Detection of salinomycin and lasalocid in chicken liver by icELISA based on functional bispecific single-chain antibody (scDb) and interpretation of molecular recognition mechanism

Background:Regenerating islet-derived gene family member 4 (Reg4), a well-investigated growth factor in the regenerative pancreas, has recently been reported to be highly associated with a majority of gastrointestinal cancers. Pathological hyper-expression or artificial over-expression of Reg4 causes acceleration of tumor growth, migration, and resistance to chemotherapeutic 5-Fluorouracil (5-FU). Until now, no method has been successfully established for eliminating the effects of Reg4 protein.Methods:This study reports the production of an engineered immunoglobin, a single-chain variable fragment (scFv-Reg4), to specifically bind Reg4 and block the bioactivity. The complementary-determining regions (CDRs) against Reg4 were assigned using MOE and ZDOCK servers. The binding affinity (KD) was determined by bio-layer interferometry (BLI). MKN45 and AGS cell proliferation was determined by Thiazolyl blue tetrazolium bromide (MTT) method and the cell apoptosis was detected by flow cytometry assay.Results:The KD of scFv-Reg4 to Reg4 was determined to be 1.91×10-8. In MKN45 and AGS cell lines, scFv- Reg4 depressed Reg4-stimulated cell proliferation and the inhibitory rates were 27.7±1.5% and 17.3±2.6%, respectively. Furthermore, scFv significantly enhanced 5-FU-induced cell death, from 23.0±1.0% to 28.4±1.2% in MKN45 and 28.2±0.7% to 36.6±0.6% in AGS cells. Treatment with scFv alone could lyse cancer cells to a certain extent, but no significance has been observed.Conclusion:The single-chain antibody (scFv-Reg4) significantly inhibited gastric cancer cell proliferation and synergistically enhanced the lethal effect of 5-FU. Thus, traditional chemo-/radio- therapeutics supplemented with scFv-Reg4 may provide advances in the strategy for gastrointestinal cancer treatment.

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Single-chain antibody-decorated Au nanocages@liposomal layer nanoprobes for targeted SERS imaging and remote-controlled photothermal therapy of melanoma cancer cells

Materials Science and Engineering C ◽

10.1016/j.msec.2021.112086 ◽

2021 ◽

Vol 124 ◽

pp. 112086

Author(s):

Ghazal Farahavar ◽

Samira Sadat Abolmaali ◽

Foroogh Nejatollahi ◽

Amin Safaie ◽

Sanaz Javanmardi ◽

...

Keyword(s):

Cancer Cells ◽

Photothermal Therapy ◽

Single Chain ◽

Single Chain Antibody ◽

Melanoma Cancer ◽

Sers Imaging

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X-ray crystallography reveals molecular recognition mechanism for sugar binding in a melibiose transporter MelB

Communications Biology ◽

10.1038/s42003-021-02462-x ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Lan Guan ◽

Parameswaran Hariharan

Keyword(s):

Molecular Recognition ◽

Binding Pocket ◽

Cation Binding ◽

Recognition Mechanism ◽

X Ray ◽

X Ray Crystallography ◽

Sugar Binding ◽

Sugar Specificity ◽

Major Facilitator ◽

Mfs Transporters

AbstractMajor facilitator superfamily_2 transporters are widely found from bacteria to mammals. The melibiose transporter MelB, which catalyzes melibiose symport with either Na+, Li+, or H+, is a prototype of the Na+-coupled MFS transporters, but its sugar recognition mechanism has been a long-unsolved puzzle. Two high-resolution X-ray crystal structures of a Salmonella typhimurium MelB mutant with a bound ligand, either nitrophenyl-α-d-galactoside or dodecyl-β-d-melibioside, were refined to a resolution of 3.05 or 3.15 Å, respectively. In the substrate-binding site, the interaction of both galactosyl moieties on the two ligands with MelBSt are virturally same, so the sugar specificity determinant pocket can be recognized, and hence the molecular recognition mechanism for sugar binding in MelB has been deciphered. The conserved cation-binding pocket is also proposed, which directly connects to the sugar specificity pocket. These key structural findings have laid a solid foundation for our understanding of the cooperative binding and symport mechanisms in Na+-coupled MFS transporters, including eukaryotic transporters such as MFSD2A.

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Computational and Rational Design of Single-Chain Antibody against Tick-Borne Encephalitis Virus for Modifying Its Specificity

Viruses ◽

10.3390/v13081494 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1494

Author(s):

Ivan K. Baykov ◽

Pavel Y. Desyukevich ◽

Ekaterina E. Mikhaylova ◽

Olga M. Kurchenko ◽

Nina V. Tikunova

Keyword(s):

Rational Design ◽

Fold Increase ◽

Encephalitis Virus ◽

Chimeric Antibody ◽

Single Chain ◽

Single Chain Antibody ◽

Glycoprotein E ◽

Tick Borne Encephalitis ◽

Tick Borne Encephalitis Virus ◽

Far Eastern

Tick-borne encephalitis virus (TBEV) causes 5−7 thousand cases of human meningitis and encephalitis annually. The neutralizing and protective antibody ch14D5 is a potential therapeutic agent. This antibody exhibits a high affinity for binding with the D3 domain of the glycoprotein E of the Far Eastern subtype of the virus, but a lower affinity for the D3 domains of the Siberian and European subtypes. In this study, a 2.2-fold increase in the affinity of single-chain antibody sc14D5 to D3 proteins of the Siberian and European subtypes of the virus was achieved using rational design and computational modeling. This improvement can be further enhanced in the case of the bivalent binding of the full-length chimeric antibody containing the identified mutation.

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