Class: BE210
Group: W5
Members: FACILITATOR
.
..George
Liao
TIME & TASK KEEPER
.
...Lisa Toppin
SCRIBE
.
..Michael Jue
PRESENTER . . Erica So
Date: May, 2001
Abstract:
The objective of this experiment was to develop a titration and calculation
protocol to find the basic pKa values of arginine. Three methods were developed
to calculate the pKa values of arginine: a linear regression method, an
intercept method and a derivative method. The regression method calculated
pKa2 to be 9.136 +/- 0.079, pKa3 to be 12.190 +/- 0.618 and pI to be 10.663
+/- 0.348. The intercept method calculated pKa2 to be 9.183.
The derivative method calculated pKa2 to be 9.053 +/- 0.026, pKa3 to be
12.32 +/- 0.093 and pI to be 10.686 +/- 0.060. These values are within
the 95% confidence intervals of the literature values. The accuracy of
the experiment was pre-established to be within 3% and all of the experimental
values fell within this uncertainty. The precision of these results demonstrates
that the results obtained in the experiments are reproducible. The lack
of overlap of the two basic pKa values indicates that distinct values for
the pKa values were obtained. It has been concluded that the titration
protocols and the mathematical model developed in this project are applicable
to accurately determining the basic pKa values of the amino acid Arginine,
and could be used to find the pKa values for other species with more than
one pKa value in either the basic or the acidic region.