scholarly journals Studies on ram acrosin. Isolation from spermatozoa, activation by cations and organic solvents, and influence of cations on its reaction with inhibitors

1975 ◽  
Vol 149 (1) ◽  
pp. 133-146 ◽  
Author(s):  
Colin R. Brown ◽  
Zarina Andani ◽  
Edward F. Hartree
Keyword(s):  
Conformational Changes ◽  
Water Soluble ◽  
Dimethyl Sulphoxide ◽  
Soluble Form ◽  
Simple Method ◽  
Acrosomal Membrane ◽  
Low Concentrations ◽  
Kunitz Inhibitor ◽  
Pancreatic Trypsin Inhibitor ◽  
Acrosin Activity

1. A simple method is given for isolating from ram spermatozoa a water-soluble form of acrosin (a trypsin-like enzyme) which is about 25% pure. It is free from an acrosin inhibitor which is located in the spermatozoa. 2. In the hydrolysis of N-α-benzoyl-l-arginine ethyl ester the degree of activation of acrosin by Ca2+, and by some other cations, is dependent on the extent of contamination by the inhibitor. In 50mm-Tris–HCl buffer (pH8.2) activation by Ca2+ did not exceed 40%, but acrosin that is partially inhibited may be activated by up to 300%: this is due to cation-mediated protection of acrosin against the inhibitor. 3. Increasing concentrations of buffers (e.g. Tris) also activate acrosin but at above certain buffer concentrations Ca2+ no longer exerts an activating effect and may become inhibitory. Ca2+ is also inhibitory when added to assay systems involving anionic buffers with chelating properties. This is due to a fall in pH. 4. The above results suggest reasons for conflicting conclusions in papers dealing with the effects of Ca2+ on acrosin activity. 5. Inhibition of acrosin by the Kunitz pancreatic trypsin inhibitor is increased on addition of Ca2+. Inhibitions of trypsin by the acrosin inhibitor and by the Kunitz inhibitor are insensitive to Ca2+. 6. Like trypsin, acrosin is activated, up to 60%, by 2-methyl-propan-2-ol, dimethyl sulphoxide, and some other water-miscible solvents. Effects of cations and solvents tend to be additive and a common maximum acrosin activity can be achieved with various concentrations of solvent, salts and buffer in the assay system. Activation by solvents is increased when low concentrations of the acrosin inhibitor are present. 7. Activations of acrosin by salts and by solvents are more pronounced when the substrate is N-α-benzoyl-dl-arginine 2-naphthylamide. 8. Km values for ram acrosin (about 0.2mm) are much higher than those for trypsin, and kcat. values are slightly higher than those for trypsin. Considerations of the influences of ions and dimethyl sulphoxide on the activities and kinetic constants of acrosin and trypsin suggest that conformational changes are the factors mainly responsible for the reported activations of acrosin. 9. The following conclusions are reached. (a) Acrosin plays a role in the penetration of the sperm cell into the egg without becoming detached from the acrosomal membrane. (b) The enzyme is a peripheral membrane protein which may be classed as a cathepsin. (c) The susceptibility of the activity of soluble acrosin to cations and solvents points to a flexible molecule, i.e. one lacking conformational restraints imposed by association (presumably ionic) with the acrosomal membrane.

scholarly journals Conformational changes in gastric mucoproteins induced by caesium chloride and guanidinium chloride

1974 ◽  
Vol 141 (3) ◽  
pp. 641-646 ◽  
Author(s):  
David Snary ◽  
Adrian Allen ◽  
Roger H. Pain
Keyword(s):  
Molecular Weight ◽  
Conformational Changes ◽  
Sedimentation Coefficient ◽  
Water Structure ◽  
Water Soluble ◽  
Native Conformation ◽  
Guanidinium Chloride ◽  
Gastric Mucus ◽  
Caesium Chloride ◽  
Low Concentrations

1. Caesium chloride and guanidinium chloride were shown to cause conformational changes in the high-molecular-weight mucoprotein A of water-soluble gastric mucus with no change in molecular weight. 2. Increasing concentrations of CsCl decrease the viscosity of the mucoprotein bringing about a transition which is essentially complete in 0.1m-CsCl. The shear-dependence of viscosity of the mucoprotein is abolished by low concentrations of CsCl. The normally highly expanded molecule becomes contracted in CsCl to a molecule having the same symmetry but a smaller volume and decreased solvation, in keeping with an increased sedimentation coefficient (18.7S→33S). 3. This contracted form does not revert to the native conformation on removal of the CsCl. 4. A mechanism is discussed in terms of the effect of the Cs+and Cl−ions on water structure and the water–mucoprotein interaction. 5. Guanidinium chloride causes the CsCl-treated material to expand, in keeping with a decrease in s025,w (33S→26S). This is analogous to the known unfolding effect of guanidinium chloride on proteins and suggests that guanidinium chloride solubilizes groups involved in stabilizing the contracted structure. Removal of the guanidinium chloride results in a limited aggregation of four mucoprotein molecules. 6. These results show that caution must be exercised before interpreting the physical properties of mucoproteins which have been treated with CsCl and/or guanidinium chloride.

scholarly journals The Effect of Extraction Conditions on the Barrier and Mechanical Properties of Kefiran Films

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 602
Author(s):  
Carmen Rodica Pop ◽  
Teodora Emilia Coldea ◽  
Liana Claudia Salanţă ◽  
Alina Lăcrămioara Nistor ◽  
Andrei Borşa ◽  
...  
Keyword(s):  
Water Vapor ◽  
Conformational Changes ◽  
Water Vapor Permeability ◽  
Edible Films ◽  
Film Structure ◽  
Water Soluble ◽  
Vapor Permeability ◽  
Water Molecules ◽  
Compact Structure ◽  
Technology Applications

Kefiran is an exopolysaccharide classified as a heteropolysaccharide comprising glucose and galactose in equimolar quantities, and it is classified as a water-soluble glucogalactan. This work aimed to investigate the effect of different extraction conditions of kefiran on the structural and physical properties of the edible films obtained. Fourier-transform infrared spectroscopy and scanning electron microscopy were performed, together with a determinations of moisture content, solubility, water vapor permeability and degree of swelling. The kefiran films presented values of the water vapor permeability between 0.93 and 4.38 × 10−11 g/m.s.Pa. These results can be attributed to the development of a more compact structure, where glycerol had no power to increase the free volume and the water vapor diffusion through their structure. The possible conformational changes in the kefiran film structure, due to the interspersing of the plasticizers and water molecules that they absorb, could be the reason for producing flexible kefiran films in the case of using glycerol as a plasticizer at 7.5% w/w. Moreover, it was observed that the extraction conditions are a significant factor in the properties of these films and their food technology applications.

scholarly journals Analyzing the Carotenoid Composition of Melilot (Melilotus officinalis (L.) Pall.) Extracts and the Effects of Isolated (All-E)-lutein-5,6-epoxide on Primary Sensory Neurons and Macrophages

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 503
Author(s):  
Györgyi Horváth ◽  
Eszter Csikós ◽  
Eichertné Violetta Andres ◽  
Tímea Bencsik ◽  
Anikó Takátsy ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Sensory Neurons ◽  
Biological Activities ◽  
Water Soluble ◽  
Soluble Form ◽  
Primary Sensory Neurons ◽  
Isolation And Identification ◽  
Melilotus Officinalis ◽  
Carotenoid Composition ◽  
Anti Inflammatory

Melilotus officinalis is known to contain several types of secondary metabolites. In contrast, the carotenoid composition of this medicinal plant has not been investigated, although it may also contribute to the biological activities of the drug, such as anti-inflammatory effects. Therefore, this study focuses on the isolation and identification of carotenoids from Meliloti herba and on the effect of isolated (all-E)-lutein 5,6-epoxide on primary sensory neurons and macrophages involved in nociception, as well as neurogenic and non-neurogenic inflammatory processes. The composition of the plant extracts was analyzed by high performance liquid chromatography (HPLC). The main carotenoid was isolated by column liquid chromatography (CLC) and identified by MS and NMR. The effect of water-soluble lutein 5,6-epoxide-RAMEB (randomly methylated-β-cyclodextrin) was investigated on Ca2+-influx in rat primary sensory neurons induced by the activation of the transient receptor potential ankyrin 1 receptor agonist to mustard-oil and on endotoxin-induced IL-1β release from isolated mouse peritoneal macrophages. (all-E)-Lutein 5,6-epoxide significantly decreased the percent of responsive primary sensory neurons compared to the vehicle-treated stimulated control. Furthermore, endotoxin-evoked IL-1β release from macrophages was significantly decreased by 100 µM lutein 5,6-epoxide compared to the vehicle-treated control. The water-soluble form of lutein 5,6-epoxide-RAMEB decreases the activation of primary sensory neurons and macrophages, which opens perspectives for its analgesic and anti-inflammatory applications.

scholarly journals Human Lanosterol 14-Alpha Demethylase (CYP51A1) Is a Putative Target for Natural Flavonoid Luteolin 7,3′-Disulfate

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2237
Author(s):  
Leonid Kaluzhskiy ◽  
Pavel Ershov ◽  
Evgeniy Yablokov ◽  
Tatsiana Shkel ◽  
Irina Grabovec ◽  
...  
Keyword(s):  
Cholesterol Metabolism ◽  
Cholesterol Biosynthesis ◽  
Clinical Importance ◽  
Optical Biosensor ◽  
Water Soluble ◽  
Soluble Form ◽  
Redox Partner ◽  
Access Channel ◽  
Kd Values ◽  
Key Steps

Widespread pathologies such as atherosclerosis, metabolic syndrome and cancer are associated with dysregulation of sterol biosynthesis and metabolism. Cholesterol modulates the signaling pathways of neoplastic transformation and tumor progression. Lanosterol 14-alpha demethylase (cytochrome P450(51), CYP51A1) catalyzes one of the key steps in cholesterol biosynthesis. The fairly low somatic mutation frequency of CYP51A1, its druggability, as well as the possibility of interfering with cholesterol metabolism in cancer cells collectively suggest the clinical importance of CYP51A1. Here, we show that the natural flavonoid, luteolin 7,3′-disulfate, inhibits CYP51A1 activity. We also screened baicalein and luteolin, known to have antitumor activities and low toxicity, for their ability to interact with CYP51A1. The Kd values were estimated using both a surface plasmon resonance optical biosensor and spectral titration assays. Unexpectedly, in the enzymatic activity assays, only the water-soluble form of luteolin—luteolin 7,3′-disulfate—showed the ability to potently inhibit CYP51A1. Based on molecular docking, luteolin 7,3′-disulfate binding suggests blocking of the substrate access channel. However, an alternative site on the proximal surface where the redox partner binds cannot be excluded. Overall, flavonoids have the potential to inhibit the activity of human CYP51A1 and should be further explored for their cholesterol-lowering and anti-cancer activity.

scholarly journals Transformation of Construction Cement to a Self-Healing Hybrid Binder

2019 ◽  
Vol 20 (12) ◽  
pp. 2948 ◽  
Author(s):  
Werner E.G. Müller ◽  
Emad Tolba ◽  
Shunfeng Wang ◽  
Qiang Li ◽  
Meik Neufurth ◽  
...  
Keyword(s):  
Soil Bacteria ◽  
Construction Material ◽  
Water Soluble ◽  
The Self ◽  
Average Chain Length ◽  
Self Healing ◽  
Cement Concrete ◽  
Low Concentrations ◽  
Natural Mechanism ◽  
Long Chain

A new biomimetic strategy to im prove the self-healing properties of Portland cement is presented that is based on the application of the biogenic inorganic polymer polyphosphate (polyP), which is used as a cement admixture. The data show that synthetic linear polyp, with an average chain length of 40, as well as natural long-chain polyP isolated from soil bacteria, has the ability to support self-healing of this construction material. Furthermore, polyP, used as a water-soluble Na-salt, is subject to Na+/Ca2+ exchange by the Ca2+ from the cement, resulting in the formation of a water-rich coacervate when added to the cement surface, especially to the surface of bacteria-containing cement/concrete samples. The addition of polyP in low concentrations (<1% on weight basis for the solids) not only accelerated the hardening of cement/concrete but also the healing of microcracks present in the material. The results suggest that long-chain polyP is a promising additive that increases the self-healing capacity of cement by mimicking a bacteria-mediated natural mechanism.

Study of Red Halophilic Bacteria in Solar Salt and Salted Fish: II. Bacto-oxgall as a Selective Agent for Differentiation

1956 ◽  
Vol 13 (2) ◽  
pp. 195-199 ◽  
Author(s):  
H. P. Dussault
Keyword(s):  
Halophilic Bacteria ◽  
Partial Identification ◽  
Selective Medium ◽  
Selective Agent ◽  
Simple Method ◽  
Solar Salt ◽  
Salted Fish ◽  
Low Concentrations ◽  
Fish Samples

A simple method, based on oxgall tolerance, is proposed for differentiating red halophilic bacteria commonly found in solar salt and discoloured salted codfish. Tests carried out on 18 strains isolated from various sources have shown that the rod forms are inhibited by low concentrations of Bacto-oxgall and that the coccus forms tolerate relatively high ones. Bacto-oxgall can thus be used as the basis of a simple selective medium. This test has been found useful for the isolation, purification and partial identification of unidentified strains and also for determining the relative proportions of the two main types of red halophilic bacteria present in solar salt and salted fish samples.

scholarly journals Studies on silk proteins I. The properties and constitution of fibroin. The conversion of fibroin into a water-soluble form and its bearing on the phenomenon of denaturation

1947 ◽  
Vol 190 (1021) ◽  
pp. 145-169 ◽  
Keyword(s):  
Molecular Weight ◽  
Soluble Protein ◽  
Optical Rotation ◽  
Amino Nitrogen ◽  
Water Soluble ◽  
Soluble Form ◽  
Secondary Process ◽  
Amide Nitrogen ◽  
Water Soluble Protein ◽  
The Mean

Some of the constituent amino-acids of fibroin (degummed silk) are determined. Special attention is directed to histidine, owing to its use in the calculation of the molecular weight of fibroin. A value of 0⋅45% has been found by methods in which the histidine is isolated as nitranilate or di-(3:4-dichlorobenzenesulphonate). Other values obtained are serine 12⋅6%, threonine 1⋅5%, tyrosine 10⋅6%, and proline 1⋅5%. Hydroxyproline appears to be absent, but the presence of small amounts of some hydroxyamino-acid other than serine and threonine is indicated. The mean residue weight of fibroin is determined by three methods, one of which is a new method based on analysis of the complex formed between fibroin and cupri-ethylenediamine. This method gives a Cu:fibroin-N ratio of 1:1⋅92 and, if allowance is made for co-ordination with the tyrosine hydroxy1 group, an equivalence of 1⋅964 atoms of peptide-nitrogen to 1 atom of copper is obtained. The three methods give an average value of 78⋅0 for the mean residue weight of fibroin. This value, together with the most acceptable data for amino-acid constituents, indicate that the unidentified anhydro-residues (about 20%) have a mean residue weight of about 107. Evidence is presented that fibroin contains no amide-nitrogen. Methods for the determination of amide-nitrogen at present in use, which indicate a content of 1 to 2%, are considered to be unreliable. Fibroin dissolved in cupri-ethylenediamine gives, on neutralization and dialysis of the resulting solution, a water-soluble protein. The production of this water-soluble protein is attended by little or no degradation of the original fibroin as shown by determinations of fluidity, amino-nitrogen, and acid- and alkali-combining power. The water-soluble protein is precipitated by the normal protein-precipitating reagents, but in every instance examined the precipitated material exhibits an insolubility comparable with that of the original fibroin. Factors responsible for the solubilization process are investigated and data for molecular weight, titration values, ultra-violet absorption spectra, reducing activity, optical rotation, tryptic hydrolysis, and viscosity for both soluble and dispersed fibroin are given. Soluble fibroin has [ α ] D 15 — 53⋅1° and dispersed fibroin [ α ] D 15 — 58⋅9°, both in aqueous media. The preparation and properties of films and filaments of fibroin are described. Films of fibroin can be prepared that are water-soluble. On stretching, these films show strain-birefringence, acquire considerable tensile strength, and become insoluble in water, but X-ray examination gives the β -keratin pattern for both the stretched and unstretched films. Reasons are advanced for considering the water-soluble form of fibroin to be the native or renatured protein and the original protein to be the denatured form. The denaturation of fibroin is discussed on the basis that denaturation is essentially an unfolding of a coiled long-chain molecule. The subsequent aggregation of the uncoiled molecules to give an insoluble product is considered to be a secondary process. Some aspects of protein and polypeptide chains as macro-molecules are also discussed.

THE ABSORPTION OF VITAMIN A IN PREMATURELY BORN INFANTS

PEDIATRICS ◽  
1948 ◽  
Vol 1 (4) ◽  
pp. 505-511
Author(s):  
STEWART H. CLIFFORD ◽  
KATHLEEN FAHEY WELLER
Keyword(s):  
Vitamin A ◽  
Premature Infants ◽  
Test Dose ◽  
Water Soluble ◽  
Soluble Form ◽  
Oral Ingestion ◽  
Retrolental Fibroplasia ◽  
Practical Advantage ◽  
The Mean ◽  
Absorption Level

Forty-two premature infants were tested for vitamin A absorption after the oral ingestion of 0.5 cc. (35,000 U.S.P. units) of percomorph liver oil. Only three (7%) showed good absorption levels. The mean absorption level found from three to five hours after the test dose was 16 units of vitamin A. Forty-one were tested for vitamin A absorption after the oral ingestion of either 2 cc. or 3 cc. (16,000-24,000 U.S.P. units) of vitamin A in a vehicle of either alcohol or propylene glycol. Of these 37 (90%) showed good absorption levels. The mean absorption level found from three to five hours after the test dose was 85 units of vitamin A. Retrolental fibroplasia could not be prevented from developing in a certain number of premature infants' eyes by the daily oral administration of 5000 U.S.P. of vitamin A in an absorbable water soluble form. Even the addition of 20,000 U.S.P. units of vitamin A in oil by intramuscular injection failed to prevent the development of bilateral retrolental fibroplasia in one infant. If vitamin D follows the same laws of absorption as does vitamin A, the provision of both A and D in a readily absorbable form should be of great practical advantage to the prematurely born infant.

The effect of a benzodiazepine, flurazepam, on the response of in vitro skeletal muscle preparations to muscle relaxants: are purines or their receptors involved?

1982 ◽  
Vol 60 (7) ◽  
pp. 877-884 ◽  
Author(s):  
John T. Hamilton ◽  
Peggy A. Stone
Keyword(s):  
Skeletal Muscle ◽  
Phrenic Nerve ◽  
Neuromuscular Blocking ◽  
Muscle Relaxants ◽  
Water Soluble ◽  
Neuromuscular Activity ◽  
Changing Trends ◽  
Low Concentrations ◽  
Partial Blockade

Changing trends in the use of anxiolytic agents and recent reassessment of their neuropharmacological activity has prompted this evaluation of the peripheral neuromuscular activity of the benzodiazepine, flurazepam. In previous reports we have documented peripheral neuromuscular activity of chlordiazepoxide and diazepam on the rat phrenic nerve diaphragm preparation. The water soluble benzodiazepine, flurazepam, has been studied on the rat phrenic nerve diaphragm and frog rectus abdominis in vitro. On the former preparation flurazepam enhanced and then blocked the response to indirect electrical stimulation (0.2 Hz) and readily blocked posttetanic potentiation and prevented the preparation from sustaining a tetanic contracture (30 Hz). On the later preparation, flurazepam blocked in a noncompetitive manner the response of the frog muscle to applied cholinergic agonists. Studies on the rat preparation with the neuromuscular blocking drug succinylcholine have shown an unexpected protection against blockade in preparations pretreated with low concentrations of flurazepam. This was not observed when flurazepam was given prior to d-tubocurarinc. The application of adenosine to rat diaphragms during steady-state partial blockade caused by flurazepam or d-tubocurarine showed an inhibiting action of adenosine which was reversed by theophylline. Pretreatment of rat preparations with dipyridamole significantly enhanced the blocking action of standard concentrations of succinylcholine.These results, along with those in the literature, encourage a reassessment of the action of purines and benzodiazepines on skeletal muscle and encourage a consideration of a possible involvement of purinergic neuromodulation of transmission which is unmasked when the safety factor for transmission is altered by muscle relaxants. The possible clinical significance of protection against succinylcholine by benzodiazepines is noted.

scholarly journals Dietary Choline Intake: Current State of Knowledge Across the Life Cycle

Nutrients ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1513 ◽  
Author(s):  
Alejandra Wiedeman ◽  
Susan Barr ◽  
Timothy Green ◽  
Zhaoming Xu ◽  
Sheila Innis ◽  
...  
Keyword(s):  
Life Cycle ◽  
Current Knowledge ◽  
Water Soluble ◽  
Food Sources ◽  
Soluble Form ◽  
Dietary Recommendations ◽  
Current State ◽  
Dietary Nutrient ◽  
Choline Intake ◽  
Dietary Choline

Choline, an essential dietary nutrient for humans, is required for the synthesis of the neurotransmitter, acetylcholine, the methyl group donor, betaine, and phospholipids; and therefore, choline is involved in a broad range of critical physiological functions across all stages of the life cycle. The current dietary recommendations for choline have been established as Adequate Intakes (AIs) for total choline; however, dietary choline is present in multiple different forms that are both water-soluble (e.g., free choline, phosphocholine, and glycerophosphocholine) and lipid-soluble (e.g., phosphatidylcholine and sphingomyelin). Interestingly, the different dietary choline forms consumed during infancy differ from those in adulthood. This can be explained by the primary food source, where the majority of choline present in human milk is in the water-soluble form, versus lipid-soluble forms for foods consumed later on. This review summarizes the current knowledge on dietary recommendations and assessment methods, and dietary choline intake from food sources across the life cycle.

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