Pea Leaf Glutamine Synthetase: Regulatory Properties 1
AUTOR(ES)
O'Neal, Thomas Denny
RESUMO
Of a variety of purine and pyrimidine nucleotides tested, only ADP and 5′AMP significantly inhibited the Mg2+-dependent activity of pea leaf glutamine synthetase. They were less effective inhibitors where Mn2+ replaced Mg2+. They were competitive inhibitors with respect to ATP, with inhibition constant (Ki) values of 1.2 and 1.8 mm, respectively. The energy charge significantly affects the activity of glutamine synthetase, especially with Mg2+. Of a variety of amino acids tested, l-histidine and l-ornithine were the most inhibitory, but significant inhibition was seen only where Mn2+ was present. Both amino acids appeared to compete with l-glutamate, and the Ki values were 1.9 mm for l-histidine (pH 6.2) and 7.8 mm for l-ornithine (pH 6.2). l-Alanine, glycine, and l-serine caused slight inhibition (Mn2+-dependent activity) and were not competitive with ATP or l-glutamate.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=541748Documentos Relacionados
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