Class: BE210
Group: W6
Members: FACILITATOR PRASHANTH JAYARAM, TIME & TASK KEEPER CHUNGPENG SHEN,SCRIBE TONY YEUNG, PRESENTER GREG MILLER
Date: 5/11/00
Full Text

Abstract:

The relationship between nonpolar side chain length of amino acids and their heats of combustion was determined by combusting glycine, valine, and leucine in the Parr1341 Oxygen Bomb Calorimeter. The heats of combustion of the aforementioned amino acids were found to be 233.21kcal/mol ? 0.93%CL, 684.25 kcal/mol ? 1.59%CL, and 846.57 kcal/mol ? 1.56%CL, respectively. Their percentage standard deviations were found to be ?0.75%, ?1.28%, and ?1.36%, respectively. The heats of combustion of glycine, valine, and leucine only deviated from their respective literature values by 0.17%, -1.64%, and -0.78%. The relationship between the side chain and the heats of combustion of nonpolar amino acids was determined to be linear.  It was found that the HC of nonpolar amino acid with linear side chain composed of only CH, methyl and methylene groups is equal to 231.83 kcal/mol ? 3.75% CL plus the product of 152.65 kcal/mol ?1.98% CL and total number of CH, methyl and methylene group(s).  The aforementioned relationship was very consistent with the slope and the intercept of the line from literature values with % deviation of  -0.262% and -1.47% respectively. Furthermore, the 95% confidence limits were ? 3.75% and ? 1.98%; indicating a high level of confidence of the experimental values of the slope and intercept.  However, the above relationship should only be applied to nonpolar amino acids with fairly linear side chains consisting of methyl and methylene groups. Using the experimental linear relationship between HC and the length of side chain, HC of nonpolar amino acids with nonlinear structure, double bonds, nitrogen, and sulfur in the side chains could depart from their literature values by as much as 19.4%.