Measurement of the binding of colipase to a triacylglycerol substrate
(1980) In Biochimica et Biophysica Acta 617(3). p.82-371- Abstract
The binding between colipase and two triacylglycerol substrates, tributyrin and Intralipid, in the presence of bile salts have been determined quantitatively by a method based on equilibrium partition in an aqueous two-phase system. In the model proposed the triacylglycerol, in the form of spherical droplets covered with bile salt, is assumed to have a certain number of independent binding sites at the surface for colipase. The binding of colipase to tributyrin at pH 7.0 in the presence of 4 mM sodium taurodeoxycholate and 150 mM NaCl had a dissociation constant Kd = 3.3 . 10(-7) M; the concentration of binding sites was 1.2 . 10(-6) M in a 102 mM tributyrin emulsion. When tributyrin was dispersed in 1 mM and 12 mM sodium... (More)
The binding between colipase and two triacylglycerol substrates, tributyrin and Intralipid, in the presence of bile salts have been determined quantitatively by a method based on equilibrium partition in an aqueous two-phase system. In the model proposed the triacylglycerol, in the form of spherical droplets covered with bile salt, is assumed to have a certain number of independent binding sites at the surface for colipase. The binding of colipase to tributyrin at pH 7.0 in the presence of 4 mM sodium taurodeoxycholate and 150 mM NaCl had a dissociation constant Kd = 3.3 . 10(-7) M; the concentration of binding sites was 1.2 . 10(-6) M in a 102 mM tributyrin emulsion. When tributyrin was dispersed in 1 mM and 12 mM sodium taurodeoxycholate the dissociation constant was somewhat higher, 6.3 . 10(-7) M and 6.0 . 10(-7) M, respectively. Thus the binding strength was optimal at 4 mM sodium taurodeoxycholate. At the same time the concentration of binding sites decreased from 4.1 . 10(-6) M for 1 mM sodium taurodeoxycholate to 1.4 . 10(-6) M for 12 mM sodium taurodeoxycholate. This indicated that at higher bile salt concentration the bile salt acted as non-competitive inhibitors on the binding of colipase to the substrate, thus binding to other sites than colipase to the substrate. The binding of colipase to Intralipid, an emulsion of a long-chain triacylglycerol stabilized with phosphatidylcholine and glycerol, was more complex with indications of several different binding sites with different affinity. The majority of these had a dissociation constant Kd = 1.2 . 10(-6) M in the presence of 4 mM sodium taurodeoxycholate and 150 mM. With each droplet having a diameter of 10(-4) cm, the number of binding sites on each droplet was determined to 1.96 . 10(5) and the average area available for each colipase molecule to 1600 A at saturation. Colipase on denaturation has a surface of 1320 A.
(Less)
- author
- Erlanson-Albertsson, C LU
- organization
- publishing date
- 1980-03-21
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Animals, Binding Sites, Colipases/metabolism, Fat Emulsions, Intravenous/metabolism, Kinetics, Models, Biological, Proteins/metabolism, Swine, Taurodeoxycholic Acid/pharmacology, Triglycerides/metabolism
- in
- Biochimica et Biophysica Acta
- volume
- 617
- issue
- 3
- pages
- 82 - 371
- publisher
- Elsevier
- external identifiers
-
- scopus:0019330119
- pmid:7370284
- ISSN
- 0006-3002
- DOI
- 10.1016/0005-2760(80)90003-X
- language
- English
- LU publication?
- yes
- id
- 64d34237-8609-41d7-82e4-8acf49509d57
- date added to LUP
- 2019-01-31 13:54:13
- date last changed
- 2024-01-15 13:26:49
@article{64d34237-8609-41d7-82e4-8acf49509d57,
abstract = {{<p>The binding between colipase and two triacylglycerol substrates, tributyrin and Intralipid, in the presence of bile salts have been determined quantitatively by a method based on equilibrium partition in an aqueous two-phase system. In the model proposed the triacylglycerol, in the form of spherical droplets covered with bile salt, is assumed to have a certain number of independent binding sites at the surface for colipase. The binding of colipase to tributyrin at pH 7.0 in the presence of 4 mM sodium taurodeoxycholate and 150 mM NaCl had a dissociation constant Kd = 3.3 . 10(-7) M; the concentration of binding sites was 1.2 . 10(-6) M in a 102 mM tributyrin emulsion. When tributyrin was dispersed in 1 mM and 12 mM sodium taurodeoxycholate the dissociation constant was somewhat higher, 6.3 . 10(-7) M and 6.0 . 10(-7) M, respectively. Thus the binding strength was optimal at 4 mM sodium taurodeoxycholate. At the same time the concentration of binding sites decreased from 4.1 . 10(-6) M for 1 mM sodium taurodeoxycholate to 1.4 . 10(-6) M for 12 mM sodium taurodeoxycholate. This indicated that at higher bile salt concentration the bile salt acted as non-competitive inhibitors on the binding of colipase to the substrate, thus binding to other sites than colipase to the substrate. The binding of colipase to Intralipid, an emulsion of a long-chain triacylglycerol stabilized with phosphatidylcholine and glycerol, was more complex with indications of several different binding sites with different affinity. The majority of these had a dissociation constant Kd = 1.2 . 10(-6) M in the presence of 4 mM sodium taurodeoxycholate and 150 mM. With each droplet having a diameter of 10(-4) cm, the number of binding sites on each droplet was determined to 1.96 . 10(5) and the average area available for each colipase molecule to 1600 A at saturation. Colipase on denaturation has a surface of 1320 A.</p>}},
author = {{Erlanson-Albertsson, C}},
issn = {{0006-3002}},
keywords = {{Animals; Binding Sites; Colipases/metabolism; Fat Emulsions, Intravenous/metabolism; Kinetics; Models, Biological; Proteins/metabolism; Swine; Taurodeoxycholic Acid/pharmacology; Triglycerides/metabolism}},
language = {{eng}},
month = {{03}},
number = {{3}},
pages = {{82--371}},
publisher = {{Elsevier}},
series = {{Biochimica et Biophysica Acta}},
title = {{Measurement of the binding of colipase to a triacylglycerol substrate}},
url = {{http://dx.doi.org/10.1016/0005-2760(80)90003-X}},
doi = {{10.1016/0005-2760(80)90003-X}},
volume = {{617}},
year = {{1980}},
}