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Arsenals of Pharmacotherapeutically Active Proteins and Peptides: Old Wine in a New Bottle
Published in Debarshi Kar Mahapatra, Swati Gokul Talele, Tatiana G. Volova, A. K. Haghi, Biologically Active Natural Products, 2020
Ninhydrin Reaction: It was discovered by Siegfried Ruhemann in 1910 [116]. Ninhydrin is 1,2,3-indantrione monohydrate. Amino acids react with ninhydrin in the presence of pyridine to form a purple-colored complex called Ruheman’s purple. Aldehyde and carbon dioxide are also produced in this reaction [100]. Ninhydrin reaction is used for spectrophotometric estimation of amino acid with absorption maximum = 570 nm. Proline produces yellow-colored compound when subjected to ninhydrin reaction (the absorption maximum = 440 nm) [106]. Ninhydrin in Forensics: The ninhydrin reaction forms the basis of fingerprints detection in forensic science. Amino acids are released form dermal ridges of the fingers. When ninhydrin and pyridine is sprayed, the purple-colored fingerprints are observed [100].
Amino Acids, Peptides, and Proteins
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
In the initial reaction, ninhydrin reacts with the amine portion of the amino acid to produce an imine, A. This initially formed imine decarboxylates under the reaction conditions to form a new imine, B, that reacts with more ninhydrin to form the product imine (C), which is known as Ruhemann’s Purple and it absorbs strongly at 570 nm in the visible spectrum – it has a bluish-purple color. The alkyl side chain of the amino acid is lost as an aldehyde (3-methylbutanal). This reaction with ninhydrin to form C is diagnostic for amino acids that contain a primary amino function (-NH2). This reaction does not work with secondary amines. Proline, therefore, does not react with ninhydrin to give Ruhemann’s Purple, although there is a reaction.
Thin-Layer Chromatography in Clinical Chemistry
Published in Bernard Fried, Joseph Sherma, Practical Thin-Layer Chromatography, 2017
For amino acid analysis, pretreatment of sample is necessary prior to chromatographic analysis to remove proteins, lipids, inorganic salts, or other substances that interfere with chromatographic separation. Of the possible choices of stationary phases, use of cellulose is popular in most laboratories for separation of amino acids. The main advantage of using cellulose is that it gives higher chromatographic resolution in a shorter time. A large number of solvent systems have been in use for separating amino acid mixtures. The most common solvent system for separating amino acids by one-dimensional TLC30 is n-butanol–acetone–acetic acid–water (35:35:10:20, v/v), while pyridine–acetone–ammonia–water (80:60:10:35, v/v) and butan-1-ol–acetone–water–acetic acid–water (35:35:10:20, v/v) are used in two-dimensional TLC.31 The most widely used staining reagent for qualitative and quantitative assessment of amino acids is ninhydrin-collidine, a polychromatic staining reagent.
Synthesis and characterization of cationic quaternary ammonium geminis (16–s–16) and their role in ninhydrin–[Cu(II)–His]+ reaction
Published in Chemical Engineering Communications, 2021
Ninhydrin is a reagent that has been broadly employed in chemistry, forensics, bio-analytical work, and biomedical science to detect amine functionality. Ninhydrin interacts with the amine functional group and produces diketohydrindylidene–diketohydrindamine (DYDA). The utilization of this reagent depends upon the development of DYDA. DYDA becomes destabilize at room temperature, and discoloration occurs. However, several improvements have been suggested to help stabilize DYDA, such as applying conventional monomeric surfactants, changing the solvent media, and adding different inorganic and organic salts (Kabir-ud-Din et al. 1999; Khan et al. 2010). As a further improvement, the current study investigated the influence of the coordination of copper ions with the viewpoint of promoting nucleophilic attack. Consequently, the development of the DYDA product was improved.
Influence of dimeric gemini surfactant micelles on the study of nickel-glycylleucine dipeptide and ninhydrin
Published in Journal of Dispersion Science and Technology, 2020
Ninhydrin is a chemical reagent employed to recognize amino group in amino acids, peptides and proteins.[22,44,45] Ninhydrin was found much more superior over other finger print agents in detection of amino groups.[46,47] On interaction with amino acids/peptides, ninhydrin produces purple colored product diketohydrindylidene–diketohydrindamine (DYDA), frequently referred as Ruhemann’s purple.[22] Metal ion has essential role in biotic species. They catalyze and regulate chemical processes in living organism. Peptides/proteins consist significant binding sites for the connection of metal ions. Among overall interactions in nature, metal ion complex formations are the prominent one.[48,49] Metal complexes have remarkable uses in biological activities most significantly in antimicrobial, antifungal, antibacterial and anticancer activities[50,51] due to high coordination numbers and geometries. Complexation of metal ion with different ligands were used in various catalytic processes to overcame the required challenges of catalyst in most practical applications.[52,53] The chemistry of metal-coordinated amino group with ninhydrin is of great interest and demonstrates enormous biological significance and serves as a model for various biochemical reactions that take place in metabolism of deamination and transpeptidation.[54,55]
In-situ crosslinking of electrospun gelatin-carbodiimide nanofibers: fabrication, characterization, and modeling of solution parameters
Published in Chemical Engineering Communications, 2021
Maryam Hajiabbas, Iran Alemzadeh, Manouchehr Vossoughi, Amir Shamloo
Zero-length crosslinking allows researchers to immobilize protein-protein interactions without introducing a spacer arm. Carboxylates (–COOH) may be reacted to NHS or Sulfo-NHS in the presence of a carbodiimide such as EDC, resulting in a semi-stable NHS or Sulfo-NHS ester, which may then be reacted with primary amines (–NH2) to form amide crosslinks (Figure 8). Although NHS or Sulfo-NHS is not required for carbodiimide reactions, their use greatly enhances coupling efficiency (Grabarek and Gergely 1990; Staros et al. 1986). Using NHS or Sulfo-NHS makes it possible to perform a two-step reaction (Grabarek and Gergely 1990; Staros et al. 1986). Figure 8 (from Thermo Fisher Scientific) shows the mechanism of zero-length crosslinking with EDC/NHS in the presence of the carboxylate and primary amines in a protein structure to produce the stable amide bond. As, the optimum pH range for the activation of carboxyl groups using EDC is 5–6 (Grabarek and Gergely 1990; Staros et al. 1986). In this work, a small amount of acetic acid was added to reach a pH of 4 to stop crosslinking in the syringe. Also, using a higher amount of NHS (molar ratio of NHS: EDC was 2:1) leads to two-step reaction to delay the crosslinking process. Then, during electrospinning, solvent evaporation occurs, and acetic acid content in G fibers decreases. Next, by storing scaffolds in a desiccator under control humidity, EDC/NHS acted, and in-situ crosslinking in G fibers occurred. The amount of remaining free amines in the system through a ninhydrin assay was determined to measure the Degree of crosslinking. Ninhydrin readily reacts with free amines and produces a vivid purple hue upon reaction with free amine groups (Kishan et al. 2015). As depicted in Table 3, there was a small decrease in the degree of crosslinking with increasing G concentration.