Free protein amino acids of some Mediterranean Siphonales

Fifteen free protein amino acids have been quantitatively determined in nine green algae belongin to the order Siphonales. In all the species examined, aspartic acid, glutamic acid, alanine, glycine and serine dominate. Wide differences of the relative amounts of these amino acids in the various regardless of the genus were observed.     

Regulation of intestinal protein metabolism by amino acids

Gut homeostasis plays a major role in health and may be regulated by quantitative and qualitative food intake. In the intestinal mucosa, an intense renewal of proteins occurs, at approximately 50 % per day in humans. In some pathophysiological conditions, protein turnover is altered and may contribute to intestinal or systemic diseases. Amino acids are key effectors of gut protein turnover, both as constituents of proteins and as regulatory molecules limiting intestinal injury and maintaining intestinal functions. Many studies have focused on two amino acids: glutamine, known as the preferential substrate of rapidly dividing cells, and arginine, another conditionally essential amino acid. The effects of glutamine and arginine on protein synthesis appear to be model and condition dependent, as are the involved signaling pathways. The regulation of gut protein degradation by amino acids has been minimally documented until now. This review will examine recent data, helping to better understand how amino acids regulate intestinal protein metabolism, and will explore perspectives for future studies.     

Interrelationships between water and cellular metabolism in Artemia cysts VII. Free amino acids

The concentration of total ninhydrin-positive material (NPM) soluble in 5% trichloroacetic acid was measured in cysts of the brine shrimp, Artemia salina, as a function of hydration level. No net change in NPM was observed until the cysts had achieved a water content of about 0.65 g H₂O/g of initially dry cysts. Above this hydration threshold the NPM content increased markedly. Examination of the free amino acid composition of cysts incubated at selected hydration levels revealed that almost all of the amino acids underwent net change above the hydration threshold. However, just below this threshold, the free amino acid composition was essentially the same as in fully dried cysts. The activity generating net changes in the concentration of free amino acids above the hydration threshold was shown to be metabolic in nature and restricted to the cellular component of the cyst.