranial-suture fusion in vitro model study showed that all sagittal sutures placed in organ culture with the underlying dura remained patent. More importantly, the posterior frontal sutures with the underlying dura, which were plated-down as patent at 24 days of age, demonstrated fusion after various growth periods in organ culture. In vitro posterior frontal mouse-suture fusion occurred in an anterior-to-posterior direction but in a delayed fashion, 4 to 7 days later than in vivo posterior frontal mouse-suture fusion. In contrast, the subsequent cranial-suture without dura in vitro study showed patency of all sutures, including the posterior frontal suture. These data from in vitro experiments indicate that: (1) mouse calvariae, sutures, and the underlying dura survive and grow in organ-culture systems for 30 days; (2) the local dura, free from external influences transmitted from the cranial base and hormones from distant sites, influences the cells of its overlying suture to cause fusion; and (3) without dura influence, all in vitro cranial sutures remained patent. By first identifying the factors involved in dural-suture signaling and then regulating these factors and their receptors, the biologic basis of suture fusion and craniosynostosis may be unraveled and used in the future to manipulate pathologic (premature) suture fusion.

scholarly journals The Novel Transcription Factor SgrR Coordinates the Response to Glucose-Phosphate Stress

2007 ◽  
Vol 189 (6) ◽  
pp. 2238-2248 ◽  
Author(s):  
Carin K. Vanderpool ◽  
Susan Gottesman
Keyword(s):  
Binding Site ◽  
Binding Domain ◽  
Alternative Mechanism ◽  
Gene Encoding ◽  
Bacterial Transcription ◽  
Glucose Phosphate ◽  
Plasmid Library ◽  
Promoter Dna

ABSTRACT SgrR is the first characterized member of a family of bacterial transcription factors containing an N-terminal DNA binding domain and a C-terminal solute binding domain. Previously, we reported genetic evidence that SgrR activates the divergently transcribed gene sgrS, which encodes a small RNA required for recovery from glucose-phosphate stress. In this study, we examined the regulation of sgrR expression and found that SgrR negatively autoregulates its own transcription in the presence and absence of stress. An SgrR binding site in the sgrR-sgrS intergenic region is required in vivo for both SgrR-dependent activation of sgrS and autorepression of sgrR. Purified SgrR binds specifically to sgrS promoter DNA in vitro; a mutation in the site required for in vivo activation and autorepression abrogates in vitro SgrR binding. A plasmid library screen identified clones that alter expression of a P sgrS -lacZ fusion; some act by titrating endogenous SgrR. The yfdZ gene, encoding a putative aminotransferase, was identified in this screen; the yfdZ promoter contains an SgrR binding site, and transcriptional fusions indicate that yfdZ is activated by SgrR. Clones containing mlc, which encodes a glucose-specific repressor protein, also downregulate P sgrS -lacZ. The mlc clones do not appear to titrate the SgrR protein, indicating that Mlc affects sgrS expression by an alternative mechanism.

scholarly journals Glycolytic enzymes in mammalian spermatozoa. Activities and stabilities of hexokinase and phosphofructokinase in various fractions from sperm homogenates

1971 ◽  
Vol 124 (4) ◽  
pp. 741-750 ◽  
Author(s):  
R. A. P. Harrison
Keyword(s):  
Thiol Group ◽  
Published Data ◽  
Glucose Phosphate Isomerase ◽  
Cytoplasmic Material ◽  
Phosphate Ions ◽  
Glucose Phosphate ◽  
Homogenization Methods ◽  
Ram Sperm ◽  
Mammalian Spermatozoa

1. Methods of homogenizing suspensions of washed mammalian spermatozoa were studied. The most useful methods were those using sonication and those using a French press. 2. Hexokinase, phosphofructokinase, glucose phosphate isomerase and adenosine triphosphatase activities in ram, bull and boar spermatozoa were investigated by using these two homogenization methods. Glucose phosphate isomerase, representative of soluble cytoplasmic material, was very readily extracted and remained entirely in the supernatant after centrifugation at 145000g for 60min. In contrast, the other three activities were less easily extracted and were sedimented in various proportions under the described conditions of centrifugation. 3. Attempts to obtain subcellular fractions from sperm homogenates by ‘classical’ methods failed, owing apparently to the inhomogeneity of subcellular particles in the homogenates. It is concluded that, after removal of sperm heads, the only meaningful fractionation is a separation of spermatozoal material which sediments at 145000g during 60min from that which does not. 4. The stabilities of hexokinase and phosphofructokinase activities in bull, boar and ram sperm homogenates were investigated. Hexokinases showed very little dependence on the various environments tested, whereas the optimum conditions for phosphofructokinase stability were: a minimum of sonication, the presence of phosphate ions and of a thiol-group protectant, and a pH7.5. Activities of hexokinase, phosphofructokinase and glucose phosphate isomerase per sperm cell were compared with published data on rates of fructolysis by spermatozoa; the potential catalytic activities were shown to be considerably in excess of these rates. However, phosphofructokinase may be the rate-limiting enzyme of glycolysis in vivo in bull and ram spermatozoa.

scholarly journals Nuclear transfer from teratocarcinoma cells into mouse oocytes and eggs

Development ◽  
1990 ◽  
Vol 108 (2) ◽  
pp. 337-348
Author(s):  
J.A. Modlinski ◽  
D. Gerhauser ◽  
B. Lioi ◽  
H. Winking ◽  
K. Illmensee
Keyword(s):  
Embryonal Carcinoma ◽  
Preimplantation Embryos ◽  
Time Intervals ◽  
Electrophoretic Variants ◽  
Glucose Phosphate ◽  
Teratocarcinoma Cells ◽  
Nuclear Transplant ◽  
Ec Cells

A spontaneous ovarian teratocarcinoma was isolated from a LT/Sv mouse female and converted into an ascites tumor from which embryonal carcinoma (EC) cells were dissociated. Non-enucleated and enucleated, activated oocytes were fused with EC cells and either cultured in vitro or transferred into ligated oviducts of Swiss/A females. The nucleocytoplasmic hybrids cultured in vitro up to 22 h were examined cytologically at various time intervals. EC nuclei showed morphological remodelling in the foreign cytoplasm. EC chromosomes and female pronuclear chromosomes together formed a common metaphase. The nucleocytoplasmic hybrids developed in vivo were analyzed cytologically between the first and third day after oviduct transfer. The majority of embryos developed abnormally and, in a few instances, they had passed several cleavage divisions and reached, at best, a developmental stage resembling a premature morula. Fertilized, enucleated eggs were fused with EC cells or microinjected with EC nuclei. The resulting nucleocytoplasmic hybrids were either cultured in vitro or in vivo up to the fourth day. Enzyme tests were carried out on the nuclear transplant embryos, using electrophoretic variants of glucose phosphate isomerase (GPI) in order to distinguish between EC nuclei (GPI-A) and recipient eggs (GPI-B). The EC-specific GPI could be detected in about one third of the embryos analyzed and, in several instances, also together with the egg-specific GPI. Most of them were arrested during early cleavage divisions. Some embryos cleaved abnormally or mimicked normal embryogenesis. In a few instances, development resulted in embryos that resembled late preimplantation embryos.

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