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Membrane Binding and Transport of Polylysine : = Heparin Complexes in Cultured Chinese Hamster Ovary Cells.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Membrane Binding and Transport of Polylysine :/
Reminder of title:	Heparin Complexes in Cultured Chinese Hamster Ovary Cells.
Author:	Morad, Nader A.
Description:	1 online resource (109 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 46-07, Section: B.
Contained By:	Dissertations Abstracts International46-07B.
Subject:	Pathology. -
Online resource:	click for full text (PQDT)
ISBN:	9798204938007

Membrane Binding and Transport of Polylysine : = Heparin Complexes in Cultured Chinese Hamster Ovary Cells.
Morad, Nader A.

Membrane Binding and Transport of Polylysine :Heparin Complexes in Cultured Chinese Hamster Ovary Cells. - 1 online resource (109 pages)

Source: Dissertations Abstracts International, Volume: 46-07, Section: B.

Thesis (Ph.D.)--Boston University, 1985.

Includes bibliographical references

We investigated surface binding and endocytosis of ('14)C-poly(Lys):heparin complex in cultured Chinese Hamster Ovary (CHO) cells. This complex is of interest as a potential carrier for intracellular drug delivery. As determined by gel chromatography and acridine orange titration in heparin excess, the stoichiometric weight ratio of poly(Lys) to heparin is 1.0 to 1.25. Its surface binding and cellular uptake by monolayers of CHO cells show saturation kinetics, with a Kd of about 2 x 10('-7) M for binding and 5 x 10('6) binding sites per cell. These sites will bind complexes formed between heparin and homopolymers of other cationic amino acids, but do not interact with complexes in which poly(Lys) is replaced by protamine sulfate, lysine-rich histones, and poly(Lys) copolymers, or with complexes in which heparin is replaced by chondroitin sulfates A, B, and C, poly(glutamic) acid or reduced heparin (carboxyl groups reduced to methyl hydroxyl groups). The kinetics of surface binding and cellular uptake of poly(Lys):heparin complex differ markedly from those of poly(Lys) and heparin. Even though heparin binding is saturable, its uptake is essentially non-saturable and consistent with fluid-phase endocytosis. By contrast the complex appears to be transported by receptor-mediated endocytosis. Only negligible amounts of heparin bound to the cell surface at 0(DEGREES)C are internalized during a 2 h reincubation at 37(DEGREES)C, while under comparable conditions about 40% of surface-bound complex is endocytosed. That the complexed and uncomplexed heparin bind to different sites is also indicated by the fact that their interaction with cells is influenced differently by cell detachment with trypsin, detachment with EGTA, or exposure to acid pH. The effect of acid pH is of particular interest. At pH 4.5, the transport of the complex is markedly increased, while the uptake of other macromolecules is markedly decreased and the cellular permeability to trypan blue is unchanged. The question arises whether a similar translocation could occur through the membranes of acidic endosomes.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798204938007Subjects--Topical Terms:

668553
Pathology.
Index Terms--Genre/Form:

554714
Electronic books.

Membrane Binding and Transport of Polylysine : = Heparin Complexes in Cultured Chinese Hamster Ovary Cells.
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100 1 $a Morad, Nader A. $3 1466596
245 1 0 $a Membrane Binding and Transport of Polylysine : $b Heparin Complexes in Cultured Chinese Hamster Ovary Cells.
264 0 $c 1985
300 $a 1 online resource (109 pages)
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500 $a Source: Dissertations Abstracts International, Volume: 46-07, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
502 $a Thesis (Ph.D.)--Boston University, 1985.
504 $a Includes bibliographical references
520 $a We investigated surface binding and endocytosis of ('14)C-poly(Lys):heparin complex in cultured Chinese Hamster Ovary (CHO) cells. This complex is of interest as a potential carrier for intracellular drug delivery. As determined by gel chromatography and acridine orange titration in heparin excess, the stoichiometric weight ratio of poly(Lys) to heparin is 1.0 to 1.25. Its surface binding and cellular uptake by monolayers of CHO cells show saturation kinetics, with a Kd of about 2 x 10('-7) M for binding and 5 x 10('6) binding sites per cell. These sites will bind complexes formed between heparin and homopolymers of other cationic amino acids, but do not interact with complexes in which poly(Lys) is replaced by protamine sulfate, lysine-rich histones, and poly(Lys) copolymers, or with complexes in which heparin is replaced by chondroitin sulfates A, B, and C, poly(glutamic) acid or reduced heparin (carboxyl groups reduced to methyl hydroxyl groups). The kinetics of surface binding and cellular uptake of poly(Lys):heparin complex differ markedly from those of poly(Lys) and heparin. Even though heparin binding is saturable, its uptake is essentially non-saturable and consistent with fluid-phase endocytosis. By contrast the complex appears to be transported by receptor-mediated endocytosis. Only negligible amounts of heparin bound to the cell surface at 0(DEGREES)C are internalized during a 2 h reincubation at 37(DEGREES)C, while under comparable conditions about 40% of surface-bound complex is endocytosed. That the complexed and uncomplexed heparin bind to different sites is also indicated by the fact that their interaction with cells is influenced differently by cell detachment with trypsin, detachment with EGTA, or exposure to acid pH. The effect of acid pH is of particular interest. At pH 4.5, the transport of the complex is markedly increased, while the uptake of other macromolecules is markedly decreased and the cellular permeability to trypan blue is unchanged. The question arises whether a similar translocation could occur through the membranes of acidic endosomes.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2024
538 $a Mode of access: World Wide Web
650 4 $a Pathology. $3 668553
655 7 $a Electronic books. $2 local $3 554714
690 $a 0571
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a Boston University. $3 845551
773 0 $t Dissertations Abstracts International $g 46-07B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=8524187 $z click for full text (PQDT)