The influence of uncoordinated histidines on iron release from transferrin. A chemical modification study.

Thompson, Carl P.; Grady, John K.; Chasteen, N. Dennis

doi:10.1016/s0021-9258(18)69280-4

Cited by 28 publications

(15 citation statements)

References 28 publications

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“…Fe-HC03-Tf* + L^L-Fe-HC03-Tf* (10) *-2 L-Fe-HC03-Tf* 2=± Fe-L + apoTf + HC03 (11) of ferric transferrin. This mechanism accounts for the observation of saturation kinetics during the removal of iron by ligands such as acetohydroxamic acid28 and LICAMS31 without the accumulation of detectable concentrations of any mixed-ligand intermediates.…”

Section: Discussionmentioning

confidence: 99%

Kinetics of iron removal from monoferric and cobalt-labeled monoferric transferrins by diethylenetriaminepenta(methylenephosphonic acid) and diethylenetriaminepentaacetic acid

Harris¹,

Bali²,

Crowley³

1992

Inorg. Chem.

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Section: Discussionmentioning

confidence: 99%

Kinetics of iron removal from monoferric and cobalt-labeled monoferric transferrins by diethylenetriaminepenta(methylenephosphonic acid) and diethylenetriaminepentaacetic acid

Harris¹,

Bali²,

Crowley³

1992

Inorg. Chem.

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“…It was found that the Sigma sample had to be dialyzed extensively against 100 mM sodium perchlorate (at 4 °C) before use to avoid occurrence of spurious heat signals during titration. The C-site-saturated, monoferric hTF (Fec-hTF, with bicarbonate bound as the synergistic anion) was prepared according to the method described by Thompson et al (1986).…”

Section: Methodsmentioning

confidence: 99%

“…were determined spectrophotometrically at 278 nm using extinction coefficients of 93 000 M™1 cm-1 (Chasteen, 1977) for hTF and 40 000 M™1 cm™1 for hTF/2N (Lin et al, 1993). The concentration of Fec-hTF was determined spectrophotometrically at 465 nm using an extinction coefficient of 2500 M™1 cm™1 (Thompson et al, 1986). The preparation of Fe-NTA (in a 1:2 molar ratio) has been described previously (Lin et al, 1991).…”

Section: Methodsmentioning

confidence: 99%

“…It is well-documented that NTAchelated ferric ion binds preferentially to the C-site of hTF (Aisen et al, 1978;Brock, 1985). The preference of Fe-NTA to bind to the C-site first is so strong that monoferric transferrin (Fe<r-hTF), prepared by mixing Fe-NTA with apo-hTF in a 1:1 molar ratio in 0.1 M HEPES and 25 mM NaHCOs at neutral pH and then dialyzing out the NTA (Thompson et al, 1986;Bali & Harris, 1990), shows virtually no detectable binding at the N-site. Therefore, the profiles for first five injections in Figure 1, which saturated 50% of the sites of apo-hTF, must result from binding to the C-site, while those for injections 6-10 arise from binding to the N-site.…”

Section: Methodsmentioning

confidence: 99%

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Calorimetric studies of the binding of ferric ions to human serum transferrin

Lin¹,

Mason²,

Woodworth³

et al. 1993

Biochemistry

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The binding of ferric ions, chelated with nitrilotriacetate, to human serum transferrin (hTF) has been studied using ultrasensitive titration calorimetry. Studies were done in both the presence and the absence of the synergistic bicarbonate anion. It was found that the C-site of hTF is capable of weakly binding bicarbonate (K of 250 M-1, delta H of -8 kcal) at the binding site even before ferric ion is added, although this does not happen to the same extent at the N-site. When preinsertion of the bicarbonate ion occurs, then ferric ion can subsequently bind very quickly to the C-site. Although the chelated ferric ion can bind weakly to the N-site in a fast reaction, the insertion of the bicarbonate ion occurs subsequently in a slow endothermic reaction. Binding of ferric ion to both sites is quickly reversible in the absence of bicarbonate but becomes kinetically controlled for long periods of time once bicarbonate has inserted into the metal-binding site due to the long time required for release of ferric ion. Estimates of the heats of binding to each site, apparent binding constants, and heat capacities of binding are made for different sets of solution conditions. Results from this study are compared to earlier results with ovotransferrin (Lin, L.-N., Mason, A. B., Woodworth, R. C., & Brandts, J. F. (1991) Biochemistry 30, 11660-11669), with major differences and some similarities noted.

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“…Bullfrog saxiphilin resembles transferrins in having pH dependent binding of STX, a property attributable to a conserved histidine residue in bullfrog saxiphilin 133 to that known to be the pH trigger in transferrins. 130,134 Bullfrog saxiphilin was the first transferrin homologue discovered that does not contain an Fe 3+ binding site. Later, a 79 kDa monomeric protein from pig plasma formed a third class of transferrins that instead of binding Fe 3+ 135 was a specific inhibitor of carbonic anhydrase.…”

Section: Saxiphilinmentioning

confidence: 99%

Saxitoxin, a toxic marine natural product that targets a multitude of receptors

2006

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Saxitoxin (STX) was discovered early last century and can contaminate seafood and drinking water, and over time has become an invaluable research tool and an internationally regulated chemical weapon. Among natural products, toxins obtain a unique reputation from their high affinity and selectivity for their target pharmacological receptor, which for STX has long been considered to only be the voltage gated sodium channel. In recent times however, STX has been discovered to also bind to calcium and potassium channels, neuronal nitric oxide synthase, STX metabolizing enzymes and two circulatory fluid proteins, namely a transferrin-like family of proteins and a unique protein found in the blood of pufferfish.

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The influence of uncoordinated histidines on iron release from transferrin. A chemical modification study.

Cited by 28 publications

References 28 publications

Kinetics of iron removal from monoferric and cobalt-labeled monoferric transferrins by diethylenetriaminepenta(methylenephosphonic acid) and diethylenetriaminepentaacetic acid

Kinetics of iron removal from monoferric and cobalt-labeled monoferric transferrins by diethylenetriaminepenta(methylenephosphonic acid) and diethylenetriaminepentaacetic acid

Calorimetric studies of the binding of ferric ions to human serum transferrin

Saxitoxin, a toxic marine natural product that targets a multitude of receptors

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