scholarly journals Chemical properties of the functional groups of insulin

1981 ◽  
Vol 193 (2) ◽  
pp. 419-425 ◽  
Author(s):  
Y K Chan ◽  
G Oda ◽  
H Kaplan
Keyword(s):  
Functional Groups ◽  
Chemical Properties ◽  
Amino Group ◽  
Histidine Residues ◽  
Tyrosine Residues ◽  
Order Of Magnitude ◽  
Phenolic Group ◽  
Dimeric Form ◽  
A Chain ◽  
Phenylalanine Residue

The method of competitive binding [Kaplan, Stevenson & Hartley (1971) Biochem. J. 124, 289-299] with 1-fluoro-2,4-dinitrobenzene as the labelling reagent [Duggleby & Kaplan (1975) Biochemistry 14, 5168-5175] was used to determine the chemical properties, namely pK and reactivity, of the amino groups, the histidine residues and the tyrosine residues of the dimeric form of pig zinc-free insulin at 20.0 degrees C. The N-terminal glycine residue of the A-chain has a pK of 7.7 and a slightly higher than normal reactivity. The N-terminal phenylalanine residue of the B-chain has a pK of 6.9 and is approximately an order of magnitude more reactive than a corresponding amino group with the same pK value. The lysine epsilon-amino group has an unusually low pK of 7.0 but has approximately the expected reactivity of such a group. In the case of the two histidine and four tyrosine residues only the average properties of each class were determined. The histidine residues have a pK value of approx. 6.6, but, however, their reactivity is at least an order of magnitude greater than that of a free imidazole group. The tyrosine residues have a pK value of approx. 10, but their average reactivities are substantially less than for a free phenolic group. At alkaline pH values above 8 the reactivity of all the functional groups show sharp discontinuities, indicating that insulin is undergoing a structural change that alters the properties of these groups.

scholarly journals The Process of Stellar Tidal Disruption by Supermassive Black Holes

2021 ◽  
Vol 217 (3) ◽  
Author(s):  
E. M. Rossi ◽  
N. C. Stone ◽  
J. A. P. Law-Smith ◽  
M. Macleod ◽  
G. Lodato ◽  
...  
Keyword(s):  
Black Holes ◽  
Initial Conditions ◽  
Numerical Models ◽  
Binary Star ◽  
Tidal Disruption ◽  
Massive Black Hole ◽  
Accretion Flows ◽  
Simple Order ◽  
Order Of Magnitude ◽  
A Chain

AbstractTidal disruption events (TDEs) are among the brightest transients in the optical, ultraviolet, and X-ray sky. These flares are set into motion when a star is torn apart by the tidal field of a massive black hole, triggering a chain of events which is – so far – incompletely understood. However, the disruption process has been studied extensively for almost half a century, and unlike the later stages of a TDE, our understanding of the disruption itself is reasonably well converged. In this Chapter, we review both analytical and numerical models for stellar tidal disruption. Starting with relatively simple, order-of-magnitude physics, we review models of increasing sophistication, the semi-analytic “affine formalism,” hydrodynamic simulations of the disruption of polytropic stars, and the most recent hydrodynamic results concerning the disruption of realistic stellar models. Our review surveys the immediate aftermath of disruption in both typical and more unusual TDEs, exploring how the fate of the tidal debris changes if one considers non-main sequence stars, deeply penetrating tidal encounters, binary star systems, and sub-parabolic orbits. The stellar tidal disruption process provides the initial conditions needed to model the formation of accretion flows around quiescent massive black holes, and in some cases may also lead to directly observable emission, for example via shock breakout, gravitational waves or runaway nuclear fusion in deeply plunging TDEs.

Migration of protons in a chain of tyrosine residues

2001 ◽  
Vol 84 (4) ◽  
pp. 409-415 ◽  
Author(s):  
V. E. Stefanov ◽  
A. A. Tulub
Keyword(s):  
Tyrosine Residues ◽  
A Chain

Vegetable oils – raw materials for producing biodiesel

2021 ◽  
Vol 80 (2) ◽  
pp. 286-292
Author(s):  
T. Mamilov ◽  
◽  
G.S. Aitkaliyeva ◽  
A.B. Ismailova ◽  
M.A. Yelubay ◽  
...  
Keyword(s):  
Functional Groups ◽  
Vegetable Oils ◽  
Raw Materials ◽  
Chemical Properties ◽  
Biodiesel Fuel ◽  
Physical And Chemical Properties ◽  
Sunflower Oils ◽  
Transesterification Method ◽  
Physical And Chemical ◽  
And Chemical Properties

This paper presents the results of a study of the physical and chemical properties of samples of vegetable oils (sunflower, rapeseed, olive). It has been shown that the viscosity of oils varies from 41.4 to 61.7 cSt at a temperature of 40 ° C for olive and sunflower oils, respectively. The acid numbers of the oil samples were also determined, it was found that the lowest indicator is characteristic of sunflower oil. Pour points of oils also range from -3 to -16 ° C for olive and sunflower oils, respectively. Using the method of IR spectroscopy, functional groups in the composition of samples of vegetable oils were studied and it was shown that the composition of oils contains carbonyl and hydroxyl functional groups, indicating the presence of carboxylic acids. Based on studies of the physical and chemical properties of vegetable oils, it was found that sunflower, olive and rapeseed oils can serve as raw materials for the synthesis of biofuels based on them, since they contain free fatty acids. To obtain biodiesel fuel based on vegetable oils, it is planned to use the transesterification method in the presence of various catalysts (alkaline, acidic, and complex).

Quantitative Measurement of Functional Groups on Nanocarbon Allotropes Surface by Boehm Titration

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
M. Hernández-Ortiz ◽  
J. D. Lozano-López ◽  
S. M. Durón ◽  
M. Galván-Valencia ◽  
Y. Estevez-Martínez ◽  
...  
Keyword(s):  
Functional Groups ◽  
Concentration Ratio ◽  
Quantitative Measurement ◽  
Carboxyl Group ◽  
Multiwalled Carbon ◽  
Derivative Method ◽  
Order Of Magnitude ◽  
Treated Carbon ◽  
Second Derivative Method ◽  
Vulcan Carbon

Various nanocarbons (NCs) were used to study their surface groups under standardized Bohem titration, including: multiwalled carbon nanotube (CNT), graphene (G), Vulcan carbon (VC), and nanodiamond (ND). Endpoint-measured titration using second derivative method to quantify carboxylic, lactonic, and phenolic groups created on treated carbon surfaces shows a high precision comparable to other recent reports and with errors of 1 order of magnitude lower. The results exhibit major concentration of carboxyl group increased after the NCs were oxidized compared to the amount of other functional groups like phenols and lactonic groups. It is important highlight, the concentration ratio of carboxyl group with VC:VC-O was showed at 1:77, exhibited a major result regarding other NCs which exhibited ratios of 1:4.5, 1:1.4, and 1:2.5 for ND:ND-O, CNT:CNT-O, and G:G-O, respectively. It is concluded that VC is a NC that competes and excels in its capacity of oxidation with respect to the popular NCs as CNT, graphene (G), and ND.

Branched polystyrenes from suspension “Strathclyde” polymerization using a vulcanization accelerator as a chain transfer agent

2019 ◽  
Vol 10 (7) ◽  
pp. 885-890 ◽  
Author(s):  
Haiyang Yong ◽  
Yongpeng Miao ◽  
Sigen A ◽  
Dong Quan ◽  
Alojz Ivankovic ◽  
...  
Keyword(s):  
Chain Transfer ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Branched Polymers ◽  
Chain Transfer Agent ◽  
Molecular Architecture ◽  
Physical Chemical ◽  
A Chain ◽  
Vulcanization Accelerator

Branched polymers exhibit a unique three-dimensional (3D) molecular architecture and distinctive physical/chemical properties, and thus have been applied in a wide variety of fields.

scholarly journals Variation in Feedstock Wood Chemistry Strongly Influences Biochar Liming Potential

Soil Systems ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 26 ◽  
Author(s):  
Sossina Gezahegn ◽  
Mohini Sain ◽  
Sean Thomas
Keyword(s):  
Functional Group ◽  
Pyrolysis Temperature ◽  
Chemical Properties ◽  
Base Cation ◽  
Surface Functional Group ◽  
Wood Chemistry ◽  
Incubation Experiments ◽  
Phenolic Group ◽  
Capacity Data ◽  
Group Concentration

Chars intended for use as soil amendment (“biochars”) vary greatly in their chemical and physical properties. In the present study, 19 Canadian temperate wood feedstocks were charred across a range of pyrolysis temperatures from 300–700 °C. The resulting 95 biochars were tested for their physio-chemical properties and liming capacity. Data indicated increasing base cation concentrations including Ca, Mg, and K (elements that characteristically form liming compounds, i.e., carbonates) as pyrolysis temperature increased. Acidic surface functional groups were analyzed with modified Boehm titration: Carboxylic and lactonic functional group concentrations decreased and phenolic group concentration increased with pyrolysis temperature. Functional group composition also varied greatly with feedstock: In particular, conifer-derived biochars produced at pyrolysis temperatures <500 °C showed much higher carboxylic and lactonic functional group concentrations than did angiosperm-derived biochars. Liming capacity was assessed using soil incubation experiments and was positively related to biochar pH. Both acidic surface functional group concentration and nutrient element concentration influenced biochar pH: we developed a non-linear functional relationship that predicts biochar pH from the ratio of carboxylic to phenolic moieties, and concentrations of Ca and K. Biochar’s liming components that are inherited from feedstock and predictably modified by pyrolysis temperature provide a basis for optimizing the production of biochar with desired pH and liming characteristics.

Spatially Organized Response Zones in Rat Olfactory Epithelium

1997 ◽  
Vol 77 (4) ◽  
pp. 1950-1962 ◽  
Author(s):  
John W. Scott ◽  
Donna E. Shannon ◽  
Jeff Charpentier ◽  
Lisa M. Davis ◽  
Craig Kaplan
Keyword(s):  
Gene Expression ◽  
Functional Groups ◽  
Olfactory Epithelium ◽  
Olfactory Receptor ◽  
Receptor Gene ◽  
Chemical Properties ◽  
Receptor Expression ◽  
Response Distribution ◽  
Chemical Structures ◽  
Four Electrodes

Scott, John W., Donna E. Shannon, Jeff Charpentier, Lisa M. Davis, and Craig Kaplan. Spatially organized response zones in rat olfactory epithelium. J. Neurophysiol. 77: 1950–1962, 1997. Electroolfactogram recordings were made with a four-electrode assembly from the olfactory epithelium overlying the endoturbinate bones facing the nasal septum. In this study we tested whether odors of different chemical structures produce maximal responses along longitudinally oriented regions following the olfactory receptor gene expression zones described in the literature. The distribution of responses along the dorsal-to-ventral direction of this epithelium (i.e., across the expression zones) was tested in two types of experiments. In one, four electrodes were fixed along the dorsal-to-ventral axis of one turbinate bone. In the other, four electrodes were placed in corresponding positions on four turbinate bones and moved together up toward the top of the bone. These experiments compared the odorants limonene and α-terpinene, which are simple hydrocarbons, with carvone and menthone, which differ from the hydrocarbons by the presence of ketone groups. All responses were standardized to an amyl acetate or ethyl butyrate standard. The responses to limonene and α-terpinene were often larger for the ventral electrodes. The responses to carvone and menthone were largest for the dorsal electrodes. Intermediate electrodes gave responses that were intermediate in amplitude for these odors. The possibility that direction of air flow caused the observed response distributions was directly tested in experiments with odor nozzles placed in two positions. The relatively larger dorsal responses to carvone and relatively larger ventral responses to limonene were present despite odor nozzle position. We conclude that the responses to this set of odors vary systematically in a fashion parallel to the four gene expression zones. The odorant property that governs this response distribution may be related to the presence of oxygen-containing functional groups. Certain odors evoked larger responses at the intermediate electrode sites than at other sites. Cineole was the best example of this effect. This observation shows that not all oxygen-containing functional groups produce the same effect. Although we cannot exclude other possible mechanisms, these three response gradients may be produced by the four receptor expression zones described for many of the putative olfactory receptor genes. Therefore many of the receptors in each zone may share common properties. It remains to be determined whether this zonal input is significant in central odor processing. However, the correlation of odor chemical properties with the structure of receptor molecules in each zone may provide significant leads to structure-function relationships in vertebrate olfaction.

scholarly journals Mechanism of HCB-Modified Asphalt and Dynamic Properties of Mixtures

2020 ◽  
Vol 10 (14) ◽  
pp. 4971
Author(s):  
Zhan Ding ◽  
Jinfei Su ◽  
Peilong Li ◽  
Hui Bing
Keyword(s):  
Functional Groups ◽  
Oxygen Content ◽  
Performance Test ◽  
Dynamic Properties ◽  
Chemical Properties ◽  
Active Surface ◽  
Asphalt Mixtures ◽  
Low Frequencies ◽  
High Oxygen Content ◽  
Modified Asphalt

Hydroxymethyl carbon black (HCB) was prepared as an asphalt modifier with a high oxygen content and active surface chemical properties. The microstructure of HCB was analyzed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. The improvement effect of HCB on asphalt’s physical, dynamic shear, rheological, and aging properties was evaluated. To analyze the dynamic properties of the HCB-modified asphalt mixtures, a simple performance test (SPT) was conducted, and then the change laws of the dynamic modulus and phase angle for the HCB mixtures were clarified. The results showed that the surface of HCB is smooth and that the oxygen content increases with the generation of hydroxyl functional groups. Polar oxygen-containing functional groups and hydrogen bonds are helpful in improving the resistance to cracking and aging. The surface activity of HCB is susceptible to temperature and frequency, causing a slight influence of HCB on the viscoelasticity of asphalt mixtures at high and low frequencies. At low temperatures and high frequencies, the HCB enhanced the elasticity characteristics and weakened the viscosity characteristics of asphalt mixtures.

Relation of chemical structure to spatial distribution of sensory responses in rat olfactory epithelium

1996 ◽  
Vol 75 (5) ◽  
pp. 2036-2049 ◽  
Author(s):  
J. W. Scott ◽  
L. M. Davis ◽  
D. Shannon ◽  
C. Kaplan
Keyword(s):  
Functional Groups ◽  
Olfactory Epithelium ◽  
Chemical Properties ◽  
Major Exception ◽  
Cyclic Alkanes ◽  
Lateral Space ◽  
Far Lateral ◽  
Sensory Responses ◽  
Level Of Analysis ◽  
Made In

1. Electroolfactogram (EOG) recordings were made in three configurations from the rat olfactory epithelium. Each configuration compared recordings in the dorsomedial recess of the epithelium with recordings in ventral or lateral parts of the epithelium. Most comparisons were made with simultaneous recordings. The exception was a series in which the dorsal recess and lateral space between the base of two turbinate bones were directly exposed for odor application and recording. The spatial distributions of maximal responses were largely independent of recording configuration. 2. Simultaneous recordings compared dorsomedial and lateral sites in the epithelium during stimulation with a series of 50 odorants. The odorants that evoked larger responses in the lateral sites were usually compounds that lacked oxygen containing functional groups (such as the carbonyl group). This was true for straight chain and cyclic alkanes, for terpine compounds, and for aromatic compounds. The major exception was cineole, a bicyclic compound. All compounds containing ketone groups evoked larger dorsomedial responses. The responses of aldehydes and esters depended upon whether they were attached to aliphatic or aromatic chains. 3. In the three types of preparation, the sites responding best to ketones were in the same expression zone of the epithelium according to published maps for the rat and mouse. The sites responding best to odors without functional groups were in the far lateral or ventral region and corresponded to one of the two most lateral and ventral expression zones. This fact suggests that the receptors in these regions have a preference for particular chemical properties. This level of analysis cannot determine whether all receptors in each zone have a stronger response to certain properties of these odorants or whether each zone contains different proportions of receptors with these properties.

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