東華大學圖書館 |

Language: English

Help

回圖書館首頁

手機版館藏查詢

Back

Switch To: Labeled | MARC Mode | ISBD

Selective open-channel block of KV1 ...

Brock, Mathew William.

Linked to FindBook

Google Book

Amazon

博客來

Selective open-channel block of KV1 potassium channels by S-nitrosodithiothreitol (SNDTT).

Record Type:	Electronic resources : Monograph/item
Title/Author:	Selective open-channel block of KV1 potassium channels by S-nitrosodithiothreitol (SNDTT)./
Author:	Brock, Mathew William.
Description:	214 p.
Notes:	Source: Dissertation Abstracts International, Volume: 64-03, Section: B, page: 1109.
Contained By:	Dissertation Abstracts International64-03B.
Subject:	Biology, Neuroscience. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3085165

Selective open-channel block of KV1 potassium channels by S-nitrosodithiothreitol (SNDTT).
Brock, Mathew William.

Selective open-channel block of KV1 potassium channels by S-nitrosodithiothreitol (SNDTT). - 214 p.

Source: Dissertation Abstracts International, Volume: 64-03, Section: B, page: 1109.

Thesis (Ph.D.)--Stanford University, 2003.

Blockade of voltage-gated K+ (Kv) channels is a feature of many large quaternary and tertiary amines. These compounds bind with a 1:1 stoichiometry in an aqueous cavity along the channel pore that is exposed to the cytoplasm only when channels are open. This thesis addresses the action of S-nitrosodithiothreitol (SNDTT; ONSCH2CH(OH)CH(OH)CH2SNO), which produces qualitatively similar "open-channel block" in Kv channels despite its unconventional (small, electrically neutral, and polar) structure. In whole-cell voltage-clamped squid giant fiber lobe neurons, bath-applied SNDTT causes reversible time-dependent block of delayed-rectifier K + channels, but not Na+ or Ca2+ channels. The inactivation-removed ShakerB (ShBDelta) Kv1 channel expressed in HEK 293 cells is blocked in a similar manner and was used to further characterize the action of SNDTT. Dose-response data for ShBDelta indicate that two molecules of SNDTT can bind to each open channel, but binding of a single molecule is sufficient for block. The dissociation constant for the second molecule bound (0.14 mM) is lower than for the first (0.67 mM), indicating cooperativity. Surprisingly, the steady-state level of block by this electrically neutral compound has a voltage-dependence (&sim;-0.25 e0) similar in magnitude but opposite in directionality to that reported for amines. Both nitrosyl (-NO) groups on SNDTT (one on each sulfur atom) are required for block, but transfer of these reactive groups to channel cysteine residues is not involved. Competition with internal tetraethylammonium indicates that bath-applied SNDTT crosses the cell membrane to act at an internal site. Through targeted mutagenesis, we have identified two contiguous residues (Thr469 and Ile470) in the channel cavity that are strong determinants of SNDTT sensitivity. At position 469, a side chain -OH group is required for high affinity block, and may form a hydrogen bond with an -NO group on SNDTT. Finally, SNDTT is remarkably selective for Kv1 subfamily channels. When individually expressed in HEK 293 cells, rat Kv1.1--1.6 display profound time-dependent block by SNDTT, an effect not seen for rat Kv2.1, 3.1, or 4.2. SNDTT may therefore be useful as a pharmacological probe of Kv subtype, and may represent the prototype for a new class of pharmaceuticals selectively targeting Kv1 channels.Subjects--Topical Terms:

1017680
Biology, Neuroscience.

Selective open-channel block of KV1 potassium channels by S-nitrosodithiothreitol (SNDTT).
LDR:03245nmm 2200277 4500 001 1860493
005 20041028080310.5
008 130614s2003 eng d
035 $a (UnM)AAI3085165
035 $a AAI3085165
040 $a UnM $c UnM
100 1 $a Brock, Mathew William. $3 1948127
245 1 0 $a Selective open-channel block of KV1 potassium channels by S-nitrosodithiothreitol (SNDTT).
300 $a 214 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-03, Section: B, page: 1109.
500 $a Adviser: William F. Gilly.
502 $a Thesis (Ph.D.)--Stanford University, 2003.
520 $a Blockade of voltage-gated K+ (Kv) channels is a feature of many large quaternary and tertiary amines. These compounds bind with a 1:1 stoichiometry in an aqueous cavity along the channel pore that is exposed to the cytoplasm only when channels are open. This thesis addresses the action of S-nitrosodithiothreitol (SNDTT; ONSCH2CH(OH)CH(OH)CH2SNO), which produces qualitatively similar "open-channel block" in Kv channels despite its unconventional (small, electrically neutral, and polar) structure. In whole-cell voltage-clamped squid giant fiber lobe neurons, bath-applied SNDTT causes reversible time-dependent block of delayed-rectifier K + channels, but not Na+ or Ca2+ channels. The inactivation-removed ShakerB (ShBDelta) Kv1 channel expressed in HEK 293 cells is blocked in a similar manner and was used to further characterize the action of SNDTT. Dose-response data for ShBDelta indicate that two molecules of SNDTT can bind to each open channel, but binding of a single molecule is sufficient for block. The dissociation constant for the second molecule bound (0.14 mM) is lower than for the first (0.67 mM), indicating cooperativity. Surprisingly, the steady-state level of block by this electrically neutral compound has a voltage-dependence (&sim;-0.25 e0) similar in magnitude but opposite in directionality to that reported for amines. Both nitrosyl (-NO) groups on SNDTT (one on each sulfur atom) are required for block, but transfer of these reactive groups to channel cysteine residues is not involved. Competition with internal tetraethylammonium indicates that bath-applied SNDTT crosses the cell membrane to act at an internal site. Through targeted mutagenesis, we have identified two contiguous residues (Thr469 and Ile470) in the channel cavity that are strong determinants of SNDTT sensitivity. At position 469, a side chain -OH group is required for high affinity block, and may form a hydrogen bond with an -NO group on SNDTT. Finally, SNDTT is remarkably selective for Kv1 subfamily channels. When individually expressed in HEK 293 cells, rat Kv1.1--1.6 display profound time-dependent block by SNDTT, an effect not seen for rat Kv2.1, 3.1, or 4.2. SNDTT may therefore be useful as a pharmacological probe of Kv subtype, and may represent the prototype for a new class of pharmaceuticals selectively targeting Kv1 channels.
590 $a School code: 0212.
650 4 $a Biology, Neuroscience. $3 1017680
650 4 $a Biophysics, General. $3 1019105
650 4 $a Chemistry, Organic. $3 516206
690 $a 0317
690 $a 0786
690 $a 0490
710 2 0 $a Stanford University. $3 754827
773 0 $t Dissertation Abstracts International $g 64-03B.
790 1 0 $a Gilly, William F., $e advisor
790 $a 0212
791 $a Ph.D.
792 $a 2003
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3085165