Free Amino Group-Directed γ-C(sp3)–H Arylation of α-Amino Esters with Diaryliodonium Triflates by Palladium Catalysis

2019 ◽  
Vol 84 (9) ◽  
pp. 5684-5694 ◽  
Author(s):  
Pranab K. Pramanick ◽  
Zhibing Zhou ◽  
Zhen-Lin Hou ◽  
Bo Yao
Keyword(s):  
Free Amino ◽  
Palladium Catalysis ◽  
Amino Group ◽  
Amino Esters

Ruthenium-Catalyzed Regioselective C–H Alkenylation Directed by a Free Amino Group

2013 ◽  
Vol 15 (15) ◽  
pp. 3990-3993 ◽  
Author(s):  
Chiharu Suzuki ◽  
Koji Hirano ◽  
Tetsuya Satoh ◽  
Masahiro Miura
Keyword(s):  
Free Amino ◽  
Amino Group

Structure of the O-polysaccharide of Idiomarina zobellii KMM 231T containing two unusual amino sugars with the free amino group, 4-amino-4,6-dideoxy-d-glucose and 2-amino-2-deoxy-l-guluronic acid

2004 ◽  
Vol 339 (3) ◽  
pp. 477-482 ◽  
Author(s):  
Michelle Kilcoyne ◽  
Andrei V. Perepelov ◽  
Svetlana V. Tomshich ◽  
Nadezhda A. Komandrova ◽  
Alexander S. Shashkov ◽  
...  
Keyword(s):  
Free Amino ◽  
Amino Sugars ◽  
Amino Group ◽  
Group 4 ◽  
Guluronic Acid

Effect of cross-linking agents on insulin associated responses in adipocytes

1982 ◽  
Vol 60 (10) ◽  
pp. 987-1000 ◽  
Author(s):  
H. Joseph Goren ◽  
C. Ronald Kahn
Keyword(s):  
Insulin Receptor ◽  
Glucose Transport ◽  
Free Amino ◽  
Glucose Oxidation ◽  
Insulin Binding ◽  
Cross Linking ◽  
Amino Group ◽  
Amino Groups ◽  
Disuccinimidyl Suberate ◽  
Reactive Groups

The effect of 10 bifunctional cross-linking agents and four monofunctional analogues was studied on isolated adipocytes. [125I]Insulin binding and degradation, basal and insulin-stimulated glucose oxidation, and 3-O-methyl glucose uptake were measured. Two cross-linkers, which possess succinimide ester residues (disuccinimidyl suberate and dithiobis(succinimidyl propionate)) and react selectively with amino groups, appeared to react relatively specifically with the insulin receptor. Both produced a slight stimulation of basal glucose transport and metabolism, a marked inhibition of insulin-stimulated glucose transport and metabolism, and a marked decrease in insulin binding. Pretreatment of cells with unlabelled insulin partially blocked the effect of disuccinimidyl suberate, and as has been previously shown, disuccinimidyl suberate cross-linked insulin to its receptor. A monofunctional analogue of these compounds was 100-fold less active in altering cellular metabolic activity. Bisimidates, such as dimethyl suberimidate, dimethyl adipimidate, and dimethyl dithiobispropionimidate, also react with free amino groups but are more hydrophilic. These agents produced similar effects on glucose oxidation as the succinimide esters, but had little or no effect on insulin binding. The effects of these agents are not blocked by insulin and they do not cross-link insulin to its receptor. Mixed bifunctional reagents containing either a succinimide ester or an imidate and a group which reacts with thiols produced effects similar to the cross-linkers containing two succinimide groups or bisimidates, respectively. The bifunctional arylating agents difluorodinitrobenzene and bis(fluoronitrophenyl)sulfone produce marked effects on insulin binding and glucose oxidation at micromolar concentrations, but the monofunctional analogue fluorodinitrobenzene is almost equally active suggesting that with these compounds chemical modifications and not cross-linking was important. With neither the mixed bifunctional reagents, nor the arylating agents, did insulin pretreatment alter the effect of cross-linker and none of these agents cross-linked [125I]insulin to its receptor. These data suggest that the insulin receptor possesses a free amino group in a hydrophobic environment in its active site. A reactive amino group in a hydrophilic environment as well as other reactive groups are also present in some component of the insulin receptor–effector complex. Chemical modification or cross-linking of these functional groups results in an inhibition or mimicking of insulin action. Further study will be required to identify the exact locus of these sites.

scholarly journals Applications of Chitin and Chitosan in Industry and Medical Science: A Review

2016 ◽  
Vol 16 (1) ◽  
pp. 99-104 ◽  
Author(s):  
Shanta Pokhrel ◽  
Paras Nath Yadav ◽  
Rameshwar Adhikari
Keyword(s):  
Cell Wall ◽  
Free Amino ◽  
Science And Technology ◽  
Medical Science ◽  
Amino Group ◽  
Chitin And Chitosan

Chitin can be extracted from the exoskeletons of crustaceans, insects and mollusks and the cell wall of microorganisms. It can be converted into chitosan by deacetylation process. Chitosan shows more versatility than chitin due to its solubility and reactive free amino group (-NH2). This article helps to understand the importance and characteristics of chitin and chitosan by their various aspects such as properties and medical and industrial applications.Nepal Journal of Science and Technology Vol. 16, No.1 (2015) pp. 99-104

scholarly journals The free amino group of gramicidin S

1946 ◽  
Vol 40 (2) ◽  
pp. 261-262 ◽  
Author(s):  
F. Sanger
Keyword(s):  
Free Amino ◽  
Amino Group ◽  
Gramicidin S

scholarly journals Application of Asian pumpkin (Cucurbita ficifolia) serine proteinase for production of biologically active peptides from casein.

2013 ◽  
Vol 60 (1) ◽  
Author(s):  
Anna Dąbrowska ◽  
Marek Szołtysik ◽  
Konrad Babij ◽  
Marta Pokora ◽  
Aleksandra Zambrowicz ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Free Amino ◽  
Serine Proteinase ◽  
Biologically Active ◽  
Amino Group ◽  
Active Peptides ◽  
Rp Hplc ◽  
Amino Group Content ◽  
Biologically Active Peptides ◽  
Peptide Profiles

The main objective of this study was to determine potential application of a serine proteinase derived from Asian pumpkin for obtaining biologically active peptides from casein. The course of casein hydrolysis by three doses of the enzyme (50, 150, 300 U/mg of protein) was monitored for 24 hours by the determinations of: hydrolysis degree DH (%), free amino group content (μmole Gly/g), RP HPLC peptide profiles and by polyacrylamide gel electrophoresis. In all hydrolyzates analyzed antioxidant activities were determined using three tests: the ability to reduce iron ions in FRAP test, the ability to scavenge free radicals in DPPH test, and Fe(2+) chelating activity. The antimicrobial activity of obtained peptide fractions was determined as the ability to inhibit the growth of Escherichia coli, Bacillus cereus and Pseudomonas fluorescens in a diffusion plate test. The deepest degradation, expressed as the DH [%] and the free amino group content (67% and 7528 µmole Gly/mg, respectively), was noted in samples hydrolyzed with 300 U/ml of enzyme for 24 hours, while in other samples the determined values were about three and two times lower. The results were in agreement with the peptide profiles obtained by RP HPLC. The highest antioxidative activities determined in all tests were seen for the casein hydrolysate obtained with 300 U/mg protein of serine proteinase after 24 h of reaction (2.15 µM Trolox/mg, 96.15 µg Fe(3+)/mg, 814.97 µg Fe(2+)/mg). Antimicrobial activity was presented in three preparations. In other samples no antimicrobial activity was detected.

Lyso-Sulfatide Binds Factor Xa and Potently Inhibits Thrombin Generation.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1130-1130
Author(s):  
Subramanian Yegneswaran ◽  
Yajnavalka Banerjee ◽  
Jose A. Fernandez ◽  
Hiroshi Deguchi ◽  
John H. Griffin
Keyword(s):  
Free Amino ◽  
Conflicts Of Interest ◽  
Factor Xa ◽  
Coagulation System ◽  
Amino Group ◽  
Thrombin Time ◽  
Binding Studies ◽  
Binding Interaction ◽  
Dependent Inhibition ◽  
Gla Domain

Abstract Abstract 1130 Although phospholipids are well-recognized for their effects on coagulation reactions, little is generally known about the effects of sphingolipids on clotting pathways. Negatively-charged sulfatides can potently initiate the intrinsic pathway of coagulation system by binding and autoactivating factor (f) XII. Sphingosine potently inhibits the ability of factor Xa (fXa) to generate thrombin (fIIa) in the prothrombinase complex (II-ase) (fXa/fVa/phospholipids) by interacting directly with fXa's Gla domain. Here we report that lyso-sulfatide (lyso-SF) (sulfogalactosyl sphingosine), a lipid of minor abundance in plasma that is primarily in HDL particles, exhibits potent anticoagulant activity. Lyso-SF dose-dependently prolonged clotting in fXa-1-stage but not thrombin-time clotting assays. Lyso-SF inhibited II-ase activity by > 90 % in purified reaction mixtures (fXa/fVa/II) in the presence of 6 or 30 μM phospholipids (PL). However, lyso-SF did not inhibit fIIa generation by fXa/fVa in the absence of PL, suggesting the absolute requirement of PL for lyso-SF-dependent inhibition of fIIa generation. Lyso-SF inhibited fIIa generation by fXa/PL in the absence of fVa. Additionally, lyso-SF inhibited fIIa generation by Gla-domainless (gd)-fXa in the presence but not in the absence of fVa and PL. Lyso-SF-dependent inhibition of fIIa generation was also observed for fXa/fVa/PL when gd-II was used as the substrate instead of II. However, no inhibition by lyso-SF was observed when using gd-fXa/PL and gd-II/PL in the presence or absence of fVa. Lyso-SF had no effect on fXa or fIIa amidolytic activity. These data plus other studies suggested that ≥ two components of the II-ase complex needed to be PL-bound for potent inhibition of fIIa generation by lyso-SF. PL surfaces bind and assemble each the II-ase protein components; however, PL's and lyso-SF may also alter the conformations of fXa, fVa and II. To gain mechanistic insights for lyso-SF inhibition of II-ase activity, Surface Plasmon Resonance (SPR) and fluorescence spectroscopy were used to define molecular interactions. Remarkably, SPR binding studies showed that lyso-SF binds to immobilized fXa (KD = 83 μM) and gd-fXa (KD = 36 μM). Controls using SPR showed no binding of lyso-SF to immobilized fVIIa or fIXa whereas SPR confirmed the ability of fXa, fVIIa and fIXa to bind PL's. Fluorescence binding assays confirmed SPR data showing that lyso-SF bound to and altered the dansyl fluorescence of dansyl-GluGlyArg-labeled fXa (DEGR-fXa) both in the presence (KD = 50 μM) and absence (KD = 75 μM) of PL and that this binding required calcium ions. Thus, lyso-SF binds fXa outside the Gla domain. Fluorescence monitoring of fVa binding to DEGR-fXa in the presence of PL showed that lyso-SF inhibited this binding interaction. To characterize structure-activity relationships for lyso-SF inhibition of II-ase, different analogs of lyso-SF were tested for their ability to inhibit fIIa generation by gd-fXa/fVa/PL. Psychosine (galactosyl sphingosine), glucosyl sphingosine and lyso-sphingomyelin each inhibited fIIa generation showing that the sulfate ester moiety and the sugar group in lyso-SF were not essential for the anticoagulant effects of lyso-SF. However, acetylation of the free amino group in lyso-SF ablated its inhibition of fIIa generation showing that the free amino group on carbon 2 is essential for the inhibitory activity of lyso-SF. In conclusion, these findings show that lyso-SF and several of its analogs are potent anticoagulant lipids and that the mechanism for inhibition of fXa by lyso-SF may involve its binding to fXa at sites outside fXa's Gla domain. This suggests that certain sphingolipids may exert allosteric downregulation of fXa activity without inhibiting the enzyme's active site or the binding of the Gla domain to PL surfaces. Disclosures: No relevant conflicts of interest to declare.

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