Protein metabolism and involvement of different factors

Abstract

The balance between protein synthesis and breakdown (protein turnover) regulates whole - body protein mass. Synthesis of new proteins is achieved by complex series of reactions. Protein breakdown plays a major role in muscle growth and atrophy and in different tissues in body three major proteolytic systems are known. Most methods for quantifying protein synthesis and breakdown are based on isotopic techniques. The most important factors of the regulation of protein metabolism are presented: hormones, substrates, nutrients of the diet, genetic constitution and age of the animal. The highest protein synthesis rate achieve tissues of gastrointestinal tract: small intestine 103.4 % day^-1 and large intestine 62.1 % day^-1, and liver, 105.4 % day^-1 followed by the peripheral tissues (skeletal muscles). Skeletal muscles contain the highest amount of protein. Whole body protein synthesis rate of the young rats is around 30 % day^-1 and decreases with age.