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Biomedical subjects

J Amir

Publications and source records attributed to J Amir.

At least 145 records · Page 8Linked to original sources
PubMed1972

Purification and properties of adenosine diphosphoglucose pyrophosphorylase from sweet corn.

A 40-fold purification of adenosine diphosphoglucose pyrophosphorylase from sweet corn (Zea mays var. Golden Beauty) revealed the enzyme to be specific for adenosine triphosphate. The enzyme has an absolute requirement for Mg(2+) and is activated by 3-phosphoglycerate and to a lesser extent by ribose-5-phosphate and fructose-6-phosphate. The apparent Km values of the enzyme for glucose-1-phosphate, adenosine triphosphate, pyrophosphate, and adenosine diphosphoglucose are 1.9 x 10(-4), 3.2 x 10(-5), 3.3 x 10(-5), and 6.2 x 10(-4)m, respectively. Pyrophosphate inhibits adenosine diphosphoglucose synthesis competitively (Ki = 3.8 x 10(-7)m), while orthophosphate and sulfate appear to inhibit the reacion noncompetitively. These results show that the production of this sugar nucleotide can be controlled by the concentration of pyrophosphate.

Journal Article↗
PubMed1971

A hereditary immunoglobulin A abnormality: absence of light-heavy-chain assembly. Study of immunoglobulin synthesis in tonsillar cells.

A new immunoglobulin A abnormality, absence of assembly of alpha-chain and light-chain, was found in an adult female suffering from recurrent upper respiratory infection and tonsillitis since childhood, but otherwise healthy. The IgA abnormality was manifest in her serum by the presence of free alpha-chains, in her saliva by the presence of alpha-chains bound to secretory piece, and in her urine by the presence of free alpha-chains and free light-chains. The serum IgG and IgM were found to be complete, containing both heavy-chains and light-chains. Evidence for this immunoglobulin A abnormality was also found in the proposita's mother and elder son, demonstrating it to be a hereditary disorder. Studies performed with patient's tonsillar cells in short-term culture, using amino acids-(14)C, revealed synthesis and secretion of both free alpha-chains and free light-chains, in addition to synthesis and secretion of normally assembled IgG and IgM.

Adult↗
PubMed1970

[The lymphocyte].

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Agammaglobulinemia↗