Ammonolysis mediated side reactions of β-tert-butyl aspartyl peptides

1989 ◽  
Vol 54 (12) ◽  
pp. 3360-3373 ◽  
Author(s):  
István Schön ◽  
Attila Rill
Keyword(s):  
Side Reactions ◽  
Complex Mechanism ◽  
Tert Butyl ◽  
Aspartyl Peptides

Ammonolysis of Z-Asp(OBut)-Phe-NH2 and Boc-Leu-Asp(OBut)-Phe-NH2, as well as their diastereomers, resulted not only in transpeptidated, but also in epimerized peptides through a complex mechanism. Key compounds of these transformations are presumably very reactive cyclic aminosuccinyl derivatives. In some cases, the amount of α-peptide formed approached that of the β-peptide, in one case it exceeded this amount.

scholarly journals DFT Study On Reaction Mechanism of Di-tert-butyl Phenol to Di-tert-butyl Hydroxybenzoic Acid

2021 ◽  
Author(s):  
Nengzhi Jin ◽  
Qi-Bin Zhang ◽  
Rong Liu ◽  
Pan-Pan Zhou
Keyword(s):  
Main Product ◽  
Dynamic Equilibrium ◽  
Experimental Studies ◽  
Side Product ◽  
Side Reactions ◽  
Activation Energy Barrier ◽  
Tert Butyl ◽  
Lower Activation ◽  
Butyl Phenol ◽  
Shed Light

Abstract Experimental studies on the Kolbe-Schmitt reaction and its side reactions have made great progresses, however the relative theoretical studies fall behind. In order to study the mechanism of Kolbe-Schmitt reaction with 2,6-di-tert-butylphenol and 2,4-di-tert-butylphenol as reactants, we carried out theoretical calculation studies at M06-2X/Def2-SVP/SMD level of theory using Gaussian 09 D.01 software package. For the reactant 2,6-di-tert-butylphenol, the main product and side product can convert to each other due to the dynamic equilibrium. However for 2,4-di-tert-butylphenol, the main product is thermodynamically favorable due to its lower Gibbs free energy, while the side product is kinetically favorable due to the lower activation energy barrier. We hope the study can shed light on Kolbe-Schmitt reaction.

Aldehyde gold clusters for molecular labeling

1995 ◽  
Vol 53 ◽  
pp. 858-859
Author(s):  
James F. Hainfeld ◽  
Frederic R. Furuya
Keyword(s):  
Covalent Bond ◽  
Aldehyde Group ◽  
Gold Clusters ◽  
Side Reactions ◽  
Amino Groups ◽  
Sodium Cyanoborohydride ◽  
Schiff’S Base ◽  
Protein Molecules ◽  
Hydroxysuccinimide Esters ◽  
Primary Amino

Glutaraldehyde is a useful tissue and molecular fixing reagents. The aldehyde moiety reacts mainly with primary amino groups to form a Schiff's base, which is reversible but reasonably stable at pH 7; a stable covalent bond may be formed by reduction with, e.g., sodium cyanoborohydride (Fig. 1). The bifunctional glutaraldehyde, (CHO-(CH2)3-CHO), successfully stabilizes protein molecules due to generally plentiful amines on their surface; bovine serum albumin has 60; 59 lysines + 1 α-amino. With some enzymes, catalytic activity after fixing is preserved; with respect to antigens, glutaraldehyde treatment can compromise their recognition by antibodies in some cases. Complicating the chemistry somewhat are the reported side reactions, where glutaraldehyde reacts with other amino acid side chains, cysteine, histidine, and tyrosine. It has also been reported that glutaraldehyde can polymerize in aqueous solution. Newer crosslinkers have been found that are more specific for the amino group, such as the N-hydroxysuccinimide esters, and are commonly preferred for forming conjugates. However, most of these linkers hydrolyze in solution, so that the activity is lost over several hours, whereas the aldehyde group is stable in solution, and may have an advantage of overall efficiency.

Inhibition of Fibrinolysis and Fibrinogenolysis in Man: Comparison of ε-Aminocaproic Acid and Kallikrein Inhibitor

1963 ◽  
Vol 10 (01) ◽  
pp. 106-119 ◽  
Author(s):  
E Beck ◽  
R Schmutzler ◽  
F Duckert ◽  
Keyword(s):  
Aminocaproic Acid ◽  
Side Reactions ◽  
In Vitro Tests ◽  
Factor V ◽  
Clinical Use ◽  
Strong Inhibitor ◽  
Kallikrein Inhibitor ◽  
Therapeutic Possibilities

SummaryInhibitor of kallikrein and trypsin (KI) extracted from bovine parotis was compared with ε-aminocaproic acid (EACA): both substances inhibit fibrinolysis induced with streptokinase. EACA is a strong inhibitor of fibrinolysis in concentrations higher than 0, 1 mg per ml plasma. The same amount and higher concentrations are not able to inhibit completely the proteolytic-side reactions of fibrinolysis (fibrinogenolysis, diminution of factor V, rise of fibrin-polymerization-inhibitors). KI inhibits well proteolysis of plasma components in concentrations higher than 2,5 units per ml plasma. Much higher amounts of KI are needed to inhibit fibrinolysis as demonstrated by our in vivo and in vitro tests.Combination of the two substances for clinical use is suggested. Therapeutic possibilities are discussed.

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