K.O. Greulich



With the advent of single molecule technique biochemical analysis has reached its ultimate sensitvity. We have studied the reaction of Lactate dehydrogenase (LDH) , a molecule used in the diagnosis of heart infarction, and the sequence specific cutting of (Lambda phage -) DNA by restriction endonucleases.
Single DNA molecule restriction in principle allows single molecule DNA typing. A number of review articles from the group is available
K.O.Greulich 2004 CurrPharmBiotech 5  243 - 259
K.O.Greulich 2005 ChemPhysChem  6  2459 - 2477
Presently a special issue of INT J MOL SCI is being edited by KOG together with H. Schneckenburger Ulm / Aalen:


Major results are

i) The conversion of Fumarate into Lactate by LDH 1 can be observed on a single molecule basis. Michaelis constants determined by single molecule reactions are essentially the same as when they are determined in bulk,  i. e. in this respect the ergodic theorem is satisfied.

ii) Single molecule restriction of single molecules is possible. The length of fragments determined by single molecule restrictions are accurate within  + / - 15 %.  Fragments with similar lengths, which in a bulk technique run in one overlapping band on the electrophoresis gel, can be easily distinguished.

iii) Restriction endonucleases primarily remain on their target DNA molecule and perform all cuts. They move by linear diffusion.There is no jumping or hopping.


Background information - movies on single molecule reactions

Single Molecule Enzyme Kinetics

Single Molecule DNA Handling and Restriction Analysis