Vivek S. Bharadwaj

• PhD Chemical Engineering
• Staff-Scientist at National Renewable Energy Laboratory

Biological routes to the production of fuels from renewable feedstocks hold significant promise in our efforts towards a sustainable future. The fatty acid decarboxylase enzyme (OleTJE) is a cytochrome P450 enzyme that converts long and medium chain fatty acids to terminal alkenes and shares significant similarities in terms of structure, substrate...

Significance Cellulose plays an important role as a structural polymer for natural material applications and as a source of sugars for production of renewable fuels and chemicals. Previously, kink defects have been observed in isolated cellulose nanofibrils. In this work, we provide direct evidence that these defects can be induced by mechanical de...

Family 45 glycoside hydrolases (GH45) are endoglucanases that are integral to cellulolytic secretomes, and their ability to break down cellulose has been successfully exploited in textile and detergent industries. In addition to their industrial relevance, understanding the molecular mechanism of GH45-catalyzed hydrolysis is of fundamental importan...

Charging large format lithium ion batteries within ten to fifteen minutes requires changes to the electrolyte composition in addition to modification of electrode and cell architectures. Several approaches to address this need have been proposed; but there is not a lot of clarity on understanding what factors limit the performance of existing elect...

Substrate specificity is an essential characteristic of any enzyme's function and an understanding of the factors that determine this specificity is crucial for enzyme engineering. Unlike the structure of an enzyme which is directly impacted by its sequence, substrate specificity as an enzyme attribute involves a rather indirect relationship with s...

Polysaccharides are a class of important biomolecules whose structure and function are dictated by the specific sequence of, and linkage between individual constituent carbohydrate residues. Rhamnogalacturonan-II (RG-II) is the most complex polysaccharide known in Nature and plays an indispensable role in the growth and development of all vascular...

Plant secondary cell walls (SCWs) are composed of a heterogeneous interplay of three major biopolymers: cellulose, hemicelluloses, and lignin. Details regarding specific intermolecular interactions and higher-order architecture of the SCW superstructure remain ambiguous. Here, we use solid-state nuclear magnetic resonance (ssNMR) measurements to in...

Glycosyltransferases (GTs) are carbohydrate-active enzymes that are encoded by the genomes of organisms spanning all domains of life. GTs catalyze glycosidic bond formation, transferring a sugar monomer from an activated donor to an acceptor substrate, often another saccharide. GTs from family 47 (GT47, PF03016) are involved in the synthesis of com...

Rhamnogalacturonan I (RGI) is a structurally complex pectic polysaccharide with a backbone of alternating rhamnose and galacturonic acid residues substituted with arabinan and galactan side chains. Galactan synthase 1 (GalS1) transfers galactose and arabinose to either extend or cap the β-1,4-galactan side chains of RGI, respectively. Here we repor...

The [FeFe]-hydrogenases are enzymes that catalyze the reversible activation of H2 coupled to the reduction–oxidation of electron carriers. Members of the different taxonomic groups of [FeFe]-hydrogenases display a wide range of preference, or bias, for H2 oxidation or H2 production reactions, despite sharing a common catalytic cofactor, or H-cluste...

Rhamnogalacturonan I (RGI) is a structurally complex pectic polysaccharide with a backbone of alternating rhamnose and galacturonic acid residues substituted with arabinan and galactan side chains. Galactan synthase 1 (GalS1), transfers galactose and arabinose to either extend or cap the β-1,4 galactan side chains of RGI, respectively. Here we repo...

One of the many functions of reduction-oxidation (redox) cofactors is to mediate electron transfer in biological enzymes catalyzing redox-based chemical transformation reactions. There are numerous examples of enzymes that utilize redox cofactors to form electron transfer relays to connect catalytic sites to external electron donors and acceptors....

Alkaline pretreatment of herbaceous feedstocks such as corn stover prior to mechanical refining and enzymatic saccharification improves downstream sugar yields by removing acetyl moieties from hemicellulose. However, the relationship between transport phenomena and deacetylation kinetics is virtually unknown for such feedstocks and this pretreatmen...

Apiose is a naturally occurring, uncommon branched-chain pentose found in plant cell walls as part of the complex polysaccharide Rhamnogalacturonan II (RG-II). The structural elucidation of the three-dimensional structure of RG-II by nuclear magnetic resonance (NMR) spectroscopy is significantly complicated by the ability of apiose to cross-link vi...

Xylan O-acetyltransferase 1 (XOAT1) is involved in O-acetylating the backbone of hemicellulose xylan. Recent structural analysis of XOAT1 showed two unequal lobes forming a cleft that is predicted to accommodate and position xylan acceptors into proximity with the catalytic triad. Here, we used docking and molecular dynamics simulations to investig...

Rhamnogalacturonan II (RG-II)-the most complex polysaccharide known in nature-exists as a borate cross-linked dimer in the plant primary cell wall. Boric acid facilitates the formation of this cross-link on the apiosyl residues of RG-II's side chain A. Here, we detail the reaction mechanism for the cross-linking process with ab initio calculations...

Two-dimensional (2D) and 3D through-space 13C-13C homonuclear spin-diffusion techniques are powerful solid-state nuclear magnetic resonance (NMR) tools for extracting structural information from 13C-enriched biomolecules, but necessarily long acquisition times restrict their applications. In this work, we explore the broad utility and underutilized...

Chemical reaction kinetics enable predictive scaling studies and process sensitivity analyses that can substantially accelerate commercial deployment of new catalytic transformation technologies. The absence of suitable kinetic parameters for catalytic fast pyrolysis (CFP) of biomass feedstocks has precluded such de-risking simulation activities. I...

Rhamnogalacturonan II (RG-II) is a structurally complex pectic polysaccharide that exists as a borate ester cross-linked dimer in the cell walls of all vascular plants. The glycosyl sequence of RG-II is largely conserved, but there is evidence that galacturonic acid (GalA) methyl etherification and glucuronic acid (GlcA) methyl esterification vary...

Xylans are a major component of plant cell walls. O-Acetyl moieties are the dominant backbone substituents of glucuronoxylan in dicots and play a major role in the polymer-polymer interactions that are crucial for wall architecture and normal plant development. Here, we describe the biochemical, structural, and mechanistic characterization of Arabi...

Applications and associated processing technologies of lignocellulosic biomass are becoming increasingly important as we endeavor to meet societal demand for fuels, chemicals, and materials from renewable resources. Meanwhile, the rapidly expanding availability and capabilities of high-performance computing present an unprecedented opportunity to a...

Acetylation of biomolecules is gaining increased attention due to both the abundance and importance of this modification across all kingdoms of life. Xylans are a major component of plant cell walls and are the third most abundant biopolymer in Nature. O-Acetyl moieties are the dominant backbone substituents of glucuronoxylan in dicots and play a m...

Though common in many industrial chemical processes, multi-step reactions occurring within porous catalyst particles provide significant challenges to previously established modeling frameworks. In this work, a system of reaction-diffusion equations is solved analytically via eigenanalysis. The intraparticle concentration profiles are integrated ov...

Catalytic fast pyrolysis (CFP) is a conversion process that integrates rapid thermochemical depolymerization of solid feedstocks with catalytic transformation to yield small molecules for fuel and chemical products. This process is well‐suited for the conversion of nonfossil feedstocks such as biomass and waste plastics, and thereby holds great pot...

Correction for ‘Unravelling the impact of hydrocarbon structure on the fumarate addition mechanism – a gas-phase ab initio study’ by Vivek S. Bharadwaj et al. , Phys. Chem. Chem. Phys. , 2015, 17 , 4054–4066.

The mechanistic underpinnings of the complex process of plant polysaccharide biosynthesis are poorly understood, largely due to the resistance of glycosyltransferase (GT) enzymes to structural characterization. In Arabidopsis thaliana, a glycosyl transferase family 37 (GT37) fucosyltransferase-1 (AtFUT1) catalyzes the regiospecific transfer of term...

Many studies have suggested that the processing of lignocellulosic biomass could provide a renewable feedstock to supplant much of the current demand on petroleum sources. Currently, alkyl imidazolium-based Ionic Liquids (ILs) have shown considerable promise in the pretreatment, solvation, and hydrolysis of lignocellulosic materials although their...

The recalcitrance of lignocellulosic biomass poses a major challenge that hinders the economical utilization of biomass for the production of biofuel, plastics, and chemicals. Ionic liquids have become a promising solvent that addresses many issues in both the pretreatment process and the hydrolysis of the glycosidic bond for the deconstruction of...

Lignocellulosic biomass is a domestically grown, sustainable, and potentially carbon-neutral feedstock for the production of liquid fuels and other value added chemicals. This underutilized renewable feedstock has the potential to alleviate some of the current socio-economic dependence on foreign petroleum supplies while stimulating rural economies...

Despite the importance of fatty-acid methyl esters (FAMEs) as key components of various green solvents, detergents, plasticizers, and biodiesels, our understanding of these systems at the molecular level is limited. An enhanced molecular-level perspective of FAMEs will enable a detailed analysis of the polymorph and crystallization phenomena that a...

The ability to utilize biomass as a feedstock for liquid fuel and value-added chemicals is dependent on the efficient and economic utilization of lignin, hemicellulose, and cellulose. In current bioreactors, cellulases are used to convert crystalline and amorphous cellulose to smaller oligomers and eventually glucose by means of cellulase enzymes....

A major challenge for the utilization of lignocellulosic feedstocks for liquid fuels and other value added chemicals has been the recalcitrant nature of crystalline cellulose to various hydrolysis techniques. Ionic liquids (ILs) are considered to be a promising solvent for the dissolution and conversion of cellulose to simple sugars, which has the...

The fumarate addition reaction mechanism is central to the anaerobic biodegradation pathway of various hydrocarbons, both aromatic (e.g., toluene, ethyl benzene) and aliphatic (e.g., n-hexane, dodecane). Succinate synthase enzymes, which belong to the glycyl radical enzyme family, are the main facilitators of these biochemical reactions. The overal...

Molecular dynamics simulations using a charge modified general amber force field reveal dimer-based molecular ordering in biodiesel systems that are driven by interactions between ester head-groups. More details can be found in the Full Paper by C. M. Maupin et al. on page 2810 in Issue 13, 2015 (DOI: 10.1002/cphc.201500453).

Abstracts: * Exploring the impact of fuel structure on the anaerobic biodegradation of hydrocarbons.docx (13.0KB) - Uploading Abstracts

Abstracts: * Computational insights into enzymatic free radical chemistry and its role in the bio.pdf (320.4KB) - Uploading Abstracts

α-Conotoxin MII (α-CTxMII) is a 16-residue peptide with the sequence GCCSNPVCHLEHSNLC, containing Cys2-Cys8 and Cys3-Cys16 disulfide bonds. This peptide, isolated from the venom of the marine cone snail Conus magus, is a potent and selective antagonist of neuronal nicotinic acetylcholine receptors (nAChRs). To evaluate the impact of channel-ligand...

Benzylsuccinate Synthase (BSS) is a glycyl radical enzyme that catalyzes one of the most remarkable and energetically challenging reactions in biology- the fumarate addition reaction, which enables microorganisms to utilize hydrocarbons as an energy source under anaerobic conditions. Unfortunately, the extreme sensitivity of the glycyl radical to o...