A protein's function is dependent on its structure, which is made up of amino acids. Proline, (an amino acid) is known to cause the kinks and turns in protein structures. However, little is known about the influence of pH on the isomeric preference of proline-attached dipeptides. For this experiment, the isomeric preference of methionine-proline was measured in 10% solutions for pH levels of 7 and 11, the pH of the human body falls between the range of 6 and 9. At pH 11, NMR-90 spectra showed that the cis- isometric form was preferred at a rate of 14% more than the trans- isometric form, measured by the alpha hydrogen. At neutral pH of 7 trans- isomers are preferred 36% more than the cis- form measured by the alpha hydrogen and 73% more measured by the delta hydrogen. In conclusion, this experiment supports the hypothesis that proline-attached dipeptides’ isomerization is pH dependent and is more likely to be in cis- form when in high pH in comparison to a neutral pH. The purpose of this experiment is to determine if pH levels can change the structure of a protien, with further research exploring if the change of structure changes the function. This is important to determine if medications containing amino acids can have an optimal or range of pH.