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1hny

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[[Image:1hny.jpg|left|200px]]
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==Overview==
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{{ABSTRACT_8528071}}
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The structure of human pancreatic alpha-amylase has been determined to 1.8 A resolution using X-ray diffraction techniques. This enzyme is found to be composed of three structural domains. The largest is Domain A (residues 1-99, 169-404), which forms a central eight-stranded parallel beta-barrel, to one end of which are located the active site residues Asp 197, Glu 233, and Asp 300. Also found in this vicinity is a bound chloride ion that forms ligand interactions to Arg 195, Asn 298, and Arg 337. Domain B is the smallest (residues 100-168) and serves to form a calcium binding site against the wall of the beta-barrel of Domain A. Protein groups making ligand interactions to this calcium include Asn 100, Arg 158, Asp 167, and His 201. Domain C (residues 405-496) is made up of anti-parallel beta-structure and is only loosely associated with Domains A and B. It is notable that the N-terminal glutamine residue of human pancreatic alpha-amylase undergoes a posttranslational modification to form a stable pyrrolidone derivative that may provide protection against other digestive enzymes. Structure-based comparisons of human pancreatic alpha-amylase with functionally related enzymes serve to emphasize three points. Firstly, despite this approach facilitating primary sequence alignments with respect to the numerous insertions and deletions present, overall there is only approximately 15% sequence homology between the mammalian and fungal alpha-amylases. Secondly, in contrast, these same studies indicate that significant structural homology is present and of the order of approximately 70%. Thirdly, the positioning of Domain C can vary considerably between alpha-amylases. In terms of the more closely related porcine enzyme, there are four regions of polypeptide chain (residues 237-250, 304-310, 346-354, and 458-461) with significantly different conformations from those in human pancreatic alpha-amylase. At least two of these could play a role in observed differential substrate and cleavage pattern specificities between these enzymes. Similarly, amino acid differences between human pancreatic and salivary alpha-amylases have been localized and a number of these occur in the vicinity of the active site.
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==About this Structure==
==About this Structure==
1HNY is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. The following page contains interesting information on the relation of 1HNY with [[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb74_1.html Alpha-amylase]]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1HNY OCA].
1HNY is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. The following page contains interesting information on the relation of 1HNY with [[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb74_1.html Alpha-amylase]]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1HNY OCA].
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==Reference==
 
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The structure of human pancreatic alpha-amylase at 1.8 A resolution and comparisons with related enzymes., Brayer GD, Luo Y, Withers SG, Protein Sci. 1995 Sep;4(9):1730-42. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/8528071 8528071]
 
[[Category: Alpha-amylase]]
[[Category: Alpha-amylase]]
[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
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[[Category: Brayer, G D.]]
[[Category: Brayer, G D.]]
[[Category: Luo, Y.]]
[[Category: Luo, Y.]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 19:03:18 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Jun 26 17:29:27 2008''

Revision as of 14:29, 26 June 2008

Image:1hny.png

Template:STRUCTURE 1hny

THE STRUCTURE OF HUMAN PANCREATIC ALPHA-AMYLASE AT 1.8 ANGSTROMS RESOLUTION AND COMPARISONS WITH RELATED ENZYMES


Template:ABSTRACT 8528071

About this Structure

1HNY is a Single protein structure of sequence from Homo sapiens. The following page contains interesting information on the relation of 1HNY with [Alpha-amylase]. Full crystallographic information is available from OCA.

Page seeded by OCA on Thu Jun 26 17:29:27 2008

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