purcc 2012 - University of the Pacific

Poster Session Abstracts
Some of these compounds are so complex that
measurements for acidity and basicity cannot be
carried out experimentally. For this reason,
molecular modeling calculations are used to
determine the theoretical value. Spartan and
Gaussian were the computational programs that
were used to determine the three dimensional
structure of the organic compounds. From there,
various calculations were carried out to
determine the acidity and basicity. The
theoretical values were compared with
experimental data for known compounds to
evaluate the method. The results showed that the
theoretical values directly correlated with the
experimental data.
Synthesis of Polypeptides and Cleavage
Rajneet Padda
Faculty Mentor: Jianhua Ren
Polypeptides are short polymers that contain
amino acid residues and are linked by a
peptide bond. The peptide bonds correlate with
the secondary structure of proteins, which are
either alpha helices or Beta sheets. Changing
an amino acid residue in a primary structure
can change the way a protein folds; therefore,
affecting the function of the protein. In order
to understand how the primary structure can
affect the protein folding, it is extremely
important to understand the chemical
properties of polypeptides
In this research various peptides are
synthesized using the Solid Phase Peptide
Synthesis. In this procedure amino acids are
attached to Rink Amide resins one at a time
until the peptide of choice is synthesized. Then
the peptide is cleaved from the resins using a
cleavage reagent. In order to obtain a peptide
with high yield and high purity, the right
cleavage reagent must be used. For Cys-Ala-
Ala-Ala and Ala-Ala-Ala-Cys peptides, three
cleavage reagents have been tested in our lab:
TFA and Reagent R, and Reagent B. The
results from the three cleavage reagents will be
presented in the poster.
Expression and gene modification of Taqpolymerase
using the SUMO purification
system
Juan Manuel Abundes, Elaina Khoo, Lifang
Zhou, Jennifer Ou, Felicia Resendez,
Hyungsuk Lee, Christina Quach
Faculty Mentor: Jerry Tsai
Taq DNA polymerase is an enzyme produced by
the thermophilic bacterium Thermus aquaticus,
which is commonly used to amplify DNA in the
polymerase chain reaction (PCR). The enzyme’s
unique ability to withstand high temperatures,
36-75°C, makes it an efficient enzyme for cycles
of heating and cooling. Purification of Taq
polymerase can be done through heat lysis.
While this is adequate for general use, this
method produced an impure Taq polymerase
mixed with other contaminating proteins. The
impurities make it difficult to only study Taq
polymers. With this in mind, an improved
purification method was employed that
combined the affinity tag of histidines along with
the small ubiquitin-related modifier (SUMO)
gene. This histidine tag of the SUMO system is
an ideal purification technique for Taq
polymerase due to the tag’s affinity to nickel. It
was proposed that cloning the Taq gene into the
SUMO expression system would facilitate easy
purification. SUMO modulates protein structure
and function by binding to the lysine side chains
of target proteins. The Taq polymerase gene is
cloned onto the C-terminal end of the SUMO
gene using a PCR approach. Specific DNA
primers were designed to introduce the excised
Taq gene into the proper vector. Then, by
inducing the bacterium, Escherichia coli (E. coli)
with this gene, the Sumo-Taq protein can be
expressed, to later be isolated using affinity
chromatography involving the Nickel resin. Taq
polymerase alone can be isolated by flowing
SUMO protease through the column, resulting in
simple and homogenous purification of this
protein.
Adventures in New Metal Complexes
Design and Synthesis
Una Lee, Sirena Lau, Vickie Nguyen,
Sarah Chiu
Faculty Mentor: Qinliang Zhao
Yi-Ju Tsai (graduate student)
Functionalization of an organic molecule often
involves C-H bond activation. However, the
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