Roles of the Hydrophobic Tail Groups on the Properties of CO-Switchable Surfactants

2019 ◽  
Author(s):  
Qingfeng Hou ◽  
Qi Wu ◽  
Yan Xu ◽  
Xiaobo Zheng ◽  
Yujun Zhao ◽  
...  
Keyword(s):  
Switchable Surfactants ◽  
Hydrophobic Tail

scholarly journals Mutational Analysis of the Hydrophobic Tail of the Human Immunodeficiency Virus Type 1 p6Gag Protein Produces a Mutant That Fails To Package Its Envelope Protein

1999 ◽  
Vol 73 (1) ◽  
pp. 19-28 ◽  
Author(s):  
David E. Ott ◽  
Elena N. Chertova ◽  
Laura K. Busch ◽  
Lori V. Coren ◽  
Tracy D. Gagliardi ◽  
...  
Keyword(s):  
Amino Acids ◽  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Human Immunodeficiency Virus Type ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Hydrophobic Tail ◽  
Carboxyl Terminal ◽  
Hiv 1

ABSTRACT The p6Gag protein of human immunodeficiency virus type 1 (HIV-1) is produced as the carboxyl-terminal sequence within the Gag polyprotein. The amino acid composition of this protein is high in hydrophilic and polar residues except for a patch of relatively hydrophobic amino acids found in the carboxyl-terminal 16 amino acids. Internal cleavage of p6Gag between Y36 and P37, apparently by the HIV-1 protease, removes this hydrophobic tail region from approximately 30% of the mature p6Gag proteins in HIV-1MN. To investigate the importance of this cleavage and the hydrophobic nature of this portion of p6Gag, site-directed mutations were made at the minor protease cleavage site and within the hydrophobic tail. The results showed that all of the single-amino-acid-replacement mutants exhibited either reduced or undetectable cleavage at the site yet almost all were nearly as infectious as wild-type virus, demonstrating that processing at this site is not important for viral replication. However, one exception, Y36F, was 300-fold as infectious the wild type. In contrast to the single-substitution mutants, a virus with two substitutions in this region of p6Gag, Y36S-L41P, could not infect susceptible cells. Protein analysis showed that while the processing of the Gag precursor was normal, the double mutant did not incorporate Env into virus particles. This mutant could be complemented with surface glycoproteins from vesicular stomatitis virus and murine leukemia virus, showing that the inability to incorporate Env was the lethal defect for the Y36S-L41P virus. However, this mutant was not rescued by an HIV-1 Env with a truncated gp41TM cytoplasmic domain, showing that it is phenotypically different from the previously described MA mutants that do not incorporate their full-length Env proteins. Cotransfection experiments with Y36S-L41P and wild-type proviral DNAs revealed that the mutant Gag dominantly blocked the incorporation of Env by wild-type Gag. These results show that the Y36S-L41P p6Gag mutation dramatically blocks the incorporation of HIV-1 Env, presumably acting late in assembly and early during budding.

Synthesis of hierarchical MFI zeolites with a micro–macroporous core@mesoporous shell structure

2019 ◽  
Vol 55 (6) ◽  
pp. 810-813
Author(s):  
Yunjuan Zhang ◽  
Xinbao Han ◽  
Shunai Che
Keyword(s):  
Shell Structure ◽  
Core Shell ◽  
Hydrophobic Tail ◽  
Mesoporous Shell ◽  
Mfi Zeolites

Core–shell structured ZSM-5 zeolites were synthesized by using a bifunctional surfactant containing alkene group in the hydrophobic tail.

scholarly journals Antioxidant Properties of Embelin in Cell Culture. Electrochemistry and Theoretical Mechanism of Scavenging. Potential Scavenging of Superoxide Radical through the Cell Membrane

Antioxidants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 382 ◽  
Author(s):  
Francesco Caruso ◽  
Miriam Rossi ◽  
Sarjit Kaur ◽  
Emmanuel Garcia-Villar ◽  
Nora Molasky ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Superoxide Radical ◽  
Antioxidant Properties ◽  
Chemical Species ◽  
Antioxidant Defense System ◽  
Butylated Hydroxytoluene ◽  
Embelia Ribes ◽  
Diphenyltetrazolium Bromide ◽  
Hydrophobic Tail ◽  
Theoretical Mechanism

Embelin, a plant natural product found in Lysimachia punctata (Primulaceae), and Embelia ribes Burm (Myrsinaceae) fruit, possesses interesting biological and pharmacological properties. It is a unique chemical species as it includes both quinone and hydroquinone functional groups plus a long hydrophobic tail. By using hydrodynamic voltammetry, which generates the superoxide radical in situ, we show an unusual scavenging capability by embelin. Embelin as a scavenger of superoxide is stronger than the common food additive antioxidant 2,6-bis(1,1-dimethylethyl)-4-20 methylphenol, (butylated hydroxytoluene, BHT). In fact, embelin is even able to completely abolish the superoxide radical in the voltaic cell. Computational results indicate that two different types of embelin scavenging actions may be involved, initially through π–π interaction and followed by proton capture in the cell. A related mechanism describes embelin’s ability to circumvent superoxide leaking by transforming the anion radical into molecular oxygen. In order to confirm its antioxidant properties, its biological activity was tested in a study carried out in THP-1 human leukemic monocytes and BV-2 mice microglia. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, proliferation curves and antioxidant activity by the use of a fluorescent probe showed good antioxidant properties at 24 h. This suggests that embelin’s long alkyl C10 tail may be useful for cell membrane insertion which stimulates the antioxidant defense system, and cytoprotection in microglia. In conclusion, embelin could be an interesting pharmacological tool able to decrease the damage associated with metabolic and neurodegenerative diseases.

CO Foam Stabilized with Switchable Surfactants and Modified Nanoparticles Effected by PH and Salinity

2020 ◽  
Author(s):  
Xuan Zhang ◽  
Guicai Zhang ◽  
Jijiang Ge ◽  
Yanqing Wang
Keyword(s):  
Switchable Surfactants

scholarly journals Surface active fatty acid ILs: Influence of the hydrophobic tail and/or the imidazolium hydroxyl functionalization on aggregates formation

2019 ◽  
Vol 289 ◽  
pp. 111155 ◽  
Author(s):  
Andrea Mezzetta ◽  
Justyna Łuczak ◽  
Julia Woch ◽  
Cinzia Chiappe ◽  
Janusz Nowicki ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Hydrophobic Tail ◽  
Surface Active

Vesicle transition of catanionic redox-switchable surfactants controlled by DNA with different chain lengths

2019 ◽  
Vol 549 ◽  
pp. 89-97 ◽  
Author(s):  
Huizhong Liu ◽  
Ling Wang ◽  
Xiaolin Wang ◽  
Yuanyuan Hu ◽  
Lei Feng ◽  
...  
Keyword(s):  
Switchable Surfactants ◽  
Chain Lengths

scholarly journals The protein bcl-2 alpha does not require membrane attachment, but two conserved domains to suppress apoptosis.

1994 ◽  
Vol 126 (4) ◽  
pp. 1059-1068 ◽  
Author(s):  
C Borner ◽  
I Martinou ◽  
C Mattmann ◽  
M Irmler ◽  
E Schaerer ◽  
...  
Keyword(s):  
Sympathetic Neurons ◽  
Point Mutations ◽  
Cell Types ◽  
In Vitro Transcription ◽  
Site Directed Mutagenesis ◽  
Full Activity ◽  
Membrane Attachment ◽  
Hydrophobic Tail ◽  
Critical Regions

Bcl-2 is a mitochondrial- and perinuclear-associated protein that prolongs the lifespan of a variety of cell types by interfering with programmed cell death (apoptosis). Bcl-2 seems to function in an antioxidant pathway, and it is believed that membrane attachment mediated by a COOH-terminal hydrophobic tail is required for its full activity. To identify critical regions in bcl-2 alpha for subcellular localization, activity, and/or interaction with other proteins, we created, by site-directed mutagenesis, various deletion, truncation, and point mutations. We show here that membrane attachment is not required for the survival activity of bcl-2 alpha. A truncation mutant of bcl-2 alpha lacking the last 33 amino acids (T3.1) including the hydrophobic COOH terminus shows full activity in blocking apoptosis of nerve growth factor-deprived sympathetic neurons or TNF-alpha-treated L929 fibroblasts. Confocal microscopy reveals that the T3 mutant departs into the extremities of neurites in neurons and filopodias in fibroblasts. Consistently, T3 is predominantly detected in the soluble fraction by Western blotting, and is not inserted into microsomes after in vitro transcription/translation. We further provide evidence for motifs (S-N and S-II) at the NH2 and COOH terminus of bcl-2, which are crucial for its activity.

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