In normal individuals, the main route for tyrosine degradation is the hepatic pathway tyrosine→4-hydroxyphenylpyruvic acid→homogentisic acid→CO(2). Quantitatively minor pathways, in large part extrahepatic, are: tyrosine→tyramine→octopamine and tyrosine→dopa→catecholamines.In cirrhosis, the main hepatic pathway is blocked to varying degrees at the first three stages. This appears to be due to l...

In recent years the metabolic fate of the individual carbon atoms of the aromatic amino acids has been rather completely elucidated, largely by the use of isotopic labeling techniques (l-3). Very little is known, however, concerning the enzymatic mechanisms whereby the complicated transformation of phenylalanine and tyrosine to acetoacetate is effected. A recent contribution in this direction w...

The virulence of Legionella pneumophila is dependent upon its capacity to acquire iron. To identify genes involved in expression of its siderophore, we screened a mutagenized population of L. pneumophila for strains that were no longer able to rescue the growth of a ferrous transport mutant. However, an unusual mutant was obtained that displayed a strong inhibitory effect on the feoB mutant. Du...

Alkaptonuria is an extremely rare condition, which is due to a defect in protein metabolism. The most probable explanation is that it is due to the absence of the particular enzyme which normally effects a particular stage in the complete destruction of tyrosine and phenyl-alanine. Alkapton is the intermediate product beyond which metabolism can no further go, and it is excreted as such in the ...

INTRODUCTION Alkaptonuria is a very rare inborn error of amino acid metabolism due to deficient homogentisic acid (HGA) oxidase enzyme leading to accumulation of HGA in plasma, cartilage, other tissues of human body and its excretion in urine. It has both systemic and peripheral signs and symptoms. Though low back is a common symptom of alkaptonuria but, in the absence of ochronosis it is rare....

Background: Alkaptonuria (AKU) or ochronosis is a rare progressive degenerative arthropathy that results from deficiency of enzyme homogentisate 1,2 dioxygenase (HGD). The features include arthritis of the spine and in larger peripheral joints, with chondrocalcinosis. In this paper, we present a case of alkaptonuria in a 54 year old woman in Tehran, Iran. Case Presentation: A 54 year old woman ...