Primary structure and tetrahydropteroylglutamate binding site of rabbit liver cytosolic 5,10-methenyltetrahydrofolate synthetase
The primary sequence of 5,10-methenyltetrahydrofolate synthetase from rabbit liver was determined by amino acid sequencing of the purified enzyme. The enzyme contains 201 amino acid residues with a predicted mass of 22,779 Da. The enzyme is located in the cytosolic fraction of liver homogenates. Car...
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Veröffentlicht in: | The Journal of biological chemistry 1994-07, Vol.269 (28), p.18429-18433 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The primary sequence of 5,10-methenyltetrahydrofolate synthetase from rabbit liver was determined by amino acid sequencing
of the purified enzyme. The enzyme contains 201 amino acid residues with a predicted mass of 22,779 Da. The enzyme is located
in the cytosolic fraction of liver homogenates. Carbodiimide-activated 5-formyltetrahydropteroylmonoglutamate and the pentaglutamate
form of the substrate both irreversibly inactivate the enzyme by forming a covalent bond to Lys-18. Non-activated 5-formyltetrahydropteroylpentaglutamate
protected against this inactivation. Substrate specificity studies showed that increasing the number of glutamate residues
from zero to five on 5-formyltetrahydropteroate results in a 2 order of magnitude increase in the affinity of the substrate
for the enzyme but only a 3-fold increase in the value of Vmax. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(17)32326-8 |