2gmt
From Proteopedia
(New page: 200px<br /><applet load="2gmt" size="450" color="white" frame="true" align="right" spinBox="true" caption="2gmt, resolution 1.8Å" /> '''THREE-DIMENSIONAL STR...) |
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| - | [[Image:2gmt.gif|left|200px]]<br /><applet load="2gmt" size=" | + | [[Image:2gmt.gif|left|200px]]<br /><applet load="2gmt" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2gmt, resolution 1.8Å" /> | caption="2gmt, resolution 1.8Å" /> | ||
'''THREE-DIMENSIONAL STRUCTURE OF CHYMOTRYPSIN INACTIVATED WITH (2S) N-ACETYL-L-ALANYL-L-PHENYLALANYL-CHLOROETHYL KETONE: IMPLICATIONS FOR THE MECHANISM OF INACTIVATION OF SERINE PROTEASES BY CHLOROKETONES'''<br /> | '''THREE-DIMENSIONAL STRUCTURE OF CHYMOTRYPSIN INACTIVATED WITH (2S) N-ACETYL-L-ALANYL-L-PHENYLALANYL-CHLOROETHYL KETONE: IMPLICATIONS FOR THE MECHANISM OF INACTIVATION OF SERINE PROTEASES BY CHLOROKETONES'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The reaction of enantiomerically pure | + | The reaction of enantiomerically pure (2S)-N-acetyl-L-alanyl-L-phenylalanyl alpha-chloroethane with gamma-chymotrypsin was studied as a probe of the mechanism of inactivation of serine proteases by peptidyl chloroalkanes. It was determined crystallographically that the peptidyl chloroethane alkylates His57 with retention of configuration at the chiral center, indicating a double displacement mechanism. We think it likely that a Ser195-epoxy ether adduct is an intermediate on the inactivation pathway, although other possibilities have not been disproven. Kinetic data reported by others [Angliker et al. (1988) Biochem. J. 256, 481-486] indicate that the epoxy ether intermediate is not an irreversibly inactivated form of enzyme [a conclusion confirmed experimentally (Prorok et al. (1994) Biochemistry 33, 9784-9790)] and that both ring closure of the tetrahedral intermediate to form the epoxy ether and ring opening by His57 partially limit the first-order rate constant for inactivation, ki. The peptidyl chloroethyl derivative adopts a very different active site conformation from that assumed by serine proteases inactivated by peptidyl chloromethanes. Positioning the chloroethyl derivative into the conformation adopted by chloromethyl derivatives would cause the extra methyl group to make a bad van der Waals contact with the inactivator P2 carbonyl carbon, thereby preventing the formation of the invariant hydrogen bond between the inactivator P1 amide nitrogen and the carbonyl group of Ser214. We conclude that the unusual conformation displayed by the chloroethyl derivative is caused by steric hindrance between the extra methyl group and the rest of the inactivator chain. |
==About this Structure== | ==About this Structure== | ||
| - | 2GMT is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with HIN as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Chymotrypsin Chymotrypsin], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.1 3.4.21.1] Full crystallographic information is available from [http:// | + | 2GMT is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with <scene name='pdbligand=HIN:'>HIN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Chymotrypsin Chymotrypsin], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.1 3.4.21.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2GMT OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Abeles, R.]] | [[Category: Abeles, R.]] | ||
[[Category: Kreutter, K.]] | [[Category: Kreutter, K.]] | ||
| - | [[Category: Liang, T | + | [[Category: Liang, T C.]] |
[[Category: Prorok, M.]] | [[Category: Prorok, M.]] | ||
[[Category: Ringe, D.]] | [[Category: Ringe, D.]] | ||
| - | [[Category: Steinmetz, A | + | [[Category: Steinmetz, A C.U.]] |
[[Category: HIN]] | [[Category: HIN]] | ||
[[Category: hydrolase(serine proteinase)]] | [[Category: hydrolase(serine proteinase)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:33:16 2008'' |
Revision as of 15:33, 21 February 2008
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THREE-DIMENSIONAL STRUCTURE OF CHYMOTRYPSIN INACTIVATED WITH (2S) N-ACETYL-L-ALANYL-L-PHENYLALANYL-CHLOROETHYL KETONE: IMPLICATIONS FOR THE MECHANISM OF INACTIVATION OF SERINE PROTEASES BY CHLOROKETONES
Overview
The reaction of enantiomerically pure (2S)-N-acetyl-L-alanyl-L-phenylalanyl alpha-chloroethane with gamma-chymotrypsin was studied as a probe of the mechanism of inactivation of serine proteases by peptidyl chloroalkanes. It was determined crystallographically that the peptidyl chloroethane alkylates His57 with retention of configuration at the chiral center, indicating a double displacement mechanism. We think it likely that a Ser195-epoxy ether adduct is an intermediate on the inactivation pathway, although other possibilities have not been disproven. Kinetic data reported by others [Angliker et al. (1988) Biochem. J. 256, 481-486] indicate that the epoxy ether intermediate is not an irreversibly inactivated form of enzyme [a conclusion confirmed experimentally (Prorok et al. (1994) Biochemistry 33, 9784-9790)] and that both ring closure of the tetrahedral intermediate to form the epoxy ether and ring opening by His57 partially limit the first-order rate constant for inactivation, ki. The peptidyl chloroethyl derivative adopts a very different active site conformation from that assumed by serine proteases inactivated by peptidyl chloromethanes. Positioning the chloroethyl derivative into the conformation adopted by chloromethyl derivatives would cause the extra methyl group to make a bad van der Waals contact with the inactivator P2 carbonyl carbon, thereby preventing the formation of the invariant hydrogen bond between the inactivator P1 amide nitrogen and the carbonyl group of Ser214. We conclude that the unusual conformation displayed by the chloroethyl derivative is caused by steric hindrance between the extra methyl group and the rest of the inactivator chain.
About this Structure
2GMT is a Single protein structure of sequence from Bos taurus with as ligand. Active as Chymotrypsin, with EC number 3.4.21.1 Full crystallographic information is available from OCA.
Reference
Three-dimensional structure of chymotrypsin inactivated with (2S)-N-acetyl-L-alanyl-L-phenylalanyl alpha-chloroethane: implications for the mechanism of inactivation of serine proteases by chloroketones., Kreutter K, Steinmetz AC, Liang TC, Prorok M, Abeles RH, Ringe D, Biochemistry. 1994 Nov 22;33(46):13792-800. PMID:7947790
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