Esterases of Baker's Yeast. Ii. Substrate Specificities Towards Esters Formed During Sugar Fermentations

Abstract

Ethyl esters of fatty acids (C,-C,,), isoamyl acetate and 2-phenethyl acetate were studied as sub strates for yeast esterases and compared with the synthetic substrates, p-nitrophenyl esters and P-naphthyl esters. Intact yeast, the 55% and 55-75% ammonium sulphate precipitate of centrifuged yeast homogenate, and partly purified esterases were used for the determination of the hydrolysation activity towards the esters.The results showed that the yeast esterases prefer to hydrolyse the ethyl esters with acyl chain length of Cs to C,,. The acetate esters, ethyl acetate, isoamyl acetate and 2-phenethyl acetate are only very slowly hydrolysed or remain unaffected. The substrate specificity of different esterases varies and can be used for their characterisation.Investigating pH optimum curves using intact yeast and a crude esterase preparation and different substrates confirmed the earlier result that there are esterases on both sides of the plasma mem brane. The specificity of intracellular and periplasmically located esterases is, however, different.

Solubilization and Activity Detection in Polyacrylamide Gels of a Membrane-Bound Esterase from an Oenological Strain of Saccharomyces cerevisiae

“…The highest catalytic activity was found with β-naphthyl acetate, whereas no hydrolytic activity was detectable with esters of fatty acids longer than C14 (data not shown), confirming previously reported results 19 . The sub-cellular localization of the enzyme/s with esterase activity was then investigated and a method for their visualization on electrophoretic gels was developed.…”

“…From this point of view, the characterization of the different yeast esterases is of primary importance and the methods described here for the fractionation and visualization on gels of these enzymes contribute to a better understanding of their action. However, the esters used in this study are rather unspecific substrates for several forms of esterases and it must be stressed that the affinity of the various esterases for a given substrate can be very different 19 . Therefore, in order to elucidate the effects of these enzymes on ester levels, it will be necessary to test their activities on those substrates that are actually found in wine.…”

Expression Levels of the Yeast Alcohol Acetyltransferase GenesATF1,Lg-ATF1, andATF2Control the Formation of a Broad Range of Volatile Esters

“…As esterases are responsible for the breakdown of esters, it is clear that their activity may affect the concentration of certain volatile esters. In S. cerevisiae, for example, it has been shown that the balance between ester-synthesizing enzymes and esterases, such as Iah1p (also known as Est2p), is important for the net rate of ester accumulation (27)(28)(29)(30) (59,60,61,62,70). This indicates that esterases may also play a role in the formation of certain esters (42,62,70).…”

A novel esterase fromSaccharomyces carlsbergensis, a possible function for the yeastTIP1 gene

“…The esterase found in the present study has a broad substrate preference towards esters of p-nitrophenol, but only hydrolyses the long-chain esters, ethyl hexanoate and ethyl octanoate in beer. A broad substrate specificity was also observed for the cell wall esterases and intracellular esterases (Schermers et al, 1976;Parkkinen and Suomalainen, 1982). The esterase described here is relatively resistant to heat; after pasteurization, where heating at 60 C for 20 min is performed, a low level of esterase activity was still present.…”