Inhibition effects of furfural on alcohol dehydrogenase, aldehyde dehydrogenase and pyruvate dehydrogenase

Abstract

The kinetics of furfural inhibition of the enzymes alcohol dehydrogenase (ADH; EC 1.1.1.1), aldehyde dehydrogenase (AlDH; EC 1.2.1.5) and the pyruvate dehydrogenase (PDH) complex were studied in vitro. At a concentration of less than 2mM furfural was found to decrease the activity of both PDH and AlDH by more than 90%, whereas the ADH activity decreased by less than 20% at the same concentration. Furfural inhibition of ADH and AlDH activities could be described well by a competitive inhibition model, whereas the inhibition of PDH was best described as non-competitive. The estimated Km value of AlDH for furfural was found to be about 5μM, which was lower than that for acetaldehyde (10μM). For ADH, however, the estimated Km value for furfural (1.2mM) was higher than that for acetaldehyde (0.4mM). The inhibition of the three enzymes by 5-hydroxymethylfurfural (HMF) was also measured. The inhibition caused by HMF of ADH was very similar to that caused by furfural. However, HMF did not inhibit either AlDH or PDH as severely as furfural. The inhibition effects on the three enzymes could well explain previously reported in vivo effects caused by furfural and HMF on the overall metabolism of Saccharomyces cerevisiae, suggesting a critical role of these enzymes in the observed inhibition.

The effect of Maillard reaction products and yeast strain on the synthesis of key higher alcohols and esters in beer fermentations

“…The synthesis of both higher alcohols and esters are known to be directly affected by these two parameters. Despite research suggesting that MRPs can affect the activity of enzymes involved in the synthesis of higher alcohols (Modig et al, 2002) and antimicrobial properties of MRPs against a number of microorganisms, to date only one study has reported the effect of dark speciality malts on yeast fermentation and volatile metabolite synthesis (Coghe et al, 2005).…”

“…Amongst its many roles magnesium activates cytosolic aldehyde dehydrogenase ALD6, which is involved in the reduction of fusel alcohols to fusel acids, and acts as a cofactor for catalytic phosphoglycerate kinase involved in the formation of pyruvate and ATP (Berg, Tymoczko, & Stryer, 2002). In addition to the more widely studied melanoidins, other MRPs, such as furfural and 5-(hydroxymethyl)furfural (HMF), formed from pentose and hexose degradation respectively, have been shown to have a negative effect on yeast growth, inhibit glycolytic enzymes and induce DNA damage (De la Cueva et al, 2017;Liu et al, 2004;Modig, Lidén, & Taherzadeh, 2002;Palmqvist & HahnHägerdal, 2000) while they have also been shown to inhibit aldehyde and pyruvate dehydrogenases involved in the Ehrlich pathway (Modig et al, 2002).…”

Metabolic engineering of Saccharomyces cerevisiae for improvement in stresses tolerance

“…During acid hydrolysis of lignocellulosic materials, furfural and HMF are generated by dehydration of pentoses and hexoses, respectively, and both furfural and HMF are representative aldehyde inhibitors. 1,2 Aldehydes are toxic to yeasts in inhibition of cell growth [3][4][5] and production of ethanol. 6 Beside aldehydes inhibitors, yeasts need to overcome various stresses during converting sugars to ethanol, such as acid left from pretreatment, high osmotic pressure of hydrolysates, high ethanol concentrations at the last stage of fermentation, high temperature for accelerating fermentation, and process interruptions.…”

INHIBITION OF THE GROWTH OF TOLERANT YEAST Saccharomyces cerevisiae STRAIN I136 BY A MIXTURE OF SYNTHETIC INHIBITORS

“…PI is a fluorescent intercellating agent which cannot cross the membrane of live cells, therefore it is commonly used for differentiating between necrotic and healthy cells (Lecoeur 2002) Herr and Sauer (2008) reported that inhibitors affected cell growth resulting in longer lag phase. Furan furfural inhibits at least three enzymes in the central carbon metabolism (Modig et al 2002). According to Heer and Sauer (2008), furfural concentrations in different lignocellulosic raw materials and hydrolysis processes ranged from 5.5 to 30 mM, leading to the inhibition of …”