Reversible inhibition by pyridoxal 5'-phosphate and irreversible inactivation by urea and guanidine hydrochloride of thymidylate synthase from Lactobacillus leichmannii.
Pyridoxal 5'-phosphate reversibly inhibited thymidylate synthase from Lactobacillus leichmannii. The inhibition was competitive with dUMP (Ki = 1 microM) and non-competitive with 5,10-CH2-THF (Ki = 0.08 microM). Treatment of native or pCMB-treated enzyme with urea (5 M) or guanidine hydrochloride (4 M) resulted in inactivation and dissociation of the homodimer (74 kDa) into monomer (37 kDa).
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Radiation Biology and Biochemistry Division, Bhabha Atomic Research Centre, Mumbai, India. rbbd@magnum.barc1.ernet.in
D019281:Dimerization; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019791:Guanidine / Q000494:pharmacology; D007778:Lactobacillus / Q000201:enzymology*; D011487:Protein Conformation / Q000187:drug effects; D011732:Pyridoxal Phosphate / Q000494:pharmacology; D013940:Thymidylate Synthase / Q000037:antagonists & inhibitors* / Q000737:chemistry; D014508:Urea / Q000494:pharmacology
D004791:Enzyme Inhibitors; D011732:Pyridoxal Phosphate; D014508:Urea; D013940:Thymidylate Synthase; D019791:Guanidine