Amino acids in blood

Methods have been developed for analysis or deterrnination of free amino acids in blood, food, and feedstocks (116). In proteins, the first step is hydrolysis, then separation if necessary, and finally, analysis of the amino acid mixture. 

Molecules that contain an equal number of ionizable groups of opposite charge and that therefore bear no net charge are termed zwitterions. Amino acids in blood and most tissues thus should be represented as in A, below. 

Ranges in Amino Acids in Blood Plasma Range, mg./lOO ml. 

Gas chromatographic methods can aid in these diagnoses, for amino acids in blood and urine and for organic acids in urine. 

C13. Christensen, P. J., Date, J. W., Schoenheyder, F., and Volqvartz, K., Amino-acids in blood plasma and urine during pregnancy. Scand. J. Clin, b Lab. Invest. 9, 54-61 (1957). 

If the history, physical findings, and laboratory results are suggestive but not conclusive of a particular mitochondrial disease (e.g., MELAS), then a second tier of tests is performed. These include blood and CSF lactate and pyruvate, as well as the lactate/pyruvate ratio timed or random measurement of amino acids in blood, urine, and CSF organic acids in urine and CSF and ketones and free and total carnitine in blood and urine. 

Amino acids in blood are filtered through the glomerular membranes but are normally reabsorbed in the renal tubules by saturable transport systems (see Chapter 45). Hence, high blood levels of amino acids may result in significant renal excretion (aminoaciduria). In normal individuals, aminoacidm ia is transient and is associated with protein intake in excess of amino acid requirements for repletion of the body pool. The mechanism of reabsorption is not fully understood, although it is known to be an active transport system dependent on membrane-bound carriers and intraluminal Na concentration. Four different transport systems... 

Levels of Other Amino Acids in Blood, Cerebrospinal Fluid, and Urine... 

Cl 6. Culley, W. J., A rapid and simple thin layer chromatographic method for amino acids in blood. Clin. Chem. 16, 902-907 (1969). 

Imbalanced states with other circulating amino acids in blood... 

The study of amino acids is indeed facilitated by different factors the number of naturally occurring amino acids is relatively limited techniques of a fairly good selectivity are available for the characterization of amino acids finally, the concentration of amino acids in blood and urine is not notably influenced by the diet, within the limits of normal variations in protein intake (B17). Such factors do not exist in the case of organic acids a very large number of such acids must be considered as potential constituents of blood and urine no selective method of characterization is available finally, their concentration depends largely, for many, upon diet. Despite these differences, a parallelism can be shown between the historical development of our knowledge in the two fields. 

Adult onset olivopontocerebellar degeneration (OPCD) is a syndrome characterized by ataxia and motor incoordination. Individuals with this disorder have a deficiency in Glu dehydrogenase that impairs the metabolism of Glu. Ingestion of Glu causes abnormally high levels of the amino acid in blood (Plaitakis et al., 1984). A similar accumulation of Glu occurring in the CNS could cause a slowly developing neuronal degeneration. 

Multiple development techniques [unidimensional multiple development (UMD) and incremental multiple development (IMD)] were also used to separate the components of a reference solution of amino acids in blood plasma on cellulose plates eluted with acetonitrile-water (8 2 y/y)P ... 

A Micromethod for the Clinical Chemistry Routine Analysis of Amino Acids in Blood and Urine by Capillary Gas-Liquid Chromatography of Isobutyl Esters N(0)-Heptafluorobutyrare Derivatives... 

Determination of Amino Acids in Blood Osaka-furitsu Koshu Eisei Kenkyusho Kenkyu Hokoku, Shokuhin Eisei Hen 10 67-71 (1979) GA 93 3210z... 

Bhushan (1991) on amino acids and their derivatives their new review includes references through 1994. Jain (1996) has reviewed studies on the applications of TLC to amino acid analysis of biological fluids and tissues. Such analyses are important in making diagnoses of inborn errors of amino acid metabolism. It was noted by Jain (1996) that TLC has proved useful to screen and quantify abnormal amounts of free amino acids in blood and urine samples. Shalaby (1996) in his chapter on TLC in food analysis has provided some protocols on amino acid analysis following the hydrolysis of protein samples. Fried and Haseeb (1996) in their chapter on TLC in parasitology have provided some information on the analysis of free pool amino acids from tissues of parasites and from the hemo-lymph of mosquitoes infected with Plasmodium (the malaria organism). 

FIGURE 11.6 (a) MMC for amino acids detected in the blood extract. Peaks identified as amino acids in blood extract based on mass and reduced mobility data matched with that measured for standard solutions of amino acids, (b) MMCs for various classes of metabolites detected in the blood sample. Only protonated ions of metabolites constitute the MMCC (except for the sugars as sodium adducts). (Reprinted from Dwivedi, P. Shultz, A. Hill, H. H. Jr. Int. J. Mass Spectrom. Accepted for publication. Copyright 2009, in press.)... 

In spite of its disadvantages, platinum has been used for nonenzymatic detection of blood glucose. One of the drawbacks of the platinum electrode is its catalytic activity for the electrochemical oxidation of glucose drops which can be seriously affected by the chloride ion present in physiological fluids. On the other hand, amino acids, biochemicals like ascorbic acid, creatinine, epinephrine, and urea in blood can destroy the platinum electrode. In this way, if blood proteins occupy the catalytic sites on the platinum surface, the detection of glucose on platinum will be deteriorated. Due to the fact that glucose oxidation can be inhibited by many biochemicals and amino acids in blood, this can lead to a loss of sensitivity when glucose is detected with platinum. ... 

---