A comparison of the inhibitory action of 5-(substituted-benzyl)-2,4-diaminopyrimidines on dihydrofolate reductase from chicken liver with that from bovine liver

1982 ◽  
Vol 25 (4) ◽  
pp. 435-440 ◽  
Author(s):  
Ren Li Li ◽  
Corwin Hansch ◽  
Bernard T. Kaufman
Keyword(s):  
Dihydrofolate Reductase ◽  
Inhibitory Action ◽  
Bovine Liver ◽  
Chicken Liver

A fluorescence study of substrate and inhibitor binding to bovine liver dihydrofolate reductase

1989 ◽  
Vol 21 (3) ◽  
pp. 291-295 ◽  
Author(s):  
Paolo Degan ◽  
Patrizia Carpano ◽  
Giovanni Cercignani ◽  
Giorgio Montagnoli
Keyword(s):  
Dihydrofolate Reductase ◽  
Bovine Liver ◽  
Fluorescence Study ◽  
Inhibitor Binding

Primary structure of chicken liver dihydrofolate reductase

Biochemistry ◽  
1980 ◽  
Vol 19 (4) ◽  
pp. 667-678 ◽  
Author(s):  
A. Ashok Kumar ◽  
Dale T. Blankenship ◽  
Bernard T. Kaufman ◽  
James H. Freisheim
Keyword(s):  
Dihydrofolate Reductase ◽  
Primary Structure ◽  
Chicken Liver

scholarly journals Activation of chicken liver dihydrofolate reductase by urea and guanidine hydrochloride is accompanied by conformational change at the active site

1996 ◽  
Vol 315 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Ying-xin FAN ◽  
Ming JU ◽  
Jun-mei ZHOU ◽  
Chen-lu TSOU
Keyword(s):  
Catalytic Activity ◽  
Dihydrofolate Reductase ◽  
Conformational Changes ◽  
Active Site ◽  
Guanidine Hydrochloride ◽  
Chicken Liver ◽  
Peptide Fragments ◽  
Enhanced Fluorescence ◽  
Compact Structure ◽  
Mouse Leukaemia

It has been reported that the activation of dihydrofolate reductase (DHFR) from L1210 mouse leukaemia cells by KCl or thiol modifiers is accompanied by increased digestibility by proteinases [Duffy, Beckman, Peterson, Vitols and Huennekens (1987) J. Biol. Chem. 262, 7028–7033], suggesting a loosening up of the general compact structure of the enzyme. In the present study, the peptide fragments liberated from the chicken liver enzyme by digestion with trypsin in dilute solutions of urea or guanidine hydrochloride (GuHCl) have been separated by FPLC and sequenced. The sequences obtained are unique when compared with the known sequence of DHFR and thus allow the points of proteolytic cleavage identified for the urea- and GuHCl-activated enzyme to be at or near the active site. It was also indicated by the enhanced fluorescence of 2-p-toluidinylnaphthalene 6-sulphonate that conformational changes at the active site in dilute GuHCl parallel GuHCl activation. The above results indicate that the activation of DHFR in dilute denaturants is accompanied by a loosening up of its compact structure especially at or near the active site, suggesting that the flexibility at its active site is essential for the full expression of its catalytic activity.

Enzymic inhibition assay for methotrexate with a discrete analyzer, the ABA-100.

1980 ◽  
Vol 26 (2) ◽  
pp. 335-338
Author(s):  
L F Brown ◽  
G F Johnson ◽  
D L Witte ◽  
R D Feld
Keyword(s):  
Enzyme Activity ◽  
Dihydrofolate Reductase ◽  
Present Method ◽  
Bovine Liver ◽  
Sign Test ◽  
Inhibition Assay ◽  
Paired Data ◽  
Standard Curve ◽  
Radioimmunoassay Method

Abstract We adapted an inhibition assay for methotrexate, involving dihydrofolate reductase from bovine liver, for use with a discrete analyzer (the ABA-100). The analyzer was used both for dilution and a 5-min pre-incubation of the sample with NADPH--enzyme reagent, and for the assay itself. The standard curve was linear between 10 and 120 microgram/L. Without pre-incubation the standard curve was nonlinear. The presence of albumin in the NADPH--enzyme reagent enhanced both enzyme activity and stability. Within-run precision (CV) was 2.0% (n = 24), run-to-run precision 7.1% (n = 49). Results obtained on patients' samples (29 sera, 15 urines, 18 cerebrospinal fluids) by the present method and a radioimmunoassay method did not differ statistically (p greater than 0.05) when the paired data were analyzed by use of the sign test and Wilcoxon's ranked sign test.

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