Effect of ethanol on the peptic degradation of gastric mucus glycoprotein

W. Laszewicz; Amalia Slomiany; V. Murty; Y. H. Liau; Bronislaw Slomiany

doi:10.1159/000199177

Effect of ethanol on the peptic degradation of gastric mucus glycoprotein

W. Laszewicz, Amalia Slomiany, V. Murty, Y. H. Liau, Bronislaw Slomiany

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13 Scopus citations

Abstract

The effect of ethanol on the proteolytic activity of pepsin towards gastric mucus glycoprotein was investigated. Undegraded mucus glycoprotein isolated from pig stomach was incubated with pepsin in the presence and absence of ethanol, and the released α-amino residues were quantitated by the trinilrophenylation procedure. In the absence of ethanol the rate of proteolysis was proportional to mucus glycoprotein concentration up to 450 μg and remained constant with time of incubation for at least 30 min. The apparent K_m value of pepsin for pig gastric mucus glycoprotein was 8.7 × 10^-7 M. The proteolytic activity of pepsin towards mucus glycoprotein was inhibited by ethanol. The rate of inhibition was proportional to the ethanol concentration up to 0.8 M and was of competitive type. The apparent K_I value calculated from the double-reciprocal plots for ethanol was 2.2 × 10^-6 M. The inhibitory effect of ethanol on the proteolysis of gastric mucus glycoprotein may be of physiological significance.

Original language	English (US)
Pages (from-to)	47-53
Number of pages	7
Journal	Digestion
Volume	31
Issue number	1
DOIs	https://doi.org/10.1159/000199177
Publication status	Published - Jan 1 1985
Externally published	Yes

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All Science Journal Classification (ASJC) codes

Gastroenterology

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Laszewicz, W., Slomiany, A., Murty, V., Liau, Y. H., & Slomiany, B. (1985). Effect of ethanol on the peptic degradation of gastric mucus glycoprotein. Digestion, 31(1), 47-53. https://doi.org/10.1159/000199177

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AU - Slomiany, Amalia

AU - Murty, V.

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AU - Slomiany, Bronislaw

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N2 - The effect of ethanol on the proteolytic activity of pepsin towards gastric mucus glycoprotein was investigated. Undegraded mucus glycoprotein isolated from pig stomach was incubated with pepsin in the presence and absence of ethanol, and the released α-amino residues were quantitated by the trinilrophenylation procedure. In the absence of ethanol the rate of proteolysis was proportional to mucus glycoprotein concentration up to 450 μg and remained constant with time of incubation for at least 30 min. The apparent Km value of pepsin for pig gastric mucus glycoprotein was 8.7 × 10-7 M. The proteolytic activity of pepsin towards mucus glycoprotein was inhibited by ethanol. The rate of inhibition was proportional to the ethanol concentration up to 0.8 M and was of competitive type. The apparent KI value calculated from the double-reciprocal plots for ethanol was 2.2 × 10-6 M. The inhibitory effect of ethanol on the proteolysis of gastric mucus glycoprotein may be of physiological significance.

AB - The effect of ethanol on the proteolytic activity of pepsin towards gastric mucus glycoprotein was investigated. Undegraded mucus glycoprotein isolated from pig stomach was incubated with pepsin in the presence and absence of ethanol, and the released α-amino residues were quantitated by the trinilrophenylation procedure. In the absence of ethanol the rate of proteolysis was proportional to mucus glycoprotein concentration up to 450 μg and remained constant with time of incubation for at least 30 min. The apparent Km value of pepsin for pig gastric mucus glycoprotein was 8.7 × 10-7 M. The proteolytic activity of pepsin towards mucus glycoprotein was inhibited by ethanol. The rate of inhibition was proportional to the ethanol concentration up to 0.8 M and was of competitive type. The apparent KI value calculated from the double-reciprocal plots for ethanol was 2.2 × 10-6 M. The inhibitory effect of ethanol on the proteolysis of gastric mucus glycoprotein may be of physiological significance.

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10.1159/000199177