Structure of porcine pancreatic prephospholipase A2
PHOSPHOLIPASE A 2 (EC 3.1.1.4) catalyses the hydrolysis of the fatty acid ester bond at the 2-position of 1,2 diacyl sn-phosphoglycerides, and has been purified from many sources, such as mammalian pancreas 1,2 , snake venom 3 and bee venom 4 . In mammals, the enzyme is produced as a precursor, whic...
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Veröffentlicht in: | Nature (London) 1976-11, Vol.264 (5584), p.373-377 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | PHOSPHOLIPASE A
2
(EC 3.1.1.4) catalyses the hydrolysis of the fatty acid ester bond at the 2-position of 1,2 diacyl sn-phosphoglycerides, and has been purified from many sources, such as mammalian pancreas
1,2
, snake venom
3
and bee venom
4
. In mammals, the enzyme is produced as a precursor, which trypsin can convert into active phospholipase A
2
by splitting the peptide bond Arg 7–Ala 8, with the removal of the
N
-terminal heptapeptide from the molecule
5
. The activity of the different phospholipases A
2
depends on the physical state of the substrate. The enzyme from snake venom is highly active when the substrate is tightly packed in a membrane. Mammalian phospholipases cannot attack membranes; they can degrade the lecithin molecules most effectively when these are more loosely packed in micelles. All phospholipases also have some activity towards substrates in a monomeric solution. The precursors from mammalian pancreas phospholipases are also active towards the monomeric substrate molecules, but inactive to substrates in micellar form
6
. The primary structure of many of the phospholipases A
2
is known. They have a single polypeptide chain of approximately 130 amino acid residues and six or seven disulphide bridges
7–10
. There is a high degree of homology between all the enzymes. We report here the three-dimensional structure of one of these enzymes, prephospholipase A
2
from porcine pancreas. |
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ISSN: | 0028-0836 1476-4687 |
DOI: | 10.1038/264373a0 |