Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.2.1.22 (cystathionine beta-synthase)
 965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several inherited metabolic disorders of the transsulfuration pathway are discussed. They are hypermethioninemia, homocystinuria, cystathioninuria, beta-mercaptolactate cysteine disulfideuria and sulfite oxidase deficiency (SOD). Primary coverage is given to homocystinuria and SOD. In the case of homocystinuria, metabolic defects include cystathionine beta-synthase deficiency, methylenetetrahydroforate reductase deficiency, and mutations in cobalamin metabolism. Their main clinical pictures, metabolic abnormalities, and treatment are also described. SOD appears in two cases as an isolated enzyme defect and a combined deficiency of sulfite oxidase and xanthine dehydrogenase that share a common molybdenum cofactor. The clinical, biochemical and neurological features of the two disorders are reviewed.
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PMID:[Inherited metabolic disorders of the transsulfuration pathway]. 140 82

A spontaneous mutant of Rhodobacter sphaeroides f. sp. denitrificans IL-106 was found to excrete a large amount of a red compound identified as coproporphyrin III, an intermediate in bacteriochlorophyll and heme synthesis. The mutant, named PORF, is able to grow under phototrophic conditions but has low levels of intracellular cysteine and glutathione and overexpresses the cysteine synthase CysK. The expression of molybdoenzymes such as dimethyl sulfoxide (DMSO) and nitrate reductases is also affected under certain growth conditions. Excretion of coproporphyrin and overexpression of CysK are not directly related but were both found to be consequences of a diminished synthesis of the key metabolite S-adenosylmethionine (SAM). The wild-type phenotype is restored when the gene metK encoding SAM synthetase is supplied in trans. The metK gene in the mutant strain has a mutation leading to a single amino acid change (H145Y) in the encoded protein. This point mutation is responsible for a 70% decrease in intracellular SAM content which probably affects the activities of numerous SAM-dependent enzymes such as coproporphyrinogen oxidase (HemN); uroporphyrinogen III methyltransferase (CobA), which is involved in siroheme synthesis; and molybdenum cofactor biosynthesis protein A (MoaA). We propose a model showing that the attenuation of the activities of SAM-dependent enzymes in the mutant could be responsible for the coproporphyrin excretion, the low cysteine and glutathione contents, and the decrease in DMSO and nitrate reductase activities.
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PMID:Coproporphyrin excretion and low thiol levels caused by point mutation in the Rhodobacter sphaeroides S-adenosylmethionine synthetase gene. 2003 86