Hydroxyl protons can become helpful elements to study conformation, solvation and hydrogen bonding in carbohydrates. They can be observed working in DMSO, water-acetone ( 91JACS363 ) or in supercooled water-D2O mixture ( 94NAT1 ) at -5/-20 degree. Recently, binary mixtures of water-aprotic solvents have been analysed to turn hydroxyl protons into conformational sensors in biomolecular complexes ( 03JB197-25 ).

Several works have been reported analyzing the following NMR data ( 92JB109 , 98PERK2385 , 98PERK809 , 00CRE409 , 00PERK2147 , 01CRE319 , and 02EJOC1925 ):

Chemical shift of hydroxy protons involved in hydrogen bonds tend to be deshielded. They usually appear in the 5.4-6.5 ppm region. ( 81MRC28 and 94MRC225 )

¹H-¹H coupling constants of the order of 5-6 Hz indicate a free rotation of the hydroxyl group around the C-O bond. Large values around 8-9 Hz indicate relatively restricted rotation due to an anti conformation. This restriction is usual in hydrogen bonded systems. ( 81MRC28 and 94MRC225 )

¹H-¹³C coupling constants ( 99CRE267 )

Temperature coefficients on chemical shifts.

Deuterium isotope effects on ¹³C chemical shifts ( 84JACS6180 and 85JACS1747 ). The SIMPLE method ( 85MRC582 , 87PERK97 and 87PERK97 ). Other isotope Effects ( 98JB161-12 )

Inter- and intra-residue NOEs using NOESY and ROESY esperiments that laso are used to discriminate between cross-relaxation and chemical exchange contributions.

Exchange rates . Protons involved in strong hydrogen bonds exhange more slowly with the solvent

In addition, they can be used for structural elements using conventional or specific NMR experiments ( 97JB47 ).