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Formulation of Protein- and Peptide-Based Parenteral Products
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Gaozhong Zhu, Pierre O. Souillac
Deamidation occurs through different pathways at different pH levels. In an acidic pH (2–5), deamidation occurs by direct hydrolysis, which causes Asn or Gln residue to change into Asp or Glu residue, respectively. The type of neighboring amino acids does not affect the deamidation rate. Hydrolytic mechanisms in neutral or alkaline pHs are more complex, however. Under these conditions, the side chain carbonyl group on the Asn or Gln residue reacts with the nitrogen atom on the peptide backbone to form a cyclic imide (succinimide) intermediate (Asu). Depending on which bond in the cyclic imide breaks, the reaction product can be (i) the des-amido peptide (Asp), (ii) the isopeptide (IsoAsp), or (iii) d-isomers. The formation of isopeptides is called isomerization, or sometimes referred to as transpeptidation, because an extra methylene group is inserted to the peptide backbone. When deamidation occurs, the IsoAsp to Asp ratio is typically 3. Detailed descriptions of deamidation and isomerization can be found in a review by Wakankar and Borchardt (29).
Resistance of Ashless Dispersant Additives to Oxidation and Thermal Decomposition
Published in Wilfried J. Bartz, Engine Oils and Automotive Lubrication, 2019
L. Bartha, J. Hancsok, E. Bobest
The stability of the reaction products of polyisobutenyl-succinic anhydride and pentaerythrithol and pentaerytrithol-tetraethylenepentamine mixture was between the stability of mono-, and bis-succinimide dispersants. Comparing the potential DD efficiency of the additives (Table 3.7.4) shows that polyethylene-succinimide (PEMSI), and polyisobutenil pentaerythrithol-ester have significantly lower efficiency. With other species there were NO great differences. The highest efficiency was achieved by the polyisobutenyl-succinic-anhydride-pentaerythrithol-tetraethylenepentamine reaction product. This was caused presumably by the great polar group in this dispersant which provides higher ability of adsorption to sludge particles in motor oils.
Nanocarriers in Early Diagnosis of Cancer
Published in Bhupinder Singh, Rodney J. Y. Ho, Jagat R. Kanwar, NanoBioMaterials, 2018
Gurpal Singh, Rajneet Kaur Khurana, Atul Jain, Taranvir Kaur, Bhupinder Singh
One of the most common coupling method for bioconjugation of NPs involve carboxylic group, which can react with primary amines. The most common coupling agent used here is 1-ethyl-3-(dimethylaminopropyl) carbodiimide (EDC). The EDC conjugation strategy has been applied to various proteins such as enzymes, antibodies, amine-terminated nucleic acids and small molecules with amine groups etc to carboxylic group functionalized NPs (Hermanson, 2008). Moreover, the coupling efficiency is increased by addition of stabilizing agents such as n-hydroxysuccinimide (NHS) or sulfo-NHS by formation of a succinimide ester intermediate (Figure 5.6).
Computational studies on non-succinimide-mediated stereoinversion mechanism of aspartic acid residues assisted by phosphate
Published in Molecular Physics, 2018
Tomoki Nakayoshi, Shuichi Fukuyoshi, Ohgi Takahashi, Akifumi Oda
Although the succinimide intermediate plays an important role in the stereoinversion and isomerisation of Asp residues, the results of kinetics studies suggest that there is also a non-succinimide-mediated stereoinversion pathway. Stereoinversion has also been observed in peptides in which the adjacent residue on the C-terminal side, i.e. the (N + 1) residue, of Asp is proline (Pro) [21]. However, the mechanism for non-succinimide-mediated stereoinversion of Asp residues in peptides has not yet been studied. Thus, the main focus of this study is to propose a mechanism for the direct stereoinversion of Asp residues in peptides. For the formation of succinimide by cyclisation of the Asp side chain, as shown in Scheme 1, a bond with the amide nitrogen of the (N + 1) residue is necessary. Clearly, forming a covalent bond between the Asp side chain and an adjacent main-chain Pro is impossible, and the five-membered cyclic imide structure cannot be formed in these Asp–Pro sequences. Therefore, the stereoinversion of Asp in this peptide is thought to be caused by a non-succinimide-mediated pathway. In this study, we have assumed a reaction pathway in which the Asp residue directly undergoes tautomerisation (Scheme 2) catalysed by phosphate, and estimated the activation barrier using a model compound.
Facile preparation of tertiary amine grafted poly (α,β-L-aspartic acid) with zwitterionic property to limit nonspecific protein adsorption
Published in Journal of Dispersion Science and Technology, 2021
Xiaojuan Wang, Hanqing Gu, Guolin Wu
The obtained polymer PPDMAP-PSI was further hydrolyzed under alkaline conditions to obtain zwitterionic polymer dimethylamino propyl-g-poly (α, β-aspartic acid) (DMAP-g-PAsp) with side chains containing weak acid (–COOH) and weak base group (–N(CH3)2). The FT-IR spectra were shown in Figure 3. There had no appearance of the adsorption peak of imide structure at 1795 cm−1 indicated that succinimide rings no longer existed in the polymer. With the emergence of a wide and stretching vibration adsorption peak in the range of 3400–2500 cm−1 corresponded to the O–H in the hydrogen-bonded carboxyl, together they confirmed that the ring-opening reaction of residual PSI was complete.
Improved anti-cancer effect of epidermal growth factor-gold nanoparticle conjugates by protein orientation through site-specific mutagenesis
Published in Science and Technology of Advanced Materials, 2021
The pET41a, biotinylated thrombin, and streptavidin-agarose resins were obtained from Merck (Darmstadt, Germany). The Origami™ 2 (DE3) Singles™ Competent Cells, BugBuster protein extraction reagent, and benzonase were purchased from EMD Millipore (Burlington, Massachusetts, USA). The kanamycin, isopropyl-ß-d-thiogalactopyranoside (IPTG), triethylamine, dimethyl sulfoxide (DMSO), penicillin-streptomycin solution, and bovine serum albumin (BSA) were obtained from Wako (Osaka, Japan). The glutathione sepharose 4B beads was obtained from GE-healthcare (Chicago, Illinois, USA). The anti-EGF rabbit antibody was purchased from Abcam (Cambridge, UK). The phospho-ERK1/2 (T202/Y204) rabbit monoclonal antibody was obtained from Cell Signaling Technology (Danvers, Massachusetts, USA). The dithiobis (succinimidyl undecanoate) (DSU) and 2-(N-morpholin)ethanesulfonic acid (MES) was obtained from Dojindo (Kumamoto, Japan). The ω-methoxy-poly(ethylene glycol) amine (mPEG-NH2, Mw = 5000) was obtained from NOF Corporation (Tokyo, Japan). Fifteen nm gold nanoparticle was purchased from BBI Solutions (Krumlin, UK). Fetal bovine serum (FBS) was obtained from BioWest (Nuaille, France). Cell proliferation assay kit (CellTiter 96®Aqueous Non-radioactive Cell Proliferation) was purchased from Promega (Madison, Wisconsin, USA). The 3,3ʹ,5,5ʹ-tetramethylbenzidine (TMB) was obtained from KPL (Gaithersburg, Maryland, USA). The Micro BCA™ Protein Assay Kit and N-hydroxy succinimide (NHS) were obtain from Thermo Fisher Scientific (Waltham, Massachusetts, USA). Dulbecco’s Modified Eagle’s Medium (DMEM), anti-rabbit IgG horseradish peroxidase (HRP), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), poly(ethylene glycol) 2-mercaptoethyl ether acetic acid (SH-PEG-COOH), anti-rabbit IgG alkaline phosphatase, 4-nitrophenyl phosphate disodium salt hexahydrate, and triton X-100 were obtained from Sigma-Aldrich (St. Louis, Missouri, USA). The primers: P1, P2, P3, P4, and P5 were also prepared by Sigma-Aldrich.