POLYMERASE CHAIN-REACTION IN LIPOSOMES

Background: Compartmentalization of biochemical reactions within a sph erically closed bilayer is an important step in the molecular evolutio n of cells. Liposomes are the most suitable structures to model this k ind of chemistry. We have used the polymerase chain reaction (PCR) to demonstrate that complex biochemical reactions such as DNA replication can be carried out inside these compartments. Results: We describe th e first example of DNA amplification by the PCR occurring inside lipos omes composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POP C), or of a mixture of POPC and phosphatidylserine. We show that these liposomes are stable even under the high temperature conditions used for PCR. Although only a very small fraction of liposomes contains all eight different reagents together, a significant amount of DNA is pro duced which can be observed by polyacrylamide gel electrophoresis. Con clusions: This work shows that it is possible to carry out complex bio chemical reactions within liposomes, which may be germane to the quest ion of the origin of living cells. We have established the parameters and conditions that are critical for carrying out this complex reactio n within the liposome compartment.