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Related Concept Videos

Amines to Sulfonamides: The Hinsberg Test01:23

Amines to Sulfonamides: The Hinsberg Test

3.5K
The Hinsberg test is a method to identify primary, secondary and tertiary amines, named after its pioneer, Oscar Hinsberg. Here, amines are treated with benzenesulfonyl chloride, also known as the Hinsberg reagent, in the presence of an excess of aqueous base, followed by acidification. Based on the nature of the amines, different changes are observed.
Generally, a primary amine reacts with the Hinsberg reagent to produce an N-substituted benzenesulfonamide. The electron-withdrawing...
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Structure of Amines01:19

Structure of Amines

2.6K
The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’...
2.6K
Amines to Amides: Acylation of Amines01:19

Amines to Amides: Acylation of Amines

2.5K
Various carboxylic acid derivatives (such as acid chlorides, esters, and anhydrides) can be used for the acylation of amines to yield amides. The reaction requires two equivalents of amines. The first amine molecule functions as a nucleophile and attacks the carbonyl carbon to produce a tetrahedral intermediate. This is followed by the loss of the leaving group and restoration of the C=O bond.
Next, the second equivalent of amine serves as a Brønsted base and deprotonates the quaternary...
2.5K
Acid Halides to Amides: Aminolysis01:07

Acid Halides to Amides: Aminolysis

2.8K
Aminolysis is a nucleophilic acyl substitution reaction, where ammonia or amines act as nucleophiles to give the substitution product. Acid halides react with ammonia, primary amines, and secondary amines to yield primary, secondary, and tertiary amides, respectively.
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
2.8K
Preparation of Amines: Alkylation of Ammonia and Amines01:30

Preparation of Amines: Alkylation of Ammonia and Amines

3.4K
Alkylation is one of the methods used to prepare amines. Direct alkylation of ammonia or a primary amine with an alkyl halide gives polyalkylated amines along with a quaternary ammonium salt through successive SN2 reactions. This process of making the quaternary salt through the direct alkylation method is called exhaustive alkylation.
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
3.4K
Basicity of Heterocyclic Aromatic Amines01:25

Basicity of Heterocyclic Aromatic Amines

6.1K
Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).
6.1K

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Preparation and In Vivo Use of an Activity-based Probe for N-acylethanolamine Acid Amidase
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Assessing Squarates as Amine-Reactive Probes.

Katherine I Taylor1, Jordan S Ho1, Hallie O Trial1

  • 1Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.

Journal of the American Chemical Society
|November 8, 2023
PubMed
Summary
This summary is machine-generated.

Squaric esters and squaramides act as mild electrophiles, enabling selective covalent labeling of lysine residues within protein binding sites. This selectivity is crucial for developing effective chemoproteomic probes.

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Area of Science:

  • Chemical Biology
  • Organic Chemistry
  • Biochemistry

Background:

  • Covalent probes are vital for identifying ligand-binding sites on proteins.
  • Lysine residues are abundant and attractive targets for covalent probes.
  • Achieving amine-specific and regioselective reactions with binding site lysines is a significant challenge.

Purpose of the Study:

  • To investigate the potential of squarates and squaramides as selective covalent labeling agents for lysine residues.
  • To compare the reactivity and selectivity of squarates/squaramides with other amine-reactive electrophiles.
  • To assess the utility of squarates in affinity-based chemoproteomic applications.

Main Methods:

  • Kinetic analysis of squarate and monosquaramide reactions with amines.
  • Comparison of squarate reactivity with other bioconjugation handles like N-hydroxysuccinimidyl esters.
  • Evaluation of squarate selectivity using the enzyme GlfT2 from Mycobacterium tuberculosis, which has multiple surface-exposed lysines.

Main Results:

  • Monosquaramides exhibit mild electrophilicity, favoring longer residence times for selective lysine labeling.
  • Squarate reactivity can be modulated by substituents; electron-withdrawing groups and dithionosquarates enhance reactivity.
  • N-hydroxysuccinimidyl esters react significantly faster, indicating lower selectivity.
  • Squarates demonstrated high selectivity in labeling GlfT2, primarily modifying a single lysine near a binding site, leading to covalent inhibition.

Conclusions:

  • Squaric esters and squaramides are effective and selective covalent labeling agents for lysine residues.
  • Their tunable reactivity and selectivity make them valuable tools for affinity-based chemoproteomics.
  • These findings pave the way for improved methods to identify and study protein-ligand interactions.