AbstractsBiology & Animal Science

According to official reports, cardiovascular disease and cancer are major causes of death in many countries. Cardiovascular disease is closely related with high cholesterol level, therefore, inactivation of enzymes involved in cholesterol biosynthesis is one major method for treating cardiovascular disease. Mevalonate pathway is a main pathway responsible for cholesterol biosynthesis, which include 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, mevalonate kinase (MVK), phosphomevalonate kinase (PMK), mevalonate 5-diphosphate decarboxylase (MDD), farnesyl pyrophosphate synthase (FPPS) and several other enzymes. The mevalonate pathway is a drug target for chemotherapy of cardiovascular disease at present, and is a promising target for the development of anticancer and antimicrobial agents. Because it is difficult to inhibit an enzyme completely (particularly with a reversible inhibitor), inhibition of two consecutive enzymes in a pathway using a combined drug treatment can block the pathway much more effectively than a single inhibitory drug therapy. Therefore, drug combination has been used in clinical treatment of various diseases, and sequential blocking of two enzymes in a metabolic or biosynthetic pathway is one strategy for enhancing treatment. In this thesis, our work is mainly composed of three parts. The first part is the expression and purification of three enzymes, which are all ATP-dependent, in the mevalonate pathway: MVK, PMK and MDD. These enzymes are all related with the regulation of cholesterol biosynthesis in cells and may be promising targets for controlling the downstream product biosynthesis in the mevalonate pathway. The second part is syntheses of bifunctional or multifunctional enzyme inhibitors for the enzymes listed above. We developed new type of inhibitors by adding the naturally existing amino acid and geranyl group as the functional groups into the biphosphate. It is possible that there are strong interactions between the amino acids in the inhibitors and the enzymes. Geranyl pyrophosphate has been reported as feed back inhibitor of mevalonate pathway. The last part is the activity tests of the inhibitors for the three enzymes. The results indicate that several inhibitors show strong inhibition activities and may be useful compounds for further development for treating cardiovascular disease and cancer. Some of the inhibitors show inhibition of more than one enzyme, and this type of molecules offer us a new example of a single inhibitor blocking two sequential steps simultaneously in the mevalonate pathway. In conclusion, this thesis describes the development of multifunctional inhibitors in the mevalonate pathway. A series of inhibitors were synthesized and characterized, and some of them were found to be multifunctional enzyme inhibitors in mevalonate pathway. This study provides us useful information for the development of new drugs for the treatment of cardiovascular disease and cancer. xvii, 139 p. : ill. (some col.) 30 cm. CityU Call Number: QP601 .G96…