Nicotinamide Riboside and CD38: Covalent Inhibition and Live-Cell Labeling.

Nicotinamide adenine dinucleotide (NAD) is required for a myriad of metabolic, signaling, and post-translational events in cells. Its levels in tissues and organs are closely associated with health conditions. The homeostasis of NAD is regulated by biosynthetic pathways and consuming enzymes.

Rational design of humanized antibody inhibitors for cathepsin S.

Cathepsin S (CTSS) is involved in pathogenesis of many human diseases. Inhibitors blocking its protease activity hold therapeutic potential. In comparison to small-molecule inhibitors, monoclonal antibodies capable of inhibiting CTSS enzymatic activity may possess advantageous pharmacological properties.

Eliciting anti-cancer immunity by genetically engineered multifunctional exosomes.

Exosomes are cell-derived nanovesicles involved in regulating intercellular communications. In contrast to conventional nanomedicines, exosomes are characterized by unique advantages for therapeutic development. Despite their major successes in drug delivery, the full potential of exosomes for immunotherapy remains untapped.

Expanding the toolbox of exosome-based modulators of cell functions.

Exosomes are cell-derived extracellular vesicles and play important roles in mediating intercellular communications. Due to their unique advantages in transporting a variety of biomolecules, exosomes have been emerging as a new class of nanocarriers with great potential for therapeutic applications. Despite advancements in loading chemotherapeutics and interfering RNAs into exosomes, active incorporation of protein molecules into exosomes remains challenging owing to their distinctive physicochemical properties and/or a lack of knowledge of cargo sorting during exosome biogenesis.

A two-trick pony: lysosomal protease cathepsin B possesses surprising ligase activity.

Cathepsin B is an important protease within the lysosome, where it helps recycle proteins to maintain proteostasis. It is also known to degrade proteins elsewhere but has no other known functionality. However, by carefully monitoring peptide digestion with liquid chromatography and mass spectrometry, we observed the synthesis of novel peptides during cathepsin B incubations.

Site-specific antibody-drug conjugates with variable drug-to-antibody-ratios for AML therapy.

Random conjugations of chemotherapeutics to monoclonal antibodies result in heterogeneous antibody-drug conjugates (ADCs) with suboptimal pharmacological properties. We recently developed a new technology for facile generation of homogeneous ADCs by harnessing human CD38 catalytic domain and its dinucleotide-derived covalent inhibitor, termed ADP-ribosyl cyclase-enabled ADCs (ARC-ADCs). Herein we advance this technology by designing and synthesizing ARC-ADCs with customizable drug-to-antibody ratios (DARs).

Synthesis of site-specific antibody-drug conjugates by ADP-ribosyl cyclases.

Most of the current antibody-drug conjugates (ADCs) in clinic are heterogeneous mixtures. To produce homogeneous ADCs, established procedures often require multiple steps or long reaction times. The introduced mutations or foreign sequences may cause high immunogenicity.

Rational Design of a Humanized Antibody Inhibitor of Cathepsin B.

Cathepsin B (CTSB) is an abundant cysteine protease that functions in both endolysosomal compartments and extracellular regions. A considerable number of preclinical and clinical studies indicate that CTSB is implicated in many human diseases. Expression levels and activity of CTSB significantly correlate with disease progression and severity.

A ribose-functionalized NAD with unexpected high activity and selectivity for protein poly-ADP-ribosylation.

Nicotinamide adenine dinucleotide (NAD)-dependent ADP-ribosylation plays important roles in physiology and pathophysiology. It has been challenging to study this key type of enzymatic post-translational modification in particular for protein poly-ADP-ribosylation (PARylation). Here we explore chemical and chemoenzymatic synthesis of NAD analogues with ribose functionalized by terminal alkyne and azido groups.

Chemoenzymatic Preparation of 4'-Thioribose NAD.

This chemoenzymatic procedure describes a strategy for the preparation of 4'-thioribose nicotinamide adenine dinucleotide (S-NAD ), including chemical synthesis of nicotinamide 4'-riboside (S-NR), recombinant expression and purification of two NAD biosynthesis enzymes nicotinamide riboside kinase (NRK) and nicotinamide mononucleotide adenylyltransferase (NMNAT), and enzymatic synthesis of S-NAD . The first basic protocol describes the procedures for introduction of nicotinamide onto 4'-thioribose and subsequent deprotection to generate S-NR as the key intermediate for enzymatically synthesizing S-NAD . In the second basic protocol, experimental methods are detailed for the production of recombinant human NRK1 and NMNAT1 to catalyze conversion of S-NR to S-NAD .

Facile chemoenzymatic synthesis of a novel stable mimic of NAD.

Nicotinamide adenine dinucleotide (NAD) is an essential cofactor participating in a variety of important enzyme-catalyzed physiological and pathophysiological processes. Analogues of NAD provide key and valuable agents for investigating NAD-dependent enzymes. In this study, we report the preparation of a novel stable NAD mimic, 4'-thioribose NAD (S-NAD), using a facile and efficient chemoenzymatic approach.