Naslov
The Molecular Mechanism of the Temperature Enhancement of Proton Magnetic Relaxation Rates in Methaemoprotein Solutions

Autori
Vuk-Pavlović, Stanimir ; Benko, Bojan ; Maričić, Siniša

Izvornik
Biophysical chemistry (0301-4622) 2 (1974), 4;

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Haemoglobin; Myoglobin; Haemoprotein; Proton magnetic relaxation; Stereochemical probe

Sažetak
The mechanism of water exchange between the haem-pocket and bulk solvent in aqueous methaemoprotein solutions was firmly substantiated by using the aliphatic protons of certain lower alcohols in an otherwise deuterated solution for measuring the incremental relaxation rates resulting from their magnetic interactions with the haem-iron. The fast exchange condition was established for solutions of horse fluorometmyoglobin, human A fluoromethaemoglobin and Chironomus thumi aquomethaemoglobin. The distances between the exchangeable protons and the haem-iron obtained from these PMR measurements concur with the presence of the fluoride ion, while for Chironomus aquomethaemoglobin this distance is also much larger than that resulting from the location of the 6th site water molecule. The latter finding id the first clear-cut evidence that the exchanging protons belong to the next neighbour water molecule, a previously advanced hypothesis. The exchanging water molecules may thus serve as a natural probe for comparing the haem-pocket conformational state(s) under different conditions or in various haemoproteins

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemija, Biologija

POVEZANOST RADA