Amidation of methyl ester side chain bearing poly(2-oxazoline)s with tyramine: a quest for a selective and quantitative approach

2019 ◽  
Vol 10 (8) ◽  
pp. 954-962 ◽  
Author(s):  
Joachim F. R. Van Guyse ◽  
Maarten A. Mees ◽  
Maarten Vergaelen ◽  
Mathijs Baert ◽  
Bart Verbraeken ◽  
...  
Keyword(s):  
Methyl Ester ◽  
Quantitative Approach ◽  
Side Chain

Three new amidation approaches are evaluated to incorporate tyramine on methyl ester functional poly(2-oxazolines).

Synthesis of oxytocin analogues modified in the tripeptide side-chain by condensation of aminoterminal linear hexapeptide with the carboxyterminal tripeptide

1979 ◽  
Vol 44 (1) ◽  
pp. 275-287 ◽  
Author(s):  
Jan Hlaváček ◽  
Tomislav Barth ◽  
Karel Bláha ◽  
Karel Jošt
Keyword(s):  
Methyl Ester ◽  
Side Chain ◽  
Glycine Methyl Ester

For the synthesis of oxytocin (Ia) analogues modified in the carboxyterminal part of the molecule, a method based on the condensation of protected aminoterminal hexapeptide with tripeptides by the action of dicyclohexylcarbodiimide and pentafluorophenol in the presence of 1-hydroxybenzotriazole was devised. Using this method [7-[U-13C]proline]oxytocin (Ib), des-9-glycine-oxytocin (Ic) and methyl ester of oxytocinoic acid ([9-glycine methyl ester]oxytocin) (Id) were prepared.

Volume phase transition induced by temperature sensitive DL-amino acid methyl ester side chain based copolymer gels

2000 ◽  
Vol 3 (3) ◽  
pp. 381-387 ◽  
Author(s):  
Akihiro Hiroki ◽  
Hideaki Iwakami ◽  
Masaru Yoshida ◽  
Takeshi Suwa ◽  
Masaharu Asano ◽  
...  
Keyword(s):  
Phase Transition ◽  
Amino Acid ◽  
Methyl Ester ◽  
Acid Methyl Ester ◽  
Side Chain ◽  
Temperature Sensitive ◽  
Volume Phase Transition ◽  
Volume Phase ◽  
Acid Methyl ◽  
Amino Acid Methyl Ester

The Inactivation of Penicillopepsin with l,2-Epoxy-3-(p-nitrophenoxy)propane, an Active-Site Directed Reagent

1974 ◽  
Vol 52 (11) ◽  
pp. 1018-1023 ◽  
Author(s):  
G. Mains ◽  
T. Hofmann
Keyword(s):  
Methyl Ester ◽  
Aspartic Acid ◽  
Active Site ◽  
Side Chain ◽  
Porcine Pepsin ◽  
Protein Inactivation ◽  
Pepsin Inhibitor

Penicillopepsin was fully inactivated by the pepsin inhibitor 1,2-epoxy-3-(p-nitrophenoxy) propane, and 1.3 ± 0.3 mol of reagent became associated with each mole of protein. Inactivation was more rapid at pH 3.0 than at pH 6.0. Approximately 1 equivalent of the bound reagent was esterified to an aspartic acid side chain. Enzyme previously inactivated with diazoacetylnorleucine methyl ester did not react with the epoxide; and enzyme that was first inactivated with the epoxide did not react with the diazo inhibitor. The results add further evidence for the enzymatic similarity of porcine pepsin and penicillopepsin.

scholarly journals Alteration of Leucine Aminopeptidase from Streptomyces septatus TH-2 to Phenylalanine Aminopeptidase by Site-Directed Mutagenesis

2005 ◽  
Vol 71 (11) ◽  
pp. 7229-7235 ◽  
Author(s):  
Jiro Arima ◽  
Yoshiko Uesugi ◽  
Masaki Iwabuchi ◽  
Tadashi Hatanaka
Keyword(s):  
Methyl Ester ◽  
Leucine Aminopeptidase ◽  
Hydrolytic Activity ◽  
Site Directed Mutagenesis ◽  
Saturation Mutagenesis ◽  
Side Chain ◽  
Directed Mutagenesis ◽  
Wild Type ◽  
Peptide Substrates ◽  
Hydrolytic Activities

ABSTRACT To tailor leucine aminopeptidase from Streptomyces septatus TH-2 (SSAP) to become a convenient biocatalyst, we are interested in Phe221 of SSAP, which is thought to interact with the side chain of the N-terminal residue of the substrate. By using saturation mutagenesis, the feasibility of altering the performance of SSAP was evaluated. The hydrolytic activities of 19 mutants were investigated using aminoacyl p-nitroanilide (pNA) derivatives as substrates. Replacement of Phe221 resulted in changes in the activities of all the mutants. Three of these mutants, F221G, F221A, and F221S, specifically hydrolyzed l-Phe-pNA, and F221I SSAP exhibited hydrolytic activity with l-Leu-pNA exceeding that of the wild type. Although the hydrolytic activities with peptide substrates decreased, the hydrolytic activities with amide and methyl ester substrates were proportional to the changes in the hydrolytic activities with pNA derivatives. Furthermore, based on a comparative kinetic study, the mechanism underlying the alteration in the preference of SSAP from leucine to phenylalanine is discussed.

Mechanism of Rubber Coagent Peroxide Cure System

1970 ◽  
Vol 43 (3) ◽  
pp. 613-623 ◽  
Author(s):  
J. A. Cornell ◽  
A. J. Winters ◽  
L. Halterman
Keyword(s):  
Methyl Ester ◽  
Hydrogen Abstraction ◽  
Addition Product ◽  
Side Chain ◽  
Dicumyl Peroxide ◽  
Experimental Conditions ◽  
Branched Hydrocarbons ◽  
Similar Product ◽  
Ethylene Dimethacrylate ◽  
Single Addition

Abstract Peroxide vulcanization mechanisms of curing natural and synthetic rubbers have been extensively investigated. Little work has been reported on the use of polyfunctional monomers as coagents. Utilizing a model hydrocarbon, decane, with dicumyl peroxide and a methacrylate ester monomer, the mechanism for vulcanization in polyethylene is postulated. In the absence of the monomer, the dicumyl peroxide has been shown to abstract a hydrogen from the backbone —CH2— to form a radical. This radical terminates with another radical similarly formed to produce a crosslink. With n-decane, C20 dimers are formed. On the addition of a methacrylate ester, the hydrogen abstraction appears to still take place, but the methacrylate is added to the radical. This is not a typical polymerization initiation since the chain length of the methacrylate side chain is extremely short. Depending on the concentration, it may be limited to a single addition product. Using methyl methacrylate, infrared and nuclear magnetic resolution spectra confirm this addition product under experimental conditions. A similar product was also obtained when ethylene dimethacrylate was reacted, hydrolyzed, and re-esterified to the methyl ester. Comparative products using branched hydrocarbons indicated that tertiary hydrogens were also abstracted. Comparison of IR spectra obtained in a peroxide coagent vulcanization of polyethylene indicated the lack of polymethacrylate absorption. This curve is similar to that obtained with the decane, but quite different from that obtained with a mixed polymer of polyethylene and polymethyl methacrylate or polyethylene dimethacrylate.

Collision-Induced Dissociations of Deprotonated Dipeptide Methyl Esters Containing Serine or Threonine

1994 ◽  
Vol 47 (10) ◽  
pp. 1851 ◽  
Author(s):  
ST Steinborner ◽  
AM Bradford ◽  
RJ Waugh ◽  
JH Bowie ◽  
DL Vollmer ◽  
...  
Keyword(s):  
Methyl Ester ◽  
Mass Spectra ◽  
Methyl Esters ◽  
Side Chain ◽  
Backbone Cleavage ◽  
Sequencing Data ◽  
Deuterium Labelling ◽  
Product Ions

The collision-induced mass spectra (MS/MS) of (M - H)- ions derived from dipeptide methyl esters containing serine or threonine lack the characteristic backbone cleavage of the underivatized peptides (which provide primary sequencing data). Instead, competitive fragmentation occurs through the ester and α-side chain functions. For example, Ser methyl esters lose both CH2O (from the side chain) and MeOH ( MeO comes from the methyl ester). Isomeric dipeptides may be differentiated by competitive fragmentations; for example [ Gly Ser( OMe )-H]- fragments first by loss of CH2O, while [Ser Gly ( OMe )-H]-, in contrast, shows initial elimination of MeOH. The structures of the product ions in these spectra have been probed by deuterium labelling and MS/MS/MS studies.

scholarly journals Bioactive Steroids with Methyl Ester Group in the Side Chain from a Reef Soft Coral Sinularia brassica Cultured in a Tank

Marine Drugs ◽  
2017 ◽  
Vol 15 (9) ◽  
pp. 280 ◽  
Author(s):  
Chiung-Yao Huang ◽  
Jui-Hsin Su ◽  
Chih-Chuang Liaw ◽  
Ping-Jyun Sung ◽  
Pei-Lun Chiang ◽  
...  
Keyword(s):  
Methyl Ester ◽  
Soft Coral ◽  
Ester Group ◽  
Side Chain
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