Localized inhibition of clindamycin-2-phosphate hydrolysis due to product inhibition by inorganic phosphate

1981 ◽  
Vol 7 (1) ◽  
pp. 101-104
Author(s):  
J.I. BLENKHARN ◽  
J.H. DARRELL
Keyword(s):  
Inorganic Phosphate ◽  
Product Inhibition ◽  
Phosphate Hydrolysis

scholarly journals Product inhibition studies on bovine liver carbamoyl phosphate synthetase

1974 ◽  
Vol 141 (3) ◽  
pp. 817-824 ◽  
Author(s):  
Keith R. F. Elliott ◽  
Keith F. Tipton
Keyword(s):  
Inorganic Phosphate ◽  
Substrate Binding ◽  
Inorganic Ions ◽  
Bovine Liver ◽  
Product Inhibition ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Product Release ◽  
Proposed Model ◽  
Inhibition Studies

A study of the product-inhibition patterns of carbamoyl phosphate synthetase from bovine liver is reported. Inhibition by adenosine, AMP and inorganic ions is also reported. The results are in agreement with the previously proposed model in which the order of substrate binding is ATPMg, followed by HCO3−, ATPMg and NH4+. The order of product release on the basis of the reported results is carbamoyl phosphate, followed by ADPMg, ADPMg and inorganic phosphate.

Alkaline phosphatases of Neurospora crassa. Part II product inhibition studies

1972 ◽  
Vol 18 (4) ◽  
pp. 407-421 ◽  
Author(s):  
F. W. J. Davis ◽  
Howard Lees
Keyword(s):  
Neurospora Crassa ◽  
Competitive Inhibitor ◽  
Product Inhibition ◽  
Nitrophenyl Phosphate ◽  
Wide Range ◽  
Phosphate Hydrolysis ◽  
Non Linear ◽  
Inhibition Studies ◽  
Enzyme Complexes ◽  
Hydrolysis Of

A partially purified preparation of the constitutive alkaline phosphatase from Neurospora crassa, containing two electrophoretically distinct activities was used in initial studies of product inhibition patterns. Inorganic phosphate was shown to be a linear competitive inhibitor, and p-nitrophenol to be a non-linear, non-competitive inhibitor of p-nitrophenyl phosphate hydrolysis. Glycerol was shown to be a linear non-competitive inhibitor of β-glycerophosphate hydrolysis.A purification procedure whereby one enzyme activity could be obtained free of the second was devised. The purified enzyme catalyzed the hydrolysis of a wide range of substrates and had a molecular weight of 111 000. Its hydrolysis of glucose 6-phosphate was competitively inhibited by phosphate and non-competitively inhibited by glucose. Both inhibitions were linear. Hydrolysis of p-nitrophenyl phosphate was competitively inhibited by phosphate in a linear manner, but p-nitrophenol was a non-linear, non-competitive inhibitor. Alternate product inhibition by glucose was linear competitive. No inhibition by p-nitrophenol of glucose 6-phosphate hydrolysis could be detected.The inhibition data for glucose 6-phosphate and β-glycerophosphate may be consistent with an ordered Uni-Bi mechanism expanded to include one or more isomerizations of enzyme complexes. The postulation of a different mechanism involving alternate pathways is probably required to explain the data obtained when p-nitrophenyl phosphate was the substrate.

Plasmalemma localisation of inorganic phosphate in B cells pancreas

1978 ◽  
Vol 36 (2) ◽  
pp. 528-529
Author(s):  
F. B. P. Wooding ◽  
K. Pedley ◽  
N. Freinkel ◽  
R. M. C. Dawson
Keyword(s):  
Electron Microscope ◽  
B Cells ◽  
B Cell ◽  
Pancreatic Islets ◽  
High Glucose ◽  
Lead Acetate ◽  
Inorganic Phosphate ◽  
Slight Modification ◽  
Uranyl Acetate ◽  
Lead Phosphate

Freinkel et al (1974) demonstrated that isolated perifused rat pancreatic islets reproduceably release up to 50% of their total inorganic phosphate when the concentration of glucose in the perifusion medium is raised.Using a slight modification of the Libanati and Tandler (1969) method for localising inorganic phosphate by fixation-precipitation with glutaraldehyde-lead acetate we can demonstrate there is a significant deposition of lead phosphate (identified by energy dispersive electron microscope microanalysis) at or on the plasmalemma of the B cell of the islets (Fig 1, 3). Islets after incubation in high glucose show very little precipitate at this or any other site (Fig 2). At higher magnification the precipitate seems to be intracellular (Fig 4) but since any use of osmium or uranyl acetate to increase membrane contrast removes the precipitate of lead phosphate it has not been possible to verify this as yet.

Relation between intravascular electrolyte level and course of parturition in dairy cows

2013 ◽  
Vol 41 (05) ◽  
pp. 289-296 ◽  
Author(s):  
K. Seyrek-Intas ◽  
K. Failing ◽  
G. Yilmazbas Mecitoglu ◽  
H. Bostedt ◽  
D. Seyrek-Intas
Keyword(s):  
Dairy Cows ◽  
Inorganic Phosphate ◽  
Post Partum ◽  
Total Calcium ◽  
Normal Delivery ◽  
P Values ◽  
Normal Birth ◽  
Factors Influencing ◽  
Electrolyte Homeostasis ◽  
Convalescence Phase

Summary Objective: To determine the intravascular electrolyte status in dairy cows with respect to age and different courses of parturition to clarify etiological factors influencing peri- or intrapartal imbalances of electrolyte homeostasis. Material and methods: A total of 64 cows at birth were evaluated (primiparous n = 34, pluriparous n = 30). Thirty-three cows showed normal delivery, while 31 cows had a complicated birth. Blood samples were collected intra partum (i. p.) and 2, 4, 6, 8, 12, 16, 24 h post partum (p. p.) as well as [2, 3, 4, 5, 7, 10 days p. p. and levels of total calcium (Catotal), ionized calcium (Caion), inorganic phosphate (Pa), Mg, Na, K, Cl were determined. Results: The results revealed that electrolytes show great fluctuation during and immediately p. p. in relation to age. Already during parturition pluriparous cows had a lower Catotal and Pa concentration compared to primiparous animals. Cows with dystocia exhibited a more intensive and longer lasting decrease of Ca compared to cows with normal birth. In relation to age and severity of birth Pa concentration showed a differing but basically typical course for this electrolyte. Mg, Na, K and Cl concentrations were higher during and immediately after birth compared to p. p. values. Until day 10 p. p. these electrolyte concentrations declined more in older cows with dystocia compared to younger animals. However, the influence of dystocia on concentration of these electrolytes was milder in contrast to Ca and Pa. Conclusions: In summary, primarily older cows are predisposed to imbalances of electrolyte homeostasis intra partum and at the beginning of the lactation. These changes are potentiated in case of complications during parturition. Intravascular Catotal, Caion as well as Pa are most severely affected. Clinical relevance: These results may constitute the basis for a comprehensive metaphylaxis during the peripartal period, especially in cows after dystocia, to positively influence the early convalescence phase.

Biomimetic Extracellular Vesicles Embedded with Black Phosphorus for Molecular Recognition-Guided Biomineralization

2018 ◽  
Author(s):  
Yingqian Wang ◽  
Xiaoxia Hu ◽  
Lingling Zhang ◽  
Chunli Zhu ◽  
Jie Wang ◽  
...  
Keyword(s):  
Molecular Recognition ◽  
Extracellular Vesicles ◽  
Inorganic Phosphate ◽  
Physiological Activity ◽  
Medical Engineering ◽  
Matrix Vesicles ◽  
Black Phosphorus ◽  
Photothermal Effect ◽  
Biological Processes ◽  
Extracellular Environment

Extracellular vesicles (EVs) are involved in the regulation of cell physiological activity and the reconstruction of extracellular environment. Matrix vesicles (MVs) are a type of EVs, and they participate in the regulation of cell mineralization. Herein, bioinspired MVs embedded with black phosphorus are functionalized with cell-specific aptamer (denoted as Apt-bioinspired MVs) for stimulating biomineralization. The aptamer can direct bioinspired MVs to targeted cells, and the increasing concentration of inorganic phosphate originated from the black phosphorus can facilitate cell biomineralization. The photothermal effect of the Apt-bioinspired MVs also positively affects mineralization. In addition, the Apt-bioinspired MVs display outstanding bone regeneration performance. Considering the excellent behavior of the Apt-bioinspired MVs for promoting biomineralization, our strategy provides a way of designing bionic tools for studying the mechanisms of biological processes and advancing the development of medical engineering.<br>

Correlative Study of Bone-Related Biochemicals and Endocrine Changes in Perimenopausal Women in Enugu, Nigeria.

2020 ◽  
Vol 23 ◽  
Author(s):  
Chinwe Ifeoma Ikegwuonu ◽  
Ikenna Kingsley Uchendu ◽  
Chukwudi Ignatius Maduka
Keyword(s):  
Inorganic Phosphate ◽  
Premenopausal Women ◽  
Positive Association ◽  
Biochemical Changes ◽  
Health Conditions ◽  
Hormonal Changes ◽  
Negatively Associated ◽  
Perimenopausal Women ◽  
Endocrine Parameters ◽  
Apparently Healthy

Background and Objective: Perimenopause is a physiological occurrence in women, and is characterized by endocrine and biochemical changes. During perimenopause phase, many derangements or abnormal health conditions start developing as a result of hormonal changes. These derangements in health conditions and biochemical changes lead to higher incidence of metabolic syndrome (MetS) occurrence with or without bone involvement. There is scarcity of information on MetS in Enugu, Southern Nigeria and there is no available data on the correlation of selected bone-related biochemicals with endocrine parameters and MetS in perimenopausal women from the region. Material and Methods: We consecutively sampled 200 apparently healthy women, and categorized them into 120 perimenopausal women (age ( Results: Calcium was predominantly high in the three criteria (p<0.05). LH and FSH showed positive correlation with FPG while E2 was negatively associated with FPG. Similarly LH showed positive association with inorganic phosphate while E2 was negatively associated with alkaline phosphatase (p<0.05). Conclusion: Perimenopausal women are at higher risk for developing osteoporosis than premenopausal women. This emphasizes the need for timely diagnosis of osteoporosis in perimenopausal women.

Diabetes, Diabetic Complications, and Phosphate Toxicity: A Scoping Review

2020 ◽  
Vol 16 (7) ◽  
pp. 674-689 ◽  
Author(s):  
Ronald B. Brown
Keyword(s):  
Scoping Review ◽  
Diabetic Complications ◽  
Inorganic Phosphate ◽  
Dietary Intervention ◽  
Neuronal Degeneration ◽  
Ectopic Calcification ◽  
Treatment And Prevention ◽  
Research Findings ◽  
Serum Inorganic Phosphate ◽  
Prevention Of Diabetes

This article presents a scoping review and synthesis of research findings investigating the toxic cellular accumulation of dysregulated inorganic phosphate—phosphate toxicity—as a pathophysiological determinant of diabetes and diabetic complications. Phosphorus, an essential micronutrient, is closely linked to the cellular metabolism of glucose for energy production, and serum inorganic phosphate is often transported into cells along with glucose during insulin therapy. Mitochondrial dysfunction and apoptosis, endoplasmic reticulum stress, neuronal degeneration, and pancreatic cancer are associated with dysregulated levels of phosphate in diabetes. Ectopic calcification involving deposition of calcium-phosphate crystals is prevalent throughout diabetic complications, including vascular calcification, nephropathy, retinopathy, and bone disorders. A low-glycemic, low-phosphate dietary intervention is proposed for further investigations in the treatment and prevention of diabetes and related diabetic pathologies.

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