Mechanism of formation of iron(ii) complexes with pentadentate ligands via C–C bond formation between trans-[Fe(2,4-bis(2-pyridylmethylimino)pentane)(MeCN)2][ClO4]2·MeCN and various nitriles

2005 ◽  
pp. 1086-1092 ◽  
Author(s):  
Hiromasa Kurosaki ◽  
Yoshinobu Ishikawa ◽  
Takao Ishihara ◽  
Teruo Yamamoto ◽  
Yoshihiro Yamaguchi ◽  
...  
Keyword(s):  
Bond Formation ◽  
Mechanism Of Formation ◽  
Pentadentate Ligands

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 Microbiological degradation of bile acids. Nitrogenous hexahydroindane derivatives formed from cholic acid by Streptomyces rubescens

1976 ◽  
Vol 160 (3) ◽  
pp. 745-755 ◽  
Author(s):  
S Hayakawa ◽  
S Hashimoto ◽  
T Onaka
Keyword(s):  
Cholic Acid ◽  
Bond Formation ◽  
Valeric Acid ◽  
Amide Bond ◽  
Side Chain ◽  
Mechanism Of Formation ◽  
Partial Synthesis ◽  
Degradative Pathway ◽  
Amide Bond Formation ◽  
New Compounds

The metabolism of cholic acid (I) by Streptomyces rubescens was investigated. This organism effected ring A cleavage, side-chain shortening and amide bond formation and gave the following metabolites: (4R)-4-[4α-(2-carboxyethyl)-3aα-hexahydro-7aβ-methyl-5-oxoindan-1 β-yl]valeric acid (IIa) and its mono-amide (valeramide) (IIb); and 2,3,4,6, 6aβ,7,8,9,9aα,9bβ-decahydro-6aβ-methyl-1H-cyclopenta[f]quinoline-3,7-dione(IIIe)and its homologues with the β-oriented side chains, valeric acid, valeramide, butanone and propionic acid, in the place of the oxo group at C-7, i.e.compounds (IIIa), (IIIb), (IIIc) and (IIId) respectively. All the nitrogenous metabolites were new compounds, and their structures were established by partial synthesis except for the metabolite (IIIc). The mechanism of formation of these metabolites is considered. A degradative pathway of cholic acid (I) into the metabolites is also tentatively proposed.

Regarding the mechanism of formation of nonmetallic inclusions conglomerates of system Al2O3-MgO

2019 ◽  
Vol 75 (12) ◽  
pp. 1341-1351
Author(s):  
A. A. Safronov ◽  
V. S. Dub ◽  
V. V. Orlov ◽  
K. L. Kosyrev ◽  
A. S. Loskutov ◽  
...  
Keyword(s):  
Nonmetallic Inclusions ◽  
Mechanism Of Formation

Assessment of ability to varnish turbine oils

2020 ◽  
Vol 06 ◽  
pp. 28-33
Author(s):  
I.V. Mitin ◽  
◽  
I.R. Tatur ◽  
K.U. Smirnov ◽  
A.M. Suloev ◽  
...  
Keyword(s):  
Antioxidant Properties ◽  
Mechanism Of Formation ◽  
Critical Situation ◽  
Antioxidant Content ◽  
Turbine Equipment

The reasons for the formation of varnish deposits of turbine oils are determined. It is shown that the performance of turbine oils is determined by methods of ASTM D7843 (MPC) and ASTM D6971 (RUL) can be assessed, the process of formation of varnish deposits, the level of antioxidant properties, antioxidant content of, amend, and extend the oil change, and to predict critical situation in the operation of turbine equipment. The mechanism of formation of varnish deposits in turbine oils is proposed.

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