Monodisperse Chemical Oligophosphorylation of Peptides via Protected Oligophosphorimidazolide Reagents.

Protein poly- and oligophosphorylation are recently discovered post-translational modifications that remain poorly characterized due to (1) the difficulty of extracting endogenously polyphosphorylated species without degradation and (2) the absence of synthetic and analytical tools to prepare and characterize poly- and oligophosphorylated species in biochemical contexts. Herein, we report a methodology for the selective oligophosphorylation of peptides with monodisperse phosphate chain lengths (P=3-6). A library of oligophosphorimidazolide (oligoP-imidazolide) reagents featuring benzyl and o-nitrophenylethyl protecting groups was synthesized in moderate-to-good yields (65-93 %).

Dietary control of peripheral adipose storage capacity through membrane lipid remodelling.

Complex genetic and dietary cues contribute to the development of obesity, but how these are integrated on a molecular level is incompletely understood. Here, we show that PPARγ supports hypertrophic expansion of adipose tissue via transcriptional control of LPCAT3, a membrane-bound O-acyltransferase that enriches diet-derived omega-6 ( -6) polyunsaturated fatty acids (PUFAs) in the phospholipidome. In high-fat diet-fed mice, lowering membrane -6 PUFA levels by adipocyte-specific knockout ( ) or by dietary lipid manipulation leads to dysfunctional triglyceride (TG) storage, ectopic fat deposition and insulin resistance.

Pentaphosphorylation via the Anhydride of Dihydrogen Pentametaphosphate: Access to Nucleoside Hexa- and Heptaphosphates and Study of Their Interaction with Ribonuclease A.

Pentametaphosphate is the little studied cyclic pentamer of the metaphosphate ion, [PO] . We show that the doubly protonated form of this pentamer can be selectively dehydrated to provide the anhydride [PO] (). This trianion is the well-defined condensed phosphate component of a novel reagent for attachment of a pentaphosphate chain to biomolecules all in one go.

Stabilized Molecular Diphosphorus Pentoxide, POL (L = -Donor Base), in the Synthesis of Condensed Phosphate-Organic Molecule Conjugates.

Commercial phosphorus pentoxide reacts with some -donor bases to give the adducts POL and POL (L = DABCO, pyridine, 4--butylpyridine). The DABCO adducts were structurally characterized by single-crystal X-ray diffraction. It is proposed that POL and POL undergo interconversion through a "phosphate-walk" mechanism, which was evaluated using DFT calculations.

Narratives of Undergraduate Research, Mentorship, and Teaching at UCLA.

This work describes select narratives pertaining to undergraduate teaching and mentorship at UCLA Chemistry and Biochemistry by Alex Spokoyny and his junior colleagues. Specifically, we discuss how individual undergraduate researchers contributed and jump-started multiple research themes since the conception of our research laboratory. This work also describes several recent innovations in the inorganic and general chemistry courses taught by Spokoyny at UCLA with a focus of nurturing appreciation for research and creative process in sciences including the use of social media platforms.

Sterically Unprotected Nucleophilic Boron Cluster Reagents.

A cornerstone of modern synthetic chemistry rests on the ability to manipulate the reactivity of a carbon center by rendering it either electrophilic or nucleophilic. However, accessing a similar reactivity spectrum with boron-based reagents has been significantly more challenging. While classical nucleophilic carbon-based reagents normally do not require steric protection, readily accessible, unprotected boron-based nucleophiles have not yet been realized.

Precursor reaction kinetics control compositional grading and size of CdSe S nanocrystal heterostructures.

We report a method to control the composition and microstructure of CdSe S nanocrystals by the simultaneous injection of sulfide and selenide precursors into a solution of cadmium oleate and oleic acid at 240 °C. Pairs of substituted thio- and selenoureas were selected from a library of compounds with conversion reaction reactivity exponents ( ) spanning 1.3 × 10 s to 2.

Heisenberg-scaling measurement protocol for analytic functions with quantum sensor networks.

We generalize past work on quantum sensor networks to show that, for input parameters, entanglement can yield a factor () improvement in mean-squared error when estimating an analytic function of these parameters. We show that the protocol is optimal for qubit sensors, and we conjecture an optimal protocol for photons passing through interferometers. Our protocol is also applicable to continuous variable measurements, such as one quadrature of a field operator.

Transcriptional regulation of -GlcNAc homeostasis is disrupted in pancreatic cancer.

Many intracellular proteins are reversibly modified by -linked GlcNAc (-GlcNAc), a post-translational modification that dynamically regulates fundamental cellular processes in response to diverse environmental cues. Accumulating evidence indicates that both excess and deficiency of protein -GlcNAcylation can have deleterious effects on the cell, suggesting that maintenance of -GlcNAc homeostasis is essential for proper cellular function. However, the mechanisms through which -GlcNAc homeostasis is maintained in the physiologic state and altered in the disease state have not yet been investigated.

Transcriptional regulation of macrophage cholesterol efflux and atherogenesis by a long noncoding RNA.

Nuclear receptors regulate gene expression in response to environmental cues, but the molecular events governing the cell type specificity of nuclear receptors remain poorly understood. Here we outline a role for a long noncoding RNA (lncRNA) in modulating the cell type-specific actions of liver X receptors (LXRs), sterol-activated nuclear receptors that regulate the expression of genes involved in cholesterol homeostasis and that have been causally linked to the pathogenesis of atherosclerosis. We identify the lncRNA MeXis as an amplifier of LXR-dependent transcription of the gene Abca1, which is critical for regulation of cholesterol efflux.

Calcium-dependent O-GlcNAc signaling drives liver autophagy in adaptation to starvation.

Starvation induces liver autophagy, which is thought to provide nutrients for use by other organs and thereby maintain whole-body homeostasis. Here we demonstrate that O-linked β-N-acetylglucosamine (O-GlcNAc) transferase (OGT) is required for glucagon-stimulated liver autophagy and metabolic adaptation to starvation. Genetic ablation of OGT in mouse livers reduces autophagic flux and the production of glucose and ketone bodies.

Protein O-GlcNAcylation: emerging mechanisms and functions.

O-GlcNAcylation - the attachment of O-linked N-acetylglucosamine (O-GlcNAc) moieties to cytoplasmic, nuclear and mitochondrial proteins - is a post-translational modification that regulates fundamental cellular processes in metazoans. A single pair of enzymes - O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) - controls the dynamic cycling of this protein modification in a nutrient- and stress-responsive manner. Recent years have seen remarkable advances in our understanding of O-GlcNAcylation at levels that range from structural and molecular biology to cell signalling and gene regulation to physiology and disease.

Vasoreparative dysfunction of CD34+ cells in diabetic individuals involves hypoxic desensitization and impaired autocrine/paracrine mechanisms.

We hypothesized that endothelial progenitor cells derived from individuals with diabetes would exhibit functional defects including inability to respond to hypoxia and altered paracrine/autocrine function that would impair the angiogenic potential of these cells. Circulating mononuclear cells isolated from diabetic (n = 69) and nondiabetic (n = 46) individuals were used to grow endothelial colony forming cells (ECFC), early endothelial progenitor cells (eEPCs) and isolate CD34+ cells. ECFCs and eEPCs were established from only 15% of the diabetic individuals tested thus directing our main effort toward examination of CD34+ cells.

Small molecule activation of PKM2 in cancer cells induces serine auxotrophy.

Proliferating tumor cells use aerobic glycolysis to support their high metabolic demands. Paradoxically, increased glycolysis is often accompanied by expression of the lower activity PKM2 isoform, effectively constraining lower glycolysis. Here, we report the discovery of PKM2 activators with a unique allosteric binding mode.

O-GlcNAc transferase/host cell factor C1 complex regulates gluconeogenesis by modulating PGC-1α stability.

A major cause of hyperglycemia in diabetic patients is inappropriate hepatic gluconeogenesis. PGC-1α is a master regulator of gluconeogenesis, and its activity is controlled by various posttranslational modifications. A small portion of glucose metabolizes through the hexosamine biosynthetic pathway, which leads to O-linked β-N-acetylglucosamine (O-GlcNAc) modification of cytoplasmic and nuclear proteins.

Benzimidazolone as potent chymase inhibitor: modulation of reactive metabolite formation in the hydrophobic (P1) region.

A new class of chymase inhibitor featuring a benzimidazolone core with an acid side chain and a P(1) hydrophobic moiety is described. Incubation of the lead compound with GSH resulted in the formation of a GSH conjugate on the benzothiophene P(1) moiety. Replacement of the benzothiophene with different heterocyclic systems such as indoles and benzoisothiazole is feasible.

Discovery and characterization of the N-phenyl-N'-naphthylurea class of p38 kinase inhibitors.

An effort aimed at exploring structural diversity in the N-pyrazole-N'-naphthylurea class of p38 kinase inhibitors led to the synthesis and characterization of N-phenyl-N'-naphthylureas. Examples of these compounds displayed excellent inhibition of TNF-alpha production in vitro, as well as efficacy in a mouse model of lipopolysaccharide induced endotoxemia. In addition, perspective is provided on the role of a sulfonamide functionality in defining inhibitor potency.

Hit to lead account of the discovery of a new class of inhibitors of Pim kinases and crystallographic studies revealing an unusual kinase binding mode.

A series of inhibitors of Pim-2 kinase identified by high-throughput screening is described. Details of the hit validation and lead generation process and structure-activity relationship (SAR) studies are presented. Disclosure of an unconventional binding mode for 1, as revealed by X-ray crystallography using the highly homologous Pim-1 protein, is also presented, and observed binding features are shown to correlate with the Pim-2 SAR.

Discovery and optimization of p38 inhibitors via computer-assisted drug design.

Integration of computational methods, X-ray crystallography, and structure-activity relationships will be disclosed, which lead to a new class of p38 inhibitors that bind to p38 MAP kinase in a Phe out conformation.

New modifications to the area of pyrazole-naphthyl urea based p38 MAP kinase inhibitors that bind to the adenine/ATP site.

Discovery of the pyrazole-naphthyl urea class of p38 MAP kinase inhibitors typified by the clinical candidate BIRB 796 has encouraged further exploration of this particular scaffold. Modification to the part of the inhibitor that occupies the adenine/ATP binding site has resulted in a new way to obtain potent inhibitors that possess favorable in vitro and in vivo properties.

Discovery and design of benzimidazolone based inhibitors of p38 MAP kinase.

A new class of benzimidazolone p38 MAP kinase inhibitors was discovered through high-throughput screening. X-ray crystallographic data of the lead molecule with p38 were used to design analogues with improved binding affinity and potency in a cell assay of LPS-induced TNFalpha production. Herein, we report the SAR of this new class of p38 inhibitors.

Expression, purification, crystallization and preliminary crystallographic analysis of human Pim-1 kinase.

Pim kinases, including Pim-1, Pim-2 and Pim-3, belong to a distinctive serine/threonine protein-kinase family. They are involved in cytokine-induced signal transduction and the development of lymphoid malignancies. Their kinase domains are highly homologous to one another, but share low sequence identity to other kinases.