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In this article we will discuss about the Digestion and Absorption of Nucleoproteins and Nucleic Acids from Gastrointestinal Tract.
Digestion of Nucleoproteins and Nucleic Acids:
Stomach:
The nucleoproteins of many foods are cleaved by the acidity of the gastric juice into proteins (histones, protamine’s etc.) and nucleic acids:
The proteins are hydrolyzed by proteases present in the digestive juices to amino acids in the same way as the dietary proteins.
Small Intestine:
Nucleic acids are hydrolyzed by three groups of enzymes:
1. Nucleases.
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2. Nucleotidases.
3. Nucleosidases.
Nucleases are of two types:
1. Ribonucleases.
2. Deoxyribonucleases.
Ribonucleases hydrolyze RN A and deoxyribonucleases hydrolyze DNA. The end products are nucleotides.
Nucleotidases hydrolyze nucleotides into nucleosides and phosphoric acid.
Nucleosidases hydrolyze nucleosides into purine or pyrimidine base and the pentose sugars (ribose or deoxyribose).
All of the above mentioned reactions are given in Fig. 16.10.
Absorption of Nucleoproteins and Nucleic Acids:
1. The purine or pyrimidine base and the pentose’s are absorbed in the small intestine.
2. Certain amounts of nucleosides and pentose phosphates may also be absorbed. Most of the tissues contain nucleosidases which hydrolyze nucleosides absorbed from the intestines.
