Enzyme Engineering Renders Chlorinase the Activity of Fluorinase

Enzymatic Reactions of S-Adenosyl-L-Methionine: Synthesis and Applications

S-adenosyl-L-methionine (SAM, AdoMet) is a ubiquitous biomolecule present in all living organisms, playing a central role in a wide array of biochemical reactions and intracellular regulatory pathways. It is the second most common participant in enzymatic reactions in living systems, following adenosine triphosphate (ATP). This review provides a comprehensive analysis of enzymatic reactions involving SAM, whether as a product, a reactant (cosubstrate), or as a non-consumable enzyme cofactor. The discussion encompasses various methods for SAM synthesis, including biotechnological, chemical, and enzymatic approaches. Particular emphasis is placed on the biochemical reactions where SAM functions as a cosubstrate, notably in trans-alkylation reactions, where it acts as a key methyl group donor. Beyond methylation, SAM also serves as a precursor for the synthesis of other molecular building blocks, which are explored in a dedicated section. The review also addresses the role of SAM as a non-consumable cofactor in enzymatic processes, highlighting its function as a prosthetic group for certain protein enzymes and its ability to form complexes with ribozymes. In addition, bioorthogonal systems involving SAM analogues are discussed. These systems employ engineered enzyme-cofactor pairs designed to enable highly selective interactions between target SAM analogues and specific enzymes, facilitating precise reactions even in the presence of other SAM-dependent enzymes. The concluding section explores practical applications of SAM analogues, including their use as selective inhibitors in clinical medicine and as components of reporter systems.

Switchable CO2-Responsive Janus Nanoparticle for Lipase Catalysis in Pickering Emulsion

The use of convertible immobilized enzyme carriers is crucial for biphasic catalytic reactions conducted in Pickering emulsions. However, the intense mechanical forces during the conversion process lead to enzyme leakage, affecting the stability of the immobilized enzymes. In this study, a CO2-responsive switchable Janus (CrSJ) nanoparticle (NP) was developed using silica NP, with one side featuring aldehyde groups and the other side adsorbing N,N-dimethyldodecylamine. A switchable Pickering emulsion catalytic system for biphasic interface reactions was prepared by covalently immobilizing lipase onto the CrSJ NPs. The CO2-responsive nature of the CrSJ NPs allowed for rapid conversion of the Pickering emulsion, and covalent immobilization substantially reduced lipase leakage while enhancing the stability of the immobilization during the conversion process. Impressively, after repeated transformations, the Pickering emulsion still maintains its original structure. Following 10 consecutive cycles of esterification and hydrolysis reactions, the immobilized enzyme's activity remains at 77.7 and 79.5% of its initial activity, respectively. The Km of the CrSJ catalytic system showed no significant change compared to the free enzyme, while its Vmax values were 1.2 and 1.6 times that of the free enzyme in esterification and hydrolysis reactions, respectively.