Human Anatomy, Physiology, and Medicine. Anything human!
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i'm doing a project on endorphins and have had a lot of trouble finding specific information on the levels of molecular structure (primary, secondary etc..) even when i've narrowed down my searches to specific alpha-,beta-,gamma- queries, i've been unable to find anything. can anyone help me out? thanks a lot!
I don’t quite know what you’re asking. The endorphins or enkephalins are small peptides. I wouldn’t expect much secondary or tertiary structure to be present. The one crystal structure that I’ve seen is an extended peptide with no additional secondary or tertiary structure There may be other enkephalin structures with different things to say about them; check http://www.rcsb.org/pdb/home/home.do if you want to know what structures are available. There once was the thought that an amphipathic helix was required for a particular endorphin to be active, but I haven’t heard anything about it for years. If you are referring to things like alpha- or beta-endorphin, that has little to do with the structure of the endorphins. These were names given to distinguish the types of endorphins and may reflect nothing more than elution order out of a column or tissue source. You'd probably have to go way back to an old review of the literature to get an explanation of the names, but don't expect there to be much about structure beyond sequence, anyway.
Just in case anyone is still following this!
Simplify your google search: <endorphin structure>
In 1981 Pierre Nicholas, et. al. published a couple of papers on tertiary structure of camel beta-endorphin (CBE). They reported changes in the UV spectra of intact versus digested CBE (this is called difference spectroscopy). This suggests the molecule in solution has a stable three-dimensional conformation, because its UV spectrum differs from that of the free amino acids. By comparing the difference spectra with time-release of peptides, they conclude the N-terminal tyrosyl residue interacts with the C-terminus, and that this interaction disappears when the bond between Ala-21 and Ile-22 is cleaved. See the complete article at http://www.pubmedcentral.nih.gov/picren ... obtype=pdf.
I do not find a PBD listing for any endorphin at Protein Data Bank. Nothing for opioid receptor, either. Obviously the functional tertiary structure of an endorphin is in the ligand-receptor complex.
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