Engineering disulfide bonds of the novel human β-defensins hBD-27 and hBD-28: Differences in disulfide formation and biological activity among human β-defensins

Biopolymers ◽  
2004 ◽  
Vol 80 (1) ◽  
pp. 34-49 ◽  
Author(s):  
Axel Schulz ◽  
Enno Klüver ◽  
Sandra Schulz-Maronde ◽  
Knut Adermann
Keyword(s):  
Biological Activity ◽  
Disulfide Bonds ◽  
The Novel ◽  
Disulfide Formation

Replacement of the interchain disulfide bridge-forming amino acids A7 and B7 by glutamate impairs the structure and activity of insulin

2004 ◽  
Vol 385 (12) ◽  
pp. 1171-1175 ◽  
Author(s):  
Zhan-Yun Guo ◽  
Xiao-Yuan Jia ◽  
You-Min Feng
Keyword(s):  
Biological Activity ◽  
Disulfide Bonds ◽  
Negative Charge ◽  
Disulfide Bridge ◽  
Site Directed Mutagenesis ◽  
Side Chain ◽  
Insulin Analogs ◽  
High Biological Activity ◽  
Chemical Groups ◽  
Structure And Activity

Abstract Insulin contains three disulfide bonds, one intrachain bond, A6–A11, and two interchain bonds, A7–B7 and A20–B19. Site-directed mutagenesis results (the two cysteine residues of disulfide A7–B7 were replaced by serine) showed that disulfide A7–B7 is crucial to both the structure and activity of insulin. However, chemical modification results showed that the insulin analogs still retained relatively high biological activity when A7Cys and B7Cys were modified by chemical groups with a negative charge. Did the negative charge of the modification groups restore the loss of activity and/or the disturbance of structure of these insulin analogs caused by deletion of disulfide A7–B7? To answer this question, an insulin analog with both A7Cys and B7Cys replaced by Glu, which has a long side-chain and a negative charge, was prepared by protein engineering, and its structure and activity were analyzed. Both the structure and activity of the present analog are very similar to that of the mutant with disulfide A7–B7 replaced by Ser, but significantly different from that of wild-type insulin. The present results suggest that removal of disulfide A7–B7 will result in serious loss of biological activity and the native conformation of insulin, even if the disulfide is replaced by residues with a negative charge.

Interrelationships among biological activity, disulfide bonds, secondary structure, and metal ion binding for a chemically synthesized 34-amino-acid peptide derived from α-fetoprotein

2001 ◽  
Vol 1528 (2-3) ◽  
pp. 127-134 ◽  
Author(s):  
Robert MacColl ◽  
Leslie E. Eisele ◽  
Robert F. Stack ◽  
Charles Hauer ◽  
Dilip D. Vakharia ◽  
...  
Keyword(s):  
Biological Activity ◽  
Amino Acid ◽  
Secondary Structure ◽  
Disulfide Bonds ◽  
Metal Ion ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Amino Acid Peptide

scholarly journals Substitution of lysine for arginine at position 42 of human transforming growth factor-alpha eliminates biological activity without changing internal disulfide bonds.

1989 ◽  
Vol 9 (9) ◽  
pp. 4083-4086 ◽  
Author(s):  
D Defeo-Jones ◽  
J Y Tai ◽  
G A Vuocolo ◽  
R J Wegrzyn ◽  
T L Schofield ◽  
...  
Keyword(s):  
Biological Activity ◽  
Growth Factor ◽  
Receptor Binding ◽  
Disulfide Bonds ◽  
Egf Receptor ◽  
Transforming Growth Factor ◽  
Receptor Interaction ◽  
Composition Analysis ◽  
Transforming Growth Factor Alpha ◽  
Factor Alpha

Transforming growth factor-alpha (TGF-alpha) is a growth-promoting protein that binds to the epidermal growth factor (EGF) receptor. To identify critical residues that govern TGF-alpha-EGF receptor binding, we prepared site-specific substitution mutants of TGF-alpha. Mutant proteins were tested in receptor-binding and mitogenesis assays. Semiconservative substitutions at positions 4, 12, 18, and 45 decreased biological activity 2.1- to 14-fold. The conservative substitution of lysine for arginine at position 42 completely eliminated biological activity. Amino acid composition analysis of proteolytic fragments from TGF-alpha and the Lys-42 mutant indicated that these proteins contained the same disulfide bonds. These studies suggest that arginine 42 may be a contact point for TGF-alpha-EGF receptor interaction.

Chromanones with Leishmanicidal Activity from Calea uniflora

2007 ◽  
Vol 62 (5-6) ◽  
pp. 353-356 ◽  
Author(s):  
Andréa Mendes do Nascimento ◽  
Fernanda Cristina Costa ◽  
Otavio Henrique Thiemann ◽  
Dionéia Camilo Rodrigues de Oliveira
Keyword(s):  
Biological Activity ◽  
Growth Inhibition ◽  
Leishmania Major ◽  
Spectroscopic Methods ◽  
The Novel ◽  
Leishmanicidal Activity ◽  
Significant Growth ◽  
Significant Growth Inhibition

The dichloromethane extract of Calea uniflora afforded a mixture of two novel chromanones, uniflorol-A (1) and uniflorol-B (2), and one known chromanone, 2,2-dimethyl-6- (1-hydroxyethyl)-chroman-4-one (3). The structures of these compounds were determined by spectroscopic methods. Biological activity of the compounds against Leishmania major promastigotes was evaluated. Mixture of the novel chromanones 1 and 2 showed significant growth inhibition of the parasite in the micrograms per milliliter range.

Transforming growth factor alpha: an aromatic side chain at position 38 is essential for biological activity

1989 ◽  
Vol 9 (2) ◽  
pp. 860-864
Author(s):  
E Lazar ◽  
E Vicenzi ◽  
E Van Obberghen-Schilling ◽  
B Wolff ◽  
S Dalton ◽  
...  
Keyword(s):  
Biological Activity ◽  
Growth Factor ◽  
Disulfide Bonds ◽  
Transforming Growth Factor ◽  
Site Directed Mutagenesis ◽  
Side Chain ◽  
Transforming Growth Factor Alpha ◽  
Aromatic Side Chain ◽  
Factor Alpha ◽  
Alpha Gene

Site-directed mutagenesis has been performed in the human transforming growth factor alpha gene. When tyrosine 38 is mutated into phenylalanine or tryptophane, biological activity is retained. In contrast, other alterations between cysteine 34 and cysteine 43 and disruption of disulfide bonds 8 to 21 and 34 to 43 resulted in loss of activities. The presence of an aromatic side chain at position 38 of transforming growth factor alpha seems to be essential for its activity.

Stereochemistry and biological activity of the novel narcotic analgesic fenaridine

1989 ◽  
Vol 23 (5) ◽  
pp. 395-401
Author(s):  
R. S. Vartanyan ◽  
V. O. Martirosyan ◽  
S. A. Vartanyan ◽  
A. P. Engoyan ◽  
�. V. Vlasenko ◽  
...  
Keyword(s):  
Biological Activity ◽  
Narcotic Analgesic ◽  
The Novel

scholarly journals Crystal Structure and Characterization of Human Heavy-Chain Only Antibodies Reveals a Novel, Stable Dimeric Structure Similar to Monoclonal Antibodies

Antibodies ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 66
Author(s):  
Carl Mieczkowski ◽  
Soheila Bahmanjah ◽  
Yao Yu ◽  
Jeanne Baker ◽  
Gopalan Raghunathan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Heavy Chain ◽  
Bond Formation ◽  
Therapeutic Modality ◽  
Light Chains ◽  
The Novel ◽  
Mechanism Of Formation ◽  
Disulfide Formation ◽  
Target Binding

We report the novel crystal structure and characterization of symmetrical, homodimeric humanized heavy-chain-only antibodies or dimers (HC2s). HC2s were found to be significantly coexpressed and secreted along with mAbs from transient CHO HC/LC cotransfection, resulting in an unacceptable mAb developability attribute. Expression of full-length HC2s in the absence of LC followed by purification resulted in HC2s with high purity and thermal stability similar to conventional mAbs. The VH and CH1 portion of the heavy chain (or Fd) was also efficiently expressed and yielded a stable, covalent, and reducible dimer (Fd2). Mutagenesis of all heavy chain cysteines involved in disulfide bond formation revealed that Fd2 intermolecular disulfide formation was similar to Fabs and elucidated requirements for Fd2 folding and expression. For one HC2, we solved the crystal structure of the Fd2 domain to 2.9 Å, revealing a highly symmetrical homodimer that is structurally similar to Fabs and is mediated by conserved (CH1) and variable (VH) contacts with all CDRs positioned outward for target binding. Interfacial dimer contacts revealed by the crystal structure were mutated for two HC2s and were found to dramatically affect HC2 formation while maintaining mAb bioactivity, offering a potential means to modulate novel HC2 formation through engineering. These findings indicate that human heavy-chain dimers can be secreted efficiently in the absence of light chains, may show good physicochemical properties and stability, are structurally similar to Fabs, offer insights into their mechanism of formation, and may be amenable as a novel therapeutic modality.

scholarly journals Site-specific Structural Transformation of the Novel Antifungal Cycle Depsipeptide FR901469. Synthesis and Biological Activity of FR203903.

2001 ◽  
Vol 54 (2) ◽  
pp. 193-197 ◽  
Author(s):  
AKIRA TANAKA ◽  
DAVID BARRETT ◽  
AKIHIKO FUJIE ◽  
NOBUHARU SHIGEMATSU ◽  
MICHIZANE HASHIMOTO ◽  
...  
Keyword(s):  
Biological Activity ◽  
Structural Transformation ◽  
The Novel ◽  
Site Specific

scholarly journals Identification of nonessential disulfide bonds and altered conformations in the v-sis protein, a homolog of the B chain of platelet-derived growth factor.

1988 ◽  
Vol 8 (3) ◽  
pp. 1011-1018 ◽  
Author(s):  
M K Sauer ◽  
D J Donoghue
Keyword(s):  
Biological Activity ◽  
Growth Factor ◽  
Disulfide Bonds ◽  
Polyacrylamide Gel Electrophoresis ◽  
Protein A ◽  
Sodium Dodecyl ◽  
Biologically Active ◽  
Platelet Derived Growth Factor ◽  
Wild Type ◽  
Type V

The protein encoded by v-sis, the oncogene of simian sarcoma virus, is homologous to the B chain of platelet-derived growth factor (PDGF). There are eight conserved Cys residues between PDGF-B and the v-sis protein. Both native PDGF and the v-sis protein occur as disulfide-bonded dimers, probably containing both intramolecular and intermolecular disulfide bonds. Oligonucleotide-directed mutagenesis was used to change the Cys codons to Ser codons in the v-sis gene. Four single mutants lacked detectable biological activity, indicating that Cys-127, Cys-160, Cys-171, and Cys-208 are required for formation of a biologically active v-sis protein. The other four single mutants retained biological activity as determined in transformation assays, indicating that Cys-154, Cys-163, Cys-164, and Cys-210 are dispensable for biological activity. Double and triple mutants containing three of these altered sites were constructed, some of which were transforming as well. The v-sis proteins encoded by biologically active mutants displayed significantly reduced levels of dimeric protein compared with the wild-type v-sis protein, which dimerized very efficiently. Furthermore, a mutant with a termination codon at residue 209 exhibited partial transforming activity. This study thus suggests that the minimal region required for transformation consists of residues 127 to 208. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis indicated that the v-sis proteins encoded by some of the biologically active mutants exhibited an altered conformation when compared with the wild-type v-sis protein, and suggested that Cys-154 and Cys-163 participate in a nonessential disulfide bond.

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