Jose Cerda, Ph.D.

Associate Professor, Director of Chemical Biology
Disciplines Taught: Chemical Biology, Chemistry
Office: Science Center 306
Phone: (610) 660-1787
Fax: (610) 660-1783
Email: jcerda@sju.edu


Dr. Cerda earned a B.S. in Chemical Engineering and a M.S. in Chemistry at the University of Puerto Rico at Mayagüez.   He continued his education at Michigan State University where he received a Ph.D. in Physical Chemistry.  In his graduate research, Dr. Cerda studied the structure of heme proteins by using resonance Raman spectroscopy under the guidance of Dr. Gerald T. Babcock.  As a postdoctoral research associate, Dr. Cerda worked with Dr. P. Leslie Dutton at the University of Pennsylvania where he investigated the properties of redox cofactors by using electrochemical techniques.  He worked on free natural/synthetic cofactors and measured the effects from the surrounding medium (solvent or synthetic protein) on the electrochemical properties of these redox cofactors.  In 2008, Dr. Cerda joined the faculty of Department of Chemistry at Saint Joseph's University.  His current research involves the use of electrochemical methods in the study of redox proteins and redox cofactors.

Education

  • B.S. University of Puerto Rico at Mayagüez 1994 (Chemical Engineering)
  • M.S. University of Puerto Rico at Mayagüez 1997 (Chemistry)
  • Ph.D. Michigan State University 2002 (Physical Chemistry)

Courses Taught

  • CHM 120 General Chemistry I
  • CHM 125 General Chemistry II
  • CHM 120L General Chemistry Lab I
  • CHM 125L General Chemistry  Lab II
  • CHM 320 Physical Chemistry for Chemical Biology
  • CHM 310 Physical Chemistry I
  • CHM 315 Physical Chemistry II
  • CHM 310L Physical Chemistry Lab I

Publications

 

Selected Publications

"Reversible Proton Coupled Electron Transfer in a Peptide-incorporated Naphthoquinone Amino Acid" Bruce R. Lichtenstein,  Jose F. Cerda, Ronald L. Koder, Christopher C. Moser, P. Leslie Dutton. Chemical  Communications 2009, 168-170

"Hydrogen Bond-free Flavin Redox Properties: Managing Flavins in Extreme Aprotic solvents"    Jose F. Cerda, Ronald L. Koder, Bruce R. Lichtenstein, Christopher C.  Moser, Anne F. Miller, P. Leslie Dutton.  Organic & Biomolecular. Chemistry  2008, 6, 2204-2212.

"A Flavin Analogue with Improved Solubility in Organic Solvents" Ronald L. Koder, Bruce R. Lichtenstein, Jose F. Cerda, Anne F. Miller, P. Leslie Dutton. Tetrahedron Letters 2007, 48, 5517-5520.

"Interaction of Nitric Oxide with Prostaglandin Endoperoxide H Synthase-1: Implications for Fe-His Bond Cleavage in Heme Proteins" Johannes P. M. Schelvis, Steve A. Seibold, Jose F. Cerda, R. Michael Garavito, and Gerald T. Babcock.  The Journal of Physical Chemistry B  2000 (104)10844-10850.

"Peroxidase Activity in Prostaglandin Endoperoxide H Synthase-1 Occurs with a Neutral Histidine Proximal Heme Ligand" Steve A. Seibold, Jose F. Cerda, Anne M. Mulichak, Inseok Song, R. Micheal Garavito, Toshiya Arakawa, William L. Smith and Gerald T. Babcock.  Biochemistry 2000 (39) 6616 - 6624.

"Spectroscopic Characterization of the Heme-Binding Sites in Plasmodium faciparum  Histidine-Rich Protein 2" Clara Y. H. Choi, Jose F. Cerda, Hsiu-An Chu, Gerald T. Babcock and Michael A. Marletta.  Biochemistry 1999 (38) 16916-16924.

"Orientation of the Heme Vinyl Groups in the Hydrogen Sulfide-Binding Hemoglobin I from Lucina pectinata" Eilyn Silfa, Maritza Almeida, Jose Cerda, Shaoxiong Wu and Juand Lopez-Garriga.  Biospectroscopy 1998 (4) 311-326.

"Unusual Rocking Freedom of the Heme in the Hydrogen Sulfide-Binding Hemoglobin from Lucina pectinata" Jose F. Cerda-Colon, Eilyn Silfa and Juan Lopez-Garriga.  Journal of the American Chemical Society 1998 (120) 9312-9317.

Research

 

Heme Cofactors

Heme proteins perform a wide variety of cellular functions.  Various proteins utilize the same heme cofactors (iron protoporhyrin IX and derivatives) in the modulation of electron transfer, reduction potential, O2-binding, OO bond scission, and proton translocation.  In some proteins, a clear picture has emerged of the key amino acid residues that are responsible for particular activities.  In many cases, however, quantification of a specific heme-amino acid residue interaction has not been possible due to the difficulty in defining one particular type of interaction in a protein where a matrix of various types of interactions (hydrophobic, pi-pi, and hydrogen bonding) may occur.  Thus, a thermodynamic characterization is necessary to assess the effects of hydrogen bonding to the peripheral substituent groups on a heme and the effects of protonation of these groups. 

A way of quantifying a specific interaction with a peripheral group on the heme is to study model heme compounds in an aprotic solvent, with ligands that can interact specifically with that group.  Aprotic solvents such as dichloromethane and benzene can be used to study hydrogen-bonding interactions between an interacting ligand and a model compound as has been done in previous work. The low dielectric constants of these solvents make them ideal media to study hemes because the interior of proteins have low dielectric constants. The nonpolar and aprotic properties of such solvents facilitate the evaluation of hydrogen bonding and electrostatic interactions between ligands and the peripheral groups of hemes.  Small heme-ligand interactions, perhaps too small to be measured in commonly-used solvents, can be magnified in benzene and dichloromethane.

UV/Vis Spectroelectrochemical Studies

A technique that is frequently used in our lab is UV/Vis spectroelectrochemistry.  Our setup is shown below. The method is useful in the study of synthetic and natural redox proteins. 

The electrochemical cell is composed of three electrodes, a pair of gold slides (working), a platinum wire, and a reference electrode.  The reference is a Ag-AgCI electrode. The in-house electrochemical cell is sealed and argon gas is used to maintain an anaerobic environment during the measurements.  An electrochemical station is used to change the applied potential.

The UV/Vis spectral property of a redox cofactor is related to its electronic state.  A change in the spectrum generally occurs when the sample is subjected to a change in its redox state.  The combination of electrochemistry with UV/Vis spectroscopy is useful for obtaining the midpoint potential of a protein (as shown below).

 

UV/Vis spectroelectrochemistry of myoglobin (Mb) in the presence of fluoride

The oxidized spectrum of Mb in the presence of fluoride shows absorptions at 607 nm and 409 nm.  As the applied potential is changed, the protein starts to reduce to form the ferrous deoxy Mb.  The ferrous heme is characterized by absorptions at 557 nm and 434 nm.  A plot of the absorbance at 434 nm versus the applied potential can be used to obtain the midpoint potential of the protein (right side).


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