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== 1CPX - Carboxypeptidase A from Bovine Pancreas == | |||
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== | ==Introduction== | ||
<scene name='69/694222/3cpaoverview/1'>Carboxypeptidase A (peptidyl-L-amino acid hydrolase, EC 3.4.17.1, often abbreviated CPA)</scene> is a metallo[http://en.wikipedia.org/wiki/exopeptidase exopeptidase] that hydrolytically cleaves peptides at the [http://en.wikipedia.org/wiki/C-terminus C-terminal] peptide bond containing hydrophobic side chains. <ref name="CPA1">Bukrinsky JT, Bjerrum MJ, Kadziola A. 1998. Native carboxypeptidase A in a new crystal environment reveals a different conformation of the important tyrosine 248. ''Biochemistry''. 37(47):16555-16564. [http://pubs.acs.org/doi/abs/10.1021/bi981678i DOI: 10.1021/bi981678i]</ref> Specifically, CPA is a Zn<sup>2+</sup> [http://en.wikipedia.org/wiki/Metalloprotein#Metalloenzymes metalloenzyme] that carries out the hydrolysis of C-terminal polypeptide residues through the [http://en.wikipedia.org/wiki/Deprotonation deprotonation] of a water molecule that is coordinated to the Zn<sup>2+</sup> ion in the enzyme's [http://en.wikipedia.org/wiki/Active_site active site].<ref name="CPA2">Christianson DW, Lipscomb WN. 1989. Carboxypeptidase A. ''Acc. Chem. Res.'' 22:62-69.</ref> From bovine pancreas, 1CPX has been crystallized in a new environment alongside two Zn<sup>2+</sup> ions, one catalytic, the other inhibitory. The inhibitory Zn<sup>2+</sup> ion in this more recent crystal structure not only prevents 1CPX from undergoing its [http://en.wikipedia.org/wiki/hydrolysis hydrolysis] mechanism; but also, this crystallographic data reveals a different conformation of the Tyr248 (GREEN LINK) residue suggesting alternative mechanistic behavior. <ref name="CPA1">Bukrinsky JT, Bjerrum MJ, Kadziola A. 1998. Native carboxypeptidase A in a new crystal environment reveals a different conformation of the important tyrosine 248. ''Biochemistry''. 37(47):16555-16564. [http://pubs.acs.org/doi/abs/10.1021/bi981678i DOI: 10.1021/bi981678i]</ref> 1CPX consists of a single polypeptide chain that contains 307 amino acids. CPA proteins must first be activated by either [http://en.wikipedia.org/wiki/Trypsin trypsin] or [http://en.wikipedia.org/wiki/Chymotrypsin chymotrypsin] in order to achieve an active form that serves its biological function.<ref name="CPA1" /> This crystallographic data presents 1CPX activated by trypsin in its β-form and orthorhombic crystal form. | |||
This is about 1CPX. This is a carboxypeptidase from bovine pancreas with two Zinc binding sites.This is about 1CPX. This is a carboxypeptidase from bovine pancreas with two Zinc binding sites.This is about 1CPX. This is a carboxypeptidase from bovine pancreas with two Zinc binding sites.This is about 1CPX. This is a carboxypeptidase from bovine pancreas with two Zinc binding sites.This is about 1CPX. | |||
<scene name='75/752350/Tyr_248_zoom/1'>active site</scene> | |||
This is a carboxypeptidase from bovine pancreas with two Zinc binding sites. | |||
This is a | <Structure load='1CPX' size='350' frame='true' align='left' caption='This is a caption about 1CPX' scene='75/752350/Tyr_248_zoom/1' /> | ||
[[Image:1CPX Cartoon.png|200 px|right|thumb|Figure Legend]] | |||