UCR

Center for Plant Cell Biology



Members


Cynthia LariveCynthia Larive

Professor; CNAS Divisional Dean, Chemistry, Math, and Physics & Astronomy

Mailing Address:

Chemistry
Chemical Sciences /328
University of California
Riverside, CA 92521

Phone: (951) 827-2990
Fax: (951) 827-4713
Email: clarive@ucr.edu

Website

Degree(s):

PhD 1992 University of California, Riverside
MS 1982 Purdue University
BS 1980 South Dakota State University

Center/Inst Affiliation(s):

Center for Plant Cell Biology

Areas Of Expertise:

Bioanalytical Chemistry, including NMR, Electrophoretic Separations, and LC-MS/MS; Metabonomics Studies Related to Chemical Biology and Hypoxia in Plants, and Oxidative Stress in Rats; Development of New Methods for Analysis of Heparin/Heparan Sulfate and Studying their Biochemistry; Development of New NMR Methods for the Analysis of Protein-ligand Interactions

Awards / Honors:

2008  AAAS Fellow (American Association for the Advancement of Science)
2007  J. Calvin Giddings Award for Excellence in Education, ACS Division of Analytical Chemistry
2005  Honoris Causa Doctorate, Semmelweis University, Budapest, Hungary
2004-present  IUPAC Fellow
2002  Award for Teaching Excellence (selected by Chemistry undergraduate students)
2001  IUPAC Young Observer
1996  Eli Lilly New Faculty Award
1995  National Science Foundation CAREER Award

Research Summary:

Using Metbonomics to Probe Biochemistry and Physiology.

Metabonomics is a systematic approach to identifying changes in the relative levels of endogenous metabolites in an organism in response to a stress or perturbation, be it genetic mutation, disease, or exposure to a chemical or toxic substance. Graduate students Christiana Merrywell and Kayla Hamersky, supported by the UCR Chemical Genomics NSF IGERT program, and are collaborating with UCR faculty Natasha Raikhel and Julia-Bailey Serres to use metabonomics to investigate aspects of plant biochemistry. Christiana Merrywell is working with the Raikhel group to understand the metabolic effects of the Sortins (sorting inhibitors isolated from a chemical genomics screen). Kayla Hamersky collaborates with the Serres group to evaluate the metabolic effects of hypoxia.  Our group uses analytical techniques that produce data sets with high information content like NMR spectroscopy and LC-MS/MS to analyze changes in the levels of endogenous metabolites in plant extracts. The resulting datasets subjected to univariate and mutivariate analyses, such as principal components analysis (PCA).

600 MHz 1H NMR spectra of extracts from several different organisms

As shown in this figure, 1H NMR spectra can be used for metabolic fingerprinting, providing an overview of similarities/differences in metabolism of different organisms, wild-type and mutant strains of the same organism, or between control and treated organisms. While some differences can be determined simply by inspection of these spectra, a quantitative analysis is required to mine the maximum information from the datasets. While levels of individual metabolites can be examined via standard procedures for means and significance testing (i.e. the Student’s t test), PCA is an unsupervised multivariate data reduction routine that reveals inherent grouping in the data observed through linear combinations of the variables. As shown below for PCA analysis of 1H NMR spectra acquired for pooled human, bovine and rat urine samples, separates the samples into groups while the loadings plot reveals the 1H NMR chemical shift regions most responsible for the variance in the data.


Development of NMR Microcoil Probes and their Application to Heparin Analysis.
 

Scores and Loadings plots produced by principal components analysis of 1H NMR spectra measured for pooled human, bovine, and rat urine samples

Heparin is an important drug with a $3.7 billion market world-wide in 2005. In addition to its anticoagulant properties, heparin and the related glycoseaminoglycan heparan sulfate (HS), bind to hundreds of proteins important in cell development, the immune response and cancer. The structural complexity and microheterogeneity of heparin and HS make their characterization a challenging task. As shown here, heparin microheterogeneity is introduced by enzymatic remodeling reactions that occur as the biopolymer is biosynthesized.  Upon chain elongation, the disaccharide units undergo a stepwise series of modifications that include N- and O-sulfation and epimerization. An impediment to the elucidation of the structure and biological function of these polysaccharides is the lack of sufficiently sensitive and specific analytical techniques. Isolation and purification of the milligram quantities of heparin-derived oligosaccharides currently required for characterization by NMR is a tedious and time consuming process.

Examples of the enzymatic remodeling processes that are responsible for heparin’s microheterogeneity.

Our research group is working to improve the analytical methods used for heparin analysis. For example we have recently developed a 5 minute LC-MS method that resolves and quantifies heparin disaccharides directly from the enzymatic digest. A major focus of our research is the development of microcoil NMR technology and its use to advance the analysis of materials available in limited amounts, for example heparin oligosaccharides produced by enzymatic or chemical digestion. Our research aims to improve the sensitivity of NMR detection through measurements in 25 nanoliter detection volumes, 20,000 times less than required by standard NMR equipment. Microcoil NMR detection is coupled with capillary isotachophoresis (cITP), an electrophoretic separation method that can concentrate charged analytes by 2 to 3 orders of magnitude.  These improvements in sensitivity allow the use of cITP-NMR for acquisition of survey spectra facilitating analysis of microgram quantities of heparin-derived oligosaccharides, such as the disaccharide shown here.

Combined with LC-MS, capillary electrophoresis, and 2D NMR measurements in a commercial microcoil probe, we have developed a unified approach for separation and analysis of small quantities of di- and higher oligosaccharides. This allows us to efficiently examine the relationships between heparin and HS microstructure and the biological processes they control. A particular interest of our group is the role of these glycosaminoglycans in Alzheimer’s disease and in development, for example in stem cell differentiation. 

Understanding Ligand – Protein Interactions
Specific ligand-protein interactions are integral to the ability of proteins to carry out processes vital for human life such as enzymatic transformations, receptor and antibody recognition, and signal transduction. Therefore the study of ligand-protein interactions is important for understanding the biochemical basis of many diseases and provides an opportunity for the development of pharmaceutical compounds with agonistic or inhibitory activity.

NMR is a useful analytical tool for the study of ligand-protein binding, because changes can be detected when a small ligand interacts with a macromolecular target without the need for special labels. We have developed NMR diffusion experiments that provide improved spectral selectivity in ligand binding studies by manipulation of NMR pulse sequences to reduce the protein background or enhance specificity in cases where several ligands are studied simultaneously. The build-up of transferred-NOEs during the diffusion experiment, measured as differential degrees of curvature in the “linearized” diffusion plot (as shown below for tryptophan binding to human serum albumin. This information about the communication between the protein and ligand protons can provide insight into the nature of ligand-protein binding and can be used to prepare an epitope map of the ligand which is useful for the elucidation of structure activity relationships. The results from NMR diffusion experiments are combined with those obtained by saturation transfer difference (STD) and T1ρ filtered NOESY to obtain a more complete picture of the ligand binding epitope. 
 
Diffusion NMR plot showing differential effects resulting from binding to human serum albumin.

Spring 2007 photo of the Larive Research Group

 

Back row from left: John Limtiaco, Cynthia Larive, Albert Korir, Patrick Brown, James Kim, Stacie Eldridge, Kasie Fang.
Front row from left: Jennifer Cruz, Kayla Hamersky, Fernando Campos, Christiana Merrywell.

Selected Publications:

List of publications from HubMed

Lab Personnel:

Barding, Greg
Graduate Student Researcher —
Bulloch, Daryl
Graduate Student Researcher —
Cruz, Jennifer
Graduate Student Researcher —
Jones, Christopher
Graduate Student Researcher —
Kaiser, Kayla
Graduate Student Researcher —
Langeslay, Derek
Graduate Student Researcher —
Limtiaco, John
Graduate Student Researcher —
Orr, Daniel
Graduate Student Researcher —
 

More Information

General Campus Information

University of California, Riverside
900 University Ave.
Riverside, CA 92521
Tel: (951) 827-1012

Career OpportunitiesUCR Libraries
Campus StatusDirections to UCR

Center Information

Center for Plant Cell Biology
Botany & Plant Sciences Department
2150 Batchelor Hall

Tel: (951) 827-7177
Fax: (951) 827-5155
E-mail: genomics@ucr.edu

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