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Pyroglutamic acid (also known as PCA, 5-oxoproline, pidolic acid) is a ubiquitous but understudied natural amino acid derivative in which the free amino group of glutamic acid or glutamine cyclizes to form a lactam. [1] The names of pyroglutamic acid conjugate base, anion, salts, and esters are pyroglutamate, 5-oxoprolinate, or pidolate.
N-Methyl-3-piperidyl benzilate (JB-336, BZ) Piperidine is also commonly used in chemical degradation reactions, such as the sequencing of DNA in the cleavage of particular modified nucleotides. Piperidine is also commonly used as a base for the deprotection of Fmoc-amino acids used in solid-phase peptide synthesis.
Pyrrolysine (symbol Pyl or O; [2] encoded by the 'amber' stop codon UAG) is an α-amino acid that is used in the biosynthesis of proteins in some methanogenic archaea and bacteria; [3] [4] it is not present in humans. It contains an α-amino group (which is in the protonated – NH +
Electron-withdrawing substituents, such as -CF 3 group, give stronger acids (the pK a of acetic acid is 4.76 whereas trifluoroacetic acid, with a trifluoromethyl substituent, has a pK a of 0.23). Electron-donating substituents give weaker acids (the pK a of formic acid is 3.75 whereas acetic acid, with a methyl substituent, has a pK a of 4.76)
Moreover, 3-hydroxymethyl-beta-carboline blocks the sleep-promoting effect of flurazepam in rodents and – by itself – can decrease sleep in a dose-dependent manner. [16] Another derivative, methyl-β-carboline-3-carboxylate, stimulates learning and memory at low doses but can promote anxiety and convulsions at high doses. [15]
S-adenosyl-L-methionine = 1-aminocyclopropane-1-carboxylate + S-methyl-5 ′-thioadenosine. Like other PLP dependent enzymes, it catalyzes the reaction through a quinonoid zwitterion intermediate and uses cofactor pyridoxal phosphate (PLP, the active form of vitamin B6) for stabilization. [1] [2] [3]
The Knorr pyrrole synthesis is a widely used chemical reaction that synthesizes substituted pyrroles (3). [1] [2] [3] The method involves the reaction of an α-amino-ketone (1) and a compound containing an electron-withdrawing group (e.g. an ester as shown) α to a carbonyl group (2). [4] The Knorr pyrrole synthesis
Dehydration of the aldoxime to the nitrile occurs upon treatment with acetic anhydride giving 3-cyano-1-methyl-1,2,5,6-tetrahydropyridine (5). Functional group interconversion of the nitrile to the methyl carboxylate ester then occurs upon acid-catalyzed treatment in methanol, and then conversion to the HBr salt completes the synthesis.