4pph

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== Publication Abstract from PubMed ==
== Publication Abstract from PubMed ==
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This study describes in vitro digestion of lupin seed globulins by pancreatin, trypsin and chymotrypsin. Lupin seed globulins turned out to be almost totally susceptible to chymotrypsin digestion. When panceratin or trypsin were used for digestion of lupin seed globulins, gamma-conglutin appeared to be resistant to proteolysis. Different fluorescence spectroscopic methods such as fluorescence anisotropy, fluorescence lifetimes and fluorescence quenching measurements were used for detailed characterisation of this phenomenon. A potential reason for gamma-conglutin insensitivity to digestion may be related to the fact that lysine, as well as arginine, are positively charged at cell physiological pH. Simultaneously, flavonoids at this pH are partially ionised, which may lead to the occurrence of ionic interactions between these molecules at pH 7.5. The confirmation of this explanation may be the fact that gamma-conglutin and vitexin form a static complex, which was observed using fluorescence quenching measurements.
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gamma-Conglutin from lupin seeds is an unusual 7S basic globulin protein. It is capable of reducing glycaemia in mammals, but the structural basis of this activity is not known. gamma-Conglutin shares a high level of structural homology with glycoside hydrolase inhibitor proteins, although it lacks any kind of inhibitory activity against plant cell-wall degradation enzymes. In addition, gamma-conglutin displays a less pronounced structural similarity to pepsin-like aspartic proteases, but it is proteolytically dysfunctional. Only one structural study of a legume 7S basic globulin, that isolated from soybean, has been reported to date. The quaternary assembly of soybean 7S basic globulin (Bg7S) is arranged as a cruciform-shaped tetramer comprised of two superposed dimers. Here, the crystal structure of gamma-conglutin isolated from Lupinus angustifolius seeds (LangC) is presented. The polypeptide chain of LangC is post-translationally cleaved into alpha and beta subunits but retains its covalent integrity owing to a disulfide bridge. The protomers of LangC undergo an intricate quaternary assembly, resulting in a ring-like hexamer with noncrystallographic D3 symmetry. The twofold-related dimers are similar to those in Bg7S but their assembly is different as a consequence of mutations in a beta-strand that is involved in intermolecular beta-sheet formation in gamma-conglutin. Structural elucidation of gamma-conglutin will help to explain its physiological role, especially in the evolutionary context, and will guide further research into the hypoglycaemic activity of this protein in humans, with potential consequences for novel antidiabetic therapies.
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Characterisation of different digestion susceptibility of lupin seed globulins.,Czubinski J, Dwiecki K, Siger A, Neunert G, Lampart-Szczapa E Food Chem. 2014 Jan 15;143:418-26. doi: 10.1016/j.foodchem.2013.08.015. Epub 2013, Aug 11. PMID:24054261<ref>PMID:24054261</ref>
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Structure of gamma-conglutin: insight into the quaternary structure of 7S basic globulins from legumes.,Czubinski J, Barciszewski J, Gilski M, Szpotkowski K, Debski J, Lampart-Szczapa E, Jaskolski M Acta Crystallogr D Biol Crystallogr. 2015 Feb;71(Pt 2):224-38. doi:, 10.1107/S1399004714025073. Epub 2015 Jan 23. PMID:25664733<ref>PMID:25664733</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

Revision as of 07:57, 25 February 2015

Crystal structure of conglutin gamma, a unique basic 7S globulin from lupine seeds

4pph, resolution 2.01Å

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