Abstract
The aim of this study is to acquire better knowledge of the action of the whole smoke and the vapour phase on alcohol dehydrogenase (ADH), lactic dehydrogenase (LDH), and malate dehydrogenase (MDH). The method developed provides that smoke comes into direct contact with the various enzymatic solutions without any preventive extraction, as in previous methods. It is based on the determination of the degree of inhibition of sulfhydryl reagent groups of enzyme by smoke. Additionally, the efficiency of cigarette filters for the reduction of this inhibition was evaluated. The purpose of this study also included the examination of the protective effect of thiol groups of enzymes against the inhibitory action of smoke. The results obtained show a high reactivity of smoke with sulfhydrylic groups of the enzymes examined. The effect of this reactivity is different for the three enzymes considered and dependent upon the role that sulfhydryl reagent groups had in the enzymatic activity. In particular, it was found that alcohol dehydrogenase, which needs all its sulfhydryl groups for its own activity, undergoes a strong inhibition due to smoke, while lactic dehydrogenase shows a negligible inhibition. The tests made have also shown the protective action of thiol on the inhibited enzymes.