Early work Linderstrøm-Lang began as a physicist. Only a year after the publication of the
Debye–Hückel theory, Linderstrøm-Lang applied it to proteins and contributed in defining the term
isoionic point. In particular, he formally considered the
ensemble of protonation states. Linderstrøm-Lang began in the Carlsberg laboratory under its second director
S. P. L. Sørensen (who invented the
pH scale). 1949 volumetric studies showing that the interior of proteins has very few charges and, hence, is likely to be hydrophobic.
Innovative methods Perhaps the most elegant method developed by Linderstrøm-Lang is the Cartesian diver for measuring density. A long tube containing oils of gradually increasing density was prepared. A droplet containing a protein mixture is introduced and falls until it reaches its density. Very small changes in the density of the droplet (e.g., those due to an ongoing enzymatic reaction) could be observed by movements of the droplet in the
density gradient.
Hydrogen-deuterium exchange Kaj Ulrik Linderstrøm-Lang is considered the father of
hydrogen–deuterium exchange for protein analysis.
Contributions to protein structure and stability Linderstrøm-Lang is justly famous for his organization of protein structure into four levels:
primary,
secondary,
tertiary and
quaternary structure. He did so in his Lane Medical Lectures, which were delivered at
Stanford University on 2, 4, 8, 10 and 12 October 1951, and later published by Stanford University Press.
Contributions to other scientists Linderstrøm-Lang contributed to the training of a whole generation of protein scientists, such as
Frederic M. Richards, H. A. Scheraga,
Christian B. Anfinsen, William F. Harrington, etc. He is also credited with the insight that the free energy of hydrophobic interactions does not depend only on energy (but also entropy), from his realization that mixing water and alcohol (which contains a hydrophobic methyl group) gives off heat. ==Awards and honors==