1. 1-(Acylamino)alkylphosphonic Acids-Alkaline Deacylation
Marek Cypryk, Jozef Drabowicz, Bartlomiej Gostynski, Marcin H Kudzin, Zbigniew H Kudzin, Pawel Urbaniak Molecules. 2018 Apr 9;23(4):859. doi: 10.3390/molecules23040859.
The alkaline deacylation of a representative series of 1-(acylamino)alkylphosphonic acids [(AC)-AAP: (AC) = Ac, TFA, Bz; AAP = GlyP, AlaP, ValP, PglP and PheP] in an aqueous solution of KOH (2M) was investigated. The results suggested a two-stage reaction mechanism with a quick interaction of the hydroxyl ion on the carbonyl function of the amide R-C(O)-N(H)- group in the first stage, which leads to instant formation of the intermediary acyl-hydroxyl adducts of R-C(O-)₂-N(H)-, visible in the 31P NMR spectra. In the second stage, these intermediates decompose slowly by splitting of the RC(O-)₂-N(H)- function with the subsequent formation of 1-aminoalkylphosphonate and carboxylate ions.
2. Synthesis of Imidates: TFA-Mediated Regioselective Amide Alkylation Using Meerwein's Reagent
Kirill Popov, Peter Somfai J Org Chem. 2016 Apr 15;81(8):3470-2. doi: 10.1021/acs.joc.6b00424. Epub 2016 Apr 7.
Regioselective O-alkylation of an amide to form the corresponding imidate is a common synthetic problem, often resulting in varying amounts of N-alkylation. Screening existing methods for converting amides to imidates gave inconsistent or irreproducible results, sometimes affording N-alkylamide as the major product. A simple and reliable protocol for amide O-alkylation with complete regioselectivity has been designed, and its scope and efficiency demonstrated on a number of substrates.
3. Sample Preparation by Easy Extraction and Digestion (SPEED) - A Universal, Rapid, and Detergent-free Protocol for Proteomics Based on Acid Extraction
Joerg Doellinger, Andy Schneider, Marcell Hoeller, Peter Lasch Mol Cell Proteomics. 2020 Jan;19(1):209-222. doi: 10.1074/mcp.TIR119.001616. Epub 2019 Nov 21.
The main challenge of bottom-up proteomic sample preparation is to extract proteomes in a manner that enables efficient protein digestion for subsequent mass spectrometric analysis. Today's sample preparation strategies are commonly conceptualized around the removal of detergents, which are essential for extraction but strongly interfere with digestion and LC-MS. These multi-step preparations contribute to a lack of reproducibility as they are prone to losses, biases and contaminations, while being time-consuming and labor-intensive. We report a detergent-free method, named Sample Preparation by Easy Extraction and Digestion (SPEED), which consists of three mandatory steps, acidification, neutralization and digestion. SPEED is a universal method for peptide generation from various sources and is easily applicable even for lysis-resistant sample types as pure trifluoroacetic acid (TFA) is used for highly efficient protein extraction by complete sample dissolution. The protocol is highly reproducible, virtually loss-less, enables very rapid sample processing and is superior to the detergent/chaotropic agent-based methods FASP, ISD-Urea and SP3 for quantitative proteomics. SPEED holds the potential to dramatically simplify and standardize sample preparation while improving the depth of proteome coverage especially for challenging samples.
