Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Modification of pig kidney fructose 1,6-bisphosphatase with 2,3-butanedione (in the presence of AMP) results in the loss of activation of the enzyme by monovalent cations. Under these conditions about 8 arginyl residues per mole of enzyme were modified. No other residues were modified. No loss of monovalent cation activation occurs when modification with 2,3-butanedione is carried out in the presence of AMP plus the substrate fructose 1,6-bisphosphate and 3.2 less arginyl residues were modified. Since fructose 1,6-bisphosphatase contains 4 subunits, it is suggested that one arginyl residue per subunit plays an essential role in monovalent cation activation of the enzyme. Studies on sulfhydryl group reactivity toward 5,5'-dithiobis(2-nitrobenzoic acid) explain the protection exerted by fructose 1,6-bisphosphate against the loss of monovalent cation activation in terms of an enzyme conformational change induced by substrate, which makes unreactive the essential arginyl residue. The results of the present paper, as well as previous evidence, are discussed in terms of the mechanism of monovalent cation activation of fructose 1,6-biphosphatase.
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PMID:Functional consequences of modifying highly reactive arginyl residues of fructose 1,6-bisphosphatase. Loss of monovalent cation activation. 16 92

Bovine liver fructose 1,6-bisphosphatase bound 4 mol of its allosteric inhibitor AMP per mole of enzyme with half-saturation at 17 mumol/l AMP. The presence of a mixture of positive and negative cooperativity in the binding of AMP to the enzyme was suggested by several procedures for analyzing binding data. In particular, calculation of the intrinsic binding constants for AMP yielded the relationships: K1' less than K2' greater than K3' less than K4', indicating mixed cooperativity.
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PMID:Binding of adenosine 5'-monophosphate to bovine liver fructose 1,6-bisphosphatase. 22 77

The relationship between derivatization of reactive cysteine residues with N-ethylmaleimide and a partial desensitization of fructose 1,6-bisphosphatase to AMP inhibition was studied. AMP desensitization of the enzyme was found to be dependent on the activity assay conditions used. When the assay was performed in the presence of high levels of monovalent cations (150 mM), the AMP affinity of the enzyme decreased with the chemical modification. The apparent loss of sensitivity toward AMP was accompanied by an uptake of 1 mole of N-ethylmaleimide/mole of enzyme subunit. However, the modified enzyme did not show alteration in AMP inhibition in the absence of K+. Evidence was obtained that K+ induces a conformational change on the enzyme derivative, which hinders AMP interaction with the protein. The results point to the importance of selecting suitable conditions for the study of the regulatory properties in allosteric enzymes.
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PMID:The interaction of monovalent cations with fructose 1,6-bisphosphatase modified by N-ethylmaleimide and its relation with AMP inhibition. 155 47