Rat intestinal nucleotide-sugar pyrophosphatase. Localization, partial purification, and substrate specificity

Area of Science:

• Biochemistry
• Gastroenterology
• Enzymology

Background:

• Nucleotide-sugar pyrophosphatase plays a role in cellular processes.
• Understanding its localization and function in the gastrointestinal tract is important.

Purpose of the Study:

• To investigate the nucleotide-sugar pyrophosphatase activity in the rat small intestine.
• To characterize the enzyme responsible for this activity.

Main Methods:

• Utilized GDP-[14C]Man as a substrate to assay enzyme activity.
• Fractionated and purified the enzyme from rat small intestine brush-border membranes.
• Performed biochemical assays including electrophoresis, thermal inactivation, and inhibition studies.

Main Results:

• Highest enzyme activity was found in the proximal small intestine, specifically in villus tip cells.
• Purified brush-border membranes showed significant enrichment of the enzyme.
• The purified enzyme hydrolyzed nucleotide sugars, FAD, and p-nitrophenyl-5 omino-thymidylate.

Conclusions:

• The study identified a single enzyme, a 5 omino-nucleotide phosphodiesterase, responsible for nucleotide-sugar pyrophosphatase, phosphodiesterase I, and FAD pyrophosphatase activities.
• This enzyme exhibits specific regional, cellular, and subcellular localization within the rat small intestine.