Malt carboxypeptidase catalyzes the formation of peptide bonds using N-benzoyl-arginine esters as acyl components and amino acid amides or amino acid methyl esters as nucleophiles. With seven different nucleophiles yields of 5095% were obtained while no aminolysis was observed with H-Pro-NH2 and H-GIu-a-NH2. The enzyme is easily saturated with nucleophile indicating the formation of a complex b...

Divalent metal ions promote hydrolysis of RNA backbones generating 5'OH and 2';3'P as cleavage products. In these reactions, the neighboring 2'OH act as the nucleophile. RNA catalyzed reactions also require divalent metal ions and a number of different metal ions function in RNA mediated cleavage of RNA. In one case, the LZV leadzyme, it was shown that this catalytic RNA requires lead for catal...

Polyhydroxybutyrate (PHB) synthases catalyze the conversion of beta-hydroxybutyryl coenzyme A (HBCoA) to PHB. These enzymes require an active site cysteine nucleophile for covalent catalysis. A protein BLASTp search using the Class III Chromatium vinosum synthase sequence reveals high homology to prokaryotic lipases whose crystal structures are known. The homology is very convincing in the alph...

The human immunodeficiency virus integrase (HIV IN) protein cleaves two nucleotides off the 3' end of viral DNA and subsequently integrates the viral DNA into target DNA. IN exposes a specific phosphodiester bond near the viral DNA end to nucleophilic attack by water or other nucleophiles, such as glycerol or the 3' hydroxyl group of the viral DNA molecule itself. Wild-type IN has a preference ...

Recent studies have shown that a number of glycoside hydrolase families do not follow the classical catalytic mechanisms, as they lack a typical catalytic base/ nucleophile. A variety of mechanisms are used to replace this function, including substrate-assisted catalysis, a network of several residues, and the use of non-carboxylate residues or exogenous nucleophiles. Removal of the catalytic b...

A new attractive interaction in metalloprotein structures, between the thiolate anion of a metal-bound cysteine (acting as a nucleophile) and a carbonyl carbon of a peptide group (an electrophile), has been identified. From 82 cases extracted from 23 metalloprotein structures, the interacting S and C atoms are found to be at a distance of 3.2 (+/-2) A, such that the angle S ... C-O is 109 degre...

The full scope and limitations of solution and solid phase one-pot three component Nacyliminium ion reactions are detailed. After studying the scope in solution with respect to the carbamate, nucleophile and aldehyde component, a ‘translation’ was made to the solid phase. The solid phase reactions were eventually carried out using the so-called SEC linker system, which was previously developed ...

The 1,6-conjugate addition of nucleophiles to dienyl diketones produces either cyclopentenone or 2H-pyran products with high selectivity through either Nazarov (4π) or 6π electrocyclization, respectively. The outcome of the reaction is dependent upon the nature of the nucleophile used. Nucleophiles that are anionic or easily deprotonated exclusively produce cyclopentenones via Nazarov cyclizati...