scholarly journals The complete amino acid sequence of the folate-binding protein from cow's milk

1984 ◽  
Vol 49 (1) ◽  
pp. 123-131 ◽  
Author(s):  
IB Svendsen ◽  
Steen Ingemann Hansen ◽  
Jan Holm ◽  
Jørgen Lyngbye
2012 ◽  
Vol 19 (3) ◽  
pp. 105-109
Author(s):  
A SUBANDRATE ◽  
DWIRINI RETNO GUNARTI ◽  
MOHAMAD SADIKIN

2001 ◽  
Vol 21 (6) ◽  
pp. 733-743 ◽  
Author(s):  
Jan Holm ◽  
Steen Ingemann Hansen

Binding of folate (pteroylglutamate) and 5-methyltetrahydrofolate, the major endogenous form of folate, to folate binding protein purified from cow's milk was studied at 7°C to avoid degradation of 5-methyltetrahydrofolate. Both folates dissociate rapidly from the protein at pH 3.5, but extremely slowly at pH 7.4, most likely due to drastic changes in protein conformation occurring after folate binding. Dissociation of 5-methyltetrahydrofolate showed no increase at 37°C suggesting that protein-bound-5-methyltetrahydrofolate is protected against degradation. Binding displayed two characteristics, positive cooperativity and a binding affinity that increased with decreasing concentrations of the protein. The binding affinity of folate was somewhat greater than that of 5-methyl tetrahydrofolate, in particular at pH 5.0. Ligand-bound protein exhibited concentration-dependent polymerization (8-mers formed at 13 μM) at pH 7.4. At pH 5.0, only folate-bound forms showed noticeable polymerization. The fact that folate at pH 5.0 surpasses 5-methyltetrahydrofolate both with regard to binding affinity and ability to induce polymerization suggests that ligand binding is associated with conformational changes of the protein which favor polymerization.


2001 ◽  
Vol 21 (3) ◽  
pp. 305-313 ◽  
Author(s):  
Jan Holm ◽  
Steen Ingemann Hansen ◽  
Mimi Høier-Madsen

A high-affinity folate binding protein was isolated and purified from cow's milk by a combination of cation exchange chromatography and methotrexate affinity chromatography. Chromatofocusing studies revealed that the protein possessed isoelectric points in the pH-interval 8–7. Polymers of the protein prevailing at pH values close to the isoelectric points seemed to be more hydrophobic than monomers present at pH 5.0 as evidenced by hydrophobic interaction chromatography and turbidity (absorbance at 340 nm) in aqueous buffer solutions (pH 5–8). Ligand binding seemed to induce a conformation change that decreased the hydrophobicity of the protein. In addition, Ligand binding quenched the tryptophan fluorescence of folate binding protein suggesting that tryptophan is present at the binding site and/or ligand binding induces a conformation change that affects tryptophan environment in the protein. There was a noticeable discordance between the ability of individual folate analogues to compete with folate for binding and the quenching effect.


2009 ◽  
Vol 42 (1) ◽  
pp. 77-80 ◽  
Author(s):  
Jan Holm ◽  
Steen Ingemann Hansen ◽  
Jørgen Lyngbye

1989 ◽  
Vol 185 (3) ◽  
pp. 569-572 ◽  
Author(s):  
Roberto TIRINDELLI ◽  
Jeffrey N. KEEN ◽  
Andrea CAVAGGIONI ◽  
Elias E. ELIOPOULOS ◽  
John B. C. FINDLAY

2001 ◽  
Vol 21 (6) ◽  
pp. 745-753 ◽  
Author(s):  
Jan Holm ◽  
Steen Ingemann Hansen

The ligand binding and aggregation behavior of cow's milk folate binding protein depends on hydrogen ion concentration and buffer composition. At pH 5.0, the protein polymerizes in Tris-HCl subsequent to ligand binding. No polymerization occurs in acetate, and binding is markedly weaker in acetate or citrate buffers as compared to Tris-HCl. Polymerization of ligand-bound protein was far more pronounced at pH 7.4 as compared to pH 5.0 regardless of buffer composition. Binding affinity increased with decreasing concentration of protein both at pH 7.4 and 5.0. At pH 5.0 this effect seemed to level off at a protein concentration of 10−6 M which is 100–1000 fold higher than at pH 7.4. The data can be interpreted in terms of complex models for ligand binding systems polymerizing both in the absence or presence of ligand (pH 7.4) as well as only subsequent to ligand binding (pH 5.0).


Biochimie ◽  
1998 ◽  
Vol 80 (2) ◽  
pp. 109-116
Author(s):  
B. Laine ◽  
F. Chartier ◽  
F. Culard ◽  
D. Bélaïche ◽  
P. Sautière

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