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I. G. Panyutin studied the physical chemistry of DNA strand exchange. In 1994, work with P. Hsieh measured spontaneous branch migration, the motion of an exchange junction along homologous double-stranded DNA.^[ref]

The experiments varied temperature and ions while using defined DNA substrates. Removing magnesium accelerated the reported process by roughly a thousandfold. The comparison illustrates why an observed reaction rate is not a property of the DNA sequence alone: solution conditions can alter junction geometry and therefore how readily exchange proceeds.^[ref]

P. Hsieh investigated DNA reactions involved in genetic recombination. A 1994 study with I. G. Panyutin isolated spontaneous branch migration of a Holliday junction for kinetic measurement.^[ref]

Complementary single-stranded ends joined two double-stranded DNA substrates into a four-stranded junction. Movement to the far end produced strand-exchanged products. Measuring that conversion under different solution conditions showed that the surrounding ions, especially magnesium, strongly changed the rate. This separated a physical DNA reaction from the additional regulation supplied by cellular proteins.^[ref]

By I. G. Panyutin and P. Hsieh. Proceedings of the National Academy of Sciences 91(6),2021–2025(15 March1994). DOI doi.org/10.1073/pnas.91.6.2021

Abstract: complementary-tailed duplex substrates form a four-stranded junction; complete spontaneous migration gives strand-exchanged products. Kinetics vary with temperature and ionic conditions; magnesium strongly slows migration.