Modification of Lactococcus lactis Xaa-Pro dipeptidase based on X-ray crystallographic studies using directed evolution approaches

Dairy fermented products receive a lot of attention from consumers. An issue of dairy fermented foods, especially cheese, is a potential development of bitter taste. A main protein in milk is casein proteins. This family of proteins contains much higher contents of proline, which shows very bitter taste in its peptide forms. During fermentation, casein proteins are hydrolyzed and generate a lot of proline-containing peptides. Because of proline’s unique ring structure, proline-containing peptides are not further hydrolyzed into free amino acids by general proteolysis, but requires proline-specific peptidases. This study aims to study the functionality of a proline-specific peptidase: prolidase. We have studied this enzyme from Lactococcus lactis, a common dairy fermenting bacterium, and found the functionality is unique from other common enzymes, i.e., it shows unique behaviour to the change in the substrate concentrations. This study aims to investigate the functionality of this enzyme and modify the enzyme in order to make it suitable for the debittering process. A key experiment is macromolecular X-ray crystallography in this study, and this internship will give the opportunity to the intern to conduct the research in Canadian Light Source for this experiment.

Faculty Supervisor:

Takuji Tanaka

Student:

Partner:

Canadian Light Source

Discipline:

Life Sciences

Sector:

Agriculture and Food; Biotechnology; Life Sciences (not health)

University:

University of Saskatchewan

Program: