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Chapter-07 Nonprotein Nitrogenous Substances

BOOK TITLE: An Easy Guide for Practical Biochemistry

Author
1. D’sa Divya Shanthi
2. Lakshmi Sowbhagya
ISBN
9789352702633
DOI
10.5005/jp/books/14203_8
Edition
2/e
Publishing Year
2018
Pages
8
Author Affiliations
1. Shimoga Institute of Medical Sciences, Shimoga, Karnataka, India, Subbaiah Institute of Medical Sciences, Shivamogga, Karnataka, India
2. Shimoga Institute of Medical Sciences, Shimoga, Karnataka, India, Sambhram Institute of Medical Sciences and Research, Kolar, Karnataka, India
Chapter keywords
Nonprotein nitrogenous substance, urea, uric acid, creatine, Jaffe’s test, murexide test, Schiff’s test, specific urease test, sodium hypobromite test

Abstract

This chapter describes nonprotein nitrogenous substances. Nonprotein nitrogenous substances include all nitrogenous substances other than proteins. Most important NPN substances present in urine are uric acid, urea, creatinine and ammonia. Urea is the end product of protein catabolism. It is synthesized in the liver. Normal blood urea level is 15–45 mg/dL and normal level of urea excreted in urine is 25–30 g/day. Uric acid is the end product of catabolism of purines, in human body. It is synthesized in the liver and excreted through urine as urates. Normal level of uric acid excreted in urine is 250–750 mg/day. Uric acid is sparingly soluble in water but soluble in alkaline solution. Creatine is found in muscle as creatine phosphate plays an important role in muscular contraction. Creatine is synthesized from three amino acids, glycine, arginine and methionine.

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