Effect of Ethanol on Mucus Glycoprotein Fatty Acyltransferase from Gastric Mucosaα

Bronislaw L. Slomiany, Yun H. Liau, Andrzej Piasek, Amalia Slomiany

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The enzyme activity that catalyzes the transfer of palmitic acid from palmitoyl coenzyme A to the deacylated intact or deglycosylated gastric mucus glycoprotein was demonstrated in the detergent extracts of the microsomal fraction of antral and body mucosa of the rat stomach. Both types of mucosa exhibited similar acyltransferase activities and acceptor specificities. A 10-14% decrease in the fatty acyltransferase activity was observed with the reduced and S-carboxymethylated mucus glycoprotein, but the proteolytically degraded glycoprotein showed no acceptor capacity. This indicated that the acylation of mucus glycoprotein with fatty acids occurs at its nonglycosylated polypeptide regions and that some of the fatty acids may be linked via thiol esters. Optimum enzyme activity was obtained at pH 7.4 with the detergent Triton X-100, NaF, and dithiothreitol. The apparent Km values for the intact and deglycosylated mucus glycoproteins were 0.45 and 0.89 μM, respectively. The acyltransferase activity of the microsomal enzyme was inhibited by ethanol. With both intact and deglycosylated glycoprotein substrates, the rate of inhibition was proportional to the ethanol concentration up to 0.4 M and was of the competitive type. The K1 values were 0.80 μM for the intact mucus glycoprotein and 1.82 for the deglycosylated glycoprotein. Preincubation of the microsomal enzyme with low concentrations of ethanol (up to 0.5 M) did not seem to exert any additional deterrent effect on acyltransferase activity. Higher concentrations of ethanol (1.0 M and above), however, caused substantial reduction in the transferase activity due to denaturation of the enzyme.

Original languageEnglish (US)
Pages (from-to)3514-3521
Number of pages8
JournalBiochemistry
Volume24
Issue number14
DOIs
StatePublished - Jul 1 1985

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Acyltransferases
Gastric Mucosa
Ethanol
Enzymes
Glycoproteins
Enzyme activity
Detergents
Mucous Membrane
Fatty Acids
Palmitoyl Coenzyme A
Acylation
Denaturation
Palmitic Acid
Dithiothreitol
Octoxynol
Transferases
Sulfhydryl Compounds
Rats
Stomach
Esters

All Science Journal Classification (ASJC) codes

  • Biochemistry

Cite this

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title = "Effect of Ethanol on Mucus Glycoprotein Fatty Acyltransferase from Gastric Mucosaα",
abstract = "The enzyme activity that catalyzes the transfer of palmitic acid from palmitoyl coenzyme A to the deacylated intact or deglycosylated gastric mucus glycoprotein was demonstrated in the detergent extracts of the microsomal fraction of antral and body mucosa of the rat stomach. Both types of mucosa exhibited similar acyltransferase activities and acceptor specificities. A 10-14{\%} decrease in the fatty acyltransferase activity was observed with the reduced and S-carboxymethylated mucus glycoprotein, but the proteolytically degraded glycoprotein showed no acceptor capacity. This indicated that the acylation of mucus glycoprotein with fatty acids occurs at its nonglycosylated polypeptide regions and that some of the fatty acids may be linked via thiol esters. Optimum enzyme activity was obtained at pH 7.4 with the detergent Triton X-100, NaF, and dithiothreitol. The apparent Km values for the intact and deglycosylated mucus glycoproteins were 0.45 and 0.89 μM, respectively. The acyltransferase activity of the microsomal enzyme was inhibited by ethanol. With both intact and deglycosylated glycoprotein substrates, the rate of inhibition was proportional to the ethanol concentration up to 0.4 M and was of the competitive type. The K1 values were 0.80 μM for the intact mucus glycoprotein and 1.82 for the deglycosylated glycoprotein. Preincubation of the microsomal enzyme with low concentrations of ethanol (up to 0.5 M) did not seem to exert any additional deterrent effect on acyltransferase activity. Higher concentrations of ethanol (1.0 M and above), however, caused substantial reduction in the transferase activity due to denaturation of the enzyme.",
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Effect of Ethanol on Mucus Glycoprotein Fatty Acyltransferase from Gastric Mucosaα. / Slomiany, Bronislaw L.; Liau, Yun H.; Piasek, Andrzej; Slomiany, Amalia.

In: Biochemistry, Vol. 24, No. 14, 01.07.1985, p. 3514-3521.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Effect of Ethanol on Mucus Glycoprotein Fatty Acyltransferase from Gastric Mucosaα

AU - Slomiany, Bronislaw L.

AU - Liau, Yun H.

AU - Piasek, Andrzej

AU - Slomiany, Amalia

PY - 1985/7/1

Y1 - 1985/7/1

N2 - The enzyme activity that catalyzes the transfer of palmitic acid from palmitoyl coenzyme A to the deacylated intact or deglycosylated gastric mucus glycoprotein was demonstrated in the detergent extracts of the microsomal fraction of antral and body mucosa of the rat stomach. Both types of mucosa exhibited similar acyltransferase activities and acceptor specificities. A 10-14% decrease in the fatty acyltransferase activity was observed with the reduced and S-carboxymethylated mucus glycoprotein, but the proteolytically degraded glycoprotein showed no acceptor capacity. This indicated that the acylation of mucus glycoprotein with fatty acids occurs at its nonglycosylated polypeptide regions and that some of the fatty acids may be linked via thiol esters. Optimum enzyme activity was obtained at pH 7.4 with the detergent Triton X-100, NaF, and dithiothreitol. The apparent Km values for the intact and deglycosylated mucus glycoproteins were 0.45 and 0.89 μM, respectively. The acyltransferase activity of the microsomal enzyme was inhibited by ethanol. With both intact and deglycosylated glycoprotein substrates, the rate of inhibition was proportional to the ethanol concentration up to 0.4 M and was of the competitive type. The K1 values were 0.80 μM for the intact mucus glycoprotein and 1.82 for the deglycosylated glycoprotein. Preincubation of the microsomal enzyme with low concentrations of ethanol (up to 0.5 M) did not seem to exert any additional deterrent effect on acyltransferase activity. Higher concentrations of ethanol (1.0 M and above), however, caused substantial reduction in the transferase activity due to denaturation of the enzyme.

AB - The enzyme activity that catalyzes the transfer of palmitic acid from palmitoyl coenzyme A to the deacylated intact or deglycosylated gastric mucus glycoprotein was demonstrated in the detergent extracts of the microsomal fraction of antral and body mucosa of the rat stomach. Both types of mucosa exhibited similar acyltransferase activities and acceptor specificities. A 10-14% decrease in the fatty acyltransferase activity was observed with the reduced and S-carboxymethylated mucus glycoprotein, but the proteolytically degraded glycoprotein showed no acceptor capacity. This indicated that the acylation of mucus glycoprotein with fatty acids occurs at its nonglycosylated polypeptide regions and that some of the fatty acids may be linked via thiol esters. Optimum enzyme activity was obtained at pH 7.4 with the detergent Triton X-100, NaF, and dithiothreitol. The apparent Km values for the intact and deglycosylated mucus glycoproteins were 0.45 and 0.89 μM, respectively. The acyltransferase activity of the microsomal enzyme was inhibited by ethanol. With both intact and deglycosylated glycoprotein substrates, the rate of inhibition was proportional to the ethanol concentration up to 0.4 M and was of the competitive type. The K1 values were 0.80 μM for the intact mucus glycoprotein and 1.82 for the deglycosylated glycoprotein. Preincubation of the microsomal enzyme with low concentrations of ethanol (up to 0.5 M) did not seem to exert any additional deterrent effect on acyltransferase activity. Higher concentrations of ethanol (1.0 M and above), however, caused substantial reduction in the transferase activity due to denaturation of the enzyme.

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