SPECTROSCOPIC INVESTIGATION OF STRUCTURE AND DYNAMICS OF THIAMINE KINASE IN PIG BRAIN TISSUE

Steady-state fluorimetry was used to study the effects of substrates (thiamine, Mg?АТР), cofactors (Mg2+, Mn2+, Ca2+) and effectors (thiamine phosphate esters, pyruvate, phosphoenol pyruvate, ethyl pyruvate) on the structure and dynamics of thiamine kinase (EC 2.7.6.2) in pig brain tissue. Binding of the ligands to thiamine kinase was shown to be accompanied by quenching of its tryptophane fluorescence. The analysis of the results obtained revealed that thiamine and ATP were bound by the pyrimidine and adenide rings at the hydrophobic region of the enzyme's molecule. Pyruvate has two binding sites: an inhibitory (relatively hydrophobic) and an activating hydrophilic site, the latter being in a close proximity to the thiamine's binding centre and providing the interaction between the carbonyl group and the substrate. Divalent metal ions raised affinity of the substrates and effectors for thiamine kinase, favouring simultaneously in inсrease in hydrophobicity of its active site.